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FRCS Part 2 > Skull base > Flashcards

Skull base Flashcards

1
Q

When was the House-Brackmann grading described?

A

1985

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2
Q

What is the House-Brackmann grading?

A

1 - normal (score 8/8) 2 - mild dysfunction with slight weakness. Normal symmetry and tone (score 7/8). 3 - moderate dysfunction. Obvious but not disfiguring difference between the two sides. Noticeable synkineses. Complete eye closure with effort. (score 5-6/8) 4 - moderately severe dysfunction. Obvious weakness with disfiguring asymmetric. Incomplete eye closure. (score 3-4/8) 5 - severe dysfunction. Barely perceptible motion. Slight movement of the mouth. (score 1-2/8) 6 - total paralysis. (score 0/8)

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3
Q

How did the original House & Brackmann (1985) paper propose standardisation of the grading scale?

A

Measuring the movement of angle of mouth and the eyebrow and comparing to the unaffected side. The difference is based on 2.5 mm gradations. The maximum score is 8 (4 for the mouth and 4 for the eyebrow),

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4
Q

How does the vestibular nerve appear during surgery?

A

More gray than the cochlear and facial nerves due to less myelination

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5
Q

Where is the endolymphatic sac?

A

Midway between the posterior edge of the IAM and the sigmoid sinus

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6
Q

What are the differences between an UMN and LMN facial nerve palsy?

A

In UMN cases the forehead is preserved as this is bilaterally represented and emotional facial expression may be maintained e.g. smiling at a joke

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7
Q

What is Gubler-Millard syndrome?

A

Base of pons lesion causing CN7, CN6 and contralateral hemiplegia

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8
Q

What is benedikt syndrome?

A

CN3 palsy with red nucleus involvement (coarse intention tremor) and contralateral hemiparesis. Dorsal midbrain lesion.

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9
Q

What forms the facial colliculus?

A

Facial fibres passing around the abducens nucleus

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10
Q

What is crocodile tear syndrome?

A

Lesions of the facial nerve cause abberent connections in the pterygopalatine ganglion between mastication and lacrimation. Chewing therefore results in lacrimation when eating.

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11
Q

What are the segments of the facial nerve?

A

Brainstem

Cisternal

Meatal

Labyrinthine - geniculate ganglion gives off GSPN (dry eye)

Tympanic - nerve to stapedius (hyperacusis)

Mastoid - chorda tympani (loss of taste)

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12
Q

What pathway control lacrimation (tearing)?

A

Superior salivary nucleus

Nervus intermedius

GSPN > Vidian

Sphenopalatine ganglion

Zygomatic and lacrimal nerves

Lacrimal gland

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13
Q

Which nerve do fibres to the submandibular and sublingual glands run on?

A

Chorda Tympani

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14
Q

What is the most likely underlying cause for Bell’s palsy?

A

Viral / Inflammatory / Demyelinating polyneuritis

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15
Q

What features may be associated with Bell’s palsy?

A

Follows a distal to proximal pattern with motor loss first then

Facial and retroauricular pain (60%)

Dysgeusia (=altered taste) (60%) = chorda tympani

Hyperacusis (30%) = n to stapedius

Reduced tearing (17%) = GSPN

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16
Q

What is the evidence for treatments of Bell’s palsy?

A

In patients with Bell’s palsy, early treatment with prednisolone significantly improves the chances of complete recovery at 3 and 9 months. There is no evidence of a benefit of acyclovir given alone or an additional benefit of acyclovir in combination with prednisolone. NEJM RCT 2007 Sullivan et al.

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17
Q

What are the surgical treatment options for facial nerve injury?

A
  1. Approximation if there is a transection via direct anastomosis or cable graft with sural nerve
  2. Extracranial anastomosis (CN9/11/12
  3. Facial suspension
  4. Tarsorrhaphy
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18
Q

What are the two types of hearing loss?

A

Conductive and sensorineural - distinguished using Rinne and Weber’s test

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19
Q

What are the Rinne and Weber’s test findings in a normal patient?

A

Weber is central i.e. does not lateralize to one side

Rinne has AC>BC

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20
Q

What is a positive Rinne’s test?

A

When AC>BC which is normal. If BC>AC this is a negative finding and suggests conductive hearing loss in that ear.

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21
Q

How do you perform Rinne’s test?

A

512 Hz tuning fork on the mastoid bone.

When no longer heard it should be moved to the ear.

If it can then be heard again it is positive.

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22
Q

How do you interpret Weber’s tests?

A

A tuning fork in the center of the head does not lateralise if the hearing is normal. It lateralises to the side where there is a conductive hearing loss of the contralateral side if there is a sensorineural hearing loss.

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23
Q

Interpret the following:

Webers lateralises to the right

Right Rinne’s is negative (BC>AC)

Left Rinne’s is positive (AC>BC)

A

Right conductive hearing loss

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24
Q

Interpret the following:

Webers lateralises to the right

Right Rinne’s is positive (AC>BC)

Left Rinne’s is positive (AC>BC)

A

Left sensorineural hearing loss

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25
Q

What is Hitzelberger’s sign?

A

Compression of nervus intermedius by a vestibular schwannoma causing numbness over the posterior aspect of the EAC

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26
Q

Which nerves supply the external ear?

A

Pinna = Greater auricular C2/3

Back of ear = Lesser occipital C2

Anterior and superior ear = Auriculotemporal V3

Posterior inferior EAC and = Auricular branch of vagus (Arnold’s nerve)

Posterior inferior EAC = Facial nerve sensory branch via nervus intermedius

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27
Q

What causes sensorineural hearing loss?

A

Sensory - cochlear damage from noise exposure, drugs (gentamicin) and viral labyrinthitis.

Neural - Compression of CN8 in the CP angle

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28
Q

What is the mechanism behind caloric testing?

A

The cold water causes the endolymph to become dense and fall.

This pulls the ipsilateral cupula away from the utricle, reducing the firing and causes nystagmus with the fast component to the contralateral side.

Movement of the cupla towards to the utricle = ampulopetal; Away = ampulofugal.

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29
Q

Describe the vestibular pathway

A

Cupula in each of the semicircular canals > CN8 > Vestibular nucleus int he medulla > CN6 and 3 bilaterally via the MLF and control medial and lateral rectus coordination.

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30
Q

How do you interpret tympanometry?

A

X axis is the static pressure and Y axis is the volume.

A = Normal

B = flattened curve suggestive of an compressible fluid in the middle ear

C = Negative compliance suggesting a negative pressure in the middle ear which occurs with eustachian tube dysfunction

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31
Q

What tests help to distinguish conductive and sensorineural hearing loss?

A

PTA / tymps

Otoacoustic emissions

BSAER

Stapedial reflex out of proportion to PTA suggests neural lesion

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32
Q

What is the most reliable indicator of an acoustic neuroma from the BAER?

A

Increased intraaural latency in wave V. BAER sensitivity is 90%.

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33
Q

Names the structures

A
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34
Q

What is the different ionic composition of endolymph and perilymph?

A

Endolymph has high K+ like intracellular fluid, Perilymph has a higher Na+ like extracellular fluid and CSF

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35
Q

How do you use Rinne’s and Weber’s test to localise hearing loss?

A
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36
Q

What is the modiolus?

A

The conical central axis of the cochlea

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37
Q

What are the PTA findings with noise-injury hearing loss?

A

Sensorineural hearing loss at 4kHz

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38
Q

What genetic condition causes haematuria and high frequency hearing loss?

A

Alport syndrome

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39
Q

Which nerve do vestibular schwannomas arise from?

A

Superior division of the vestibular nerve (not the cochlear nerve!) from the Obersteiner-Redlich (where oligodendrocytes are replaced by schwann cells) zone ~1cm from where the nerve exits the brainstem.

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40
Q

What is the function of schwannomin / merlin?

A

A tumour suppressor gene involved with cytoskeleton:membrane binding

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41
Q

What proportion of VS are unilateral?

A

95%

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42
Q

Which patients should undergo genetic screening for NF2?

A

Unilateral VS and <40 years

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43
Q

What is the difference between VS from sporadic cases compared to NF2?

A

Sporadic cases displace the CN8 whilst in NF2 they form grape-like clusters that infiltrate the nerve.

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44
Q

What are the histological subtypes of vestibular schwannomas?

A

Antoni A (narrow elongated bipolar cells) and Antoni B (loose reticulated). Verocay bodies (eosinophilic areas surrounded by spindle shaped schwann cells) are also seen.

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45
Q

What is the presenting triad of VS?

A

Ipsilateral sensorineural hearing loss, Tinnitus and Vertigo.

Large tumours go on to cause brainstem compression (facial numbness > weakness > diplopia) / hydrocephalus.

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46
Q

What is the cause of hearing loss with VS?

A

Initially thought to be stretch on the CN8, but new evidence suggests secretion of toxic factors causing cochlear damage

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47
Q

What is the hearing loss pattern with VS?

A

Gradual and insidious. 70% have high-frequency loss causing high pitch tinnitus and word discrimination is affected more.

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48
Q

What are the causes sensorineural hearing loss

A

Tumour, infection, toxin, vascular and autoimmune

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49
Q

Why does CN5 palsy occur before CN7 with VS?

A

As sensory fibres are more vulnerable to compression than motor fibres

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50
Q

What is the earliest clinical finding with VS?

A

SNL hearing loss

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51
Q

What are the examination findings in patients with VS?

A

SNL hearing loss (66%) Loss of corneal reflex (33%) Nystagmus (26%) Facial numbness (26%) Facial weakness (12%) Diplopia (11%) Papilloedema (10%) Babinski sign (5%)

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52
Q

Explain the Rinne’s and Weber’s test with VS?

A

Weber - tuning fork at vertek > localises to the contralateral side Rinne’s - positive i.e. air>bone conduction on both sides

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53
Q

What is the House-Brackmann grading system (1985)?

A

1 = normal 2 = mild dysfunction with normal symmetry at rest but slight weakness 3 = moderated dysfunction with non-dyfiguring asymmetry. Complete eye closure with effort. 4 = Moderate to severe dysfunction = dysfiguring asymmetry with incomplete eye closure 5 = Barely perceptible motion 6 = No movement

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54
Q

What is the differential diagnosis of a CP angle lesion?

A

VS Meningioma Schwannoma of an adjacent cranial nerve e.g. CN5 or 7 Arachnoid cyst Epidermoid Metastasis Aneurysm Neurenteric cyst

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55
Q

How would you investigate a patient with a CP angle lesion?

A

MRI +/- contrast with CISS/FIESTA

CT skull base

Audiometry (PTA / Tymps / speech discrimination)

Further ancillary testing if small VS (<1.5 cm dia) include ENG / VEMP / ABR.

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56
Q

Why should you order a thin CT for pre-op VS planning?

A

Middle fossa - geniculate ganglion position and identify dehsicence

Translab - pneumatisation of the mastoid and position of the sigmoid sinus and jugular bulb (high riding)

Retrosigmoid - Bone coverage over the posterior semicircular canal and pneumatisation of the retro facial region (CSF leak risk). Position of the endolympathic sac.

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57
Q

What are the Electronystagmography (ENG)?

A

Electronystagmography - use to assess superior vestibular nerve function through cold and warm water (bi-thermic caloric testing in the ear causing nystagmus = (COWS) cold opposite warm same) . Note this only tests the horizontal semicircular canal.

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58
Q

Interpret this ENG result:

A

Reduced superior vestibular nerve function in the right ear on cold caloric testing.

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59
Q

What are VEMPs?

A

Vestibular evoked myogenic potentials. Most commonly recorded in SCM. These assess the inferior vestibular nerve through delivery of acoustic energy the saccule and is independent of hearing function so can be performed if completely deaf..

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60
Q

What are BAERs?

A

Brainstem auditory evoked responses. In VS results in prolonged I-III interpeak latencies. Useful for prognostication as poor wave morphology corresponds to lower chance of preserving hearing even with good pre-op hearing.

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61
Q

Which patients should be screened for a VS?

A

>10dB symmetric sensorineural hearing loss at >2 frequencies, asymmetric tinnitus (positive yield <1%!) or sudden sensorineural hearing loss in one ear.

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62
Q

What is the audible spectrum?

A

500-2k Hz

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63
Q

What do the X, O and triangles denote on a PTA?

A

X = Left

O = Right

and Triangle = bone conduction

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64
Q

How do you differentiate high freq hearing loss from a VS compared to hearing loss with age or loud noise?

A

VS hearing loss is asymmetric whilst other causes are symmetric.

Asymmetric sensorineural hearing loss >10 dB at two consecutive frequencies is indicative of a VS.

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65
Q

Which type of hearing loss has most effect on speech discrimination?

A

Retrocochlear hearing loss (note speech discrimination maintained with conductive hearing loss)

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66
Q

How is serviceable hearing defined?

A

Modified Gardener-Robertson - PTA loss <50 dB and speech discrimination >50% serviceable

Pragmatically: 1 = may use a phone on that side, 2 = can localise sound

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67
Q

Why are CISS/FIESTA useful for VS workup?

A

Visualise the course of the facial nerve and surrounding CNs if involved

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68
Q

What do hyperintense T2 regions of a VS suggest about the tumour?

A

That these tumours are softer and suckable so result in better CN VII function.

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69
Q

How do you grade the tumour extent of VS?

A

Using the Koos grading system:

1 = intracanalicular (<0.5 cc)

2 = Protrusion into CPA (<1 cc)

3 = Extends to brainstem but does not displace it (<2 cc)

4 = Displaces the brainstem and cranial nerves (4 cc)

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70
Q

What are the management options for VS?

A
  1. Conservative - watchful waiting
  2. Radiosurgery - single dose SRS with <13Gy is recommended for hearing preservation
  3. Surgery
  4. Biological therapies - Anti-VEGF (Avastin) for NF-2 related VS
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71
Q

Which VS have a faster growth rate with conservative management?

A

Those that expand outside of the IAC

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72
Q

Which tumours had a lower hearing preservation rate and high risk of CN7 injury?

A

>15 mm diameter

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73
Q

Which VS may demonstrate sudden and dramatic growth?

A

Cystic tumours

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74
Q

What are the CNS practice guidelines for the management of Koos 1 VS (intracanalicular) without tinnitus?

A

Observation - as these have a lower rate of growth and better hearing preservation.

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75
Q

What are the hearing preservation rates with SRS?

A

25-50% @ 10 years for serviceable hearing pre-SRS

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76
Q

Is there grade 1 evidence for the management of VS?

A

No!

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77
Q

What is your management algorithm for VS?

A

Koos 1/2 with intact hearing - conservative and treat only if >2 mm growth between 6 monthly MRI

Koos 3 - treatment with SRS or surgery

Koos 3/4 - Surgery to reduce the mass effect and decompress the brainstem

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78
Q

What is the difference in hearing preservation between SRS and surgery for VS?

A

At 5 years SRS is better but at 10 years it is the same. The hearing preservation with SRS is dependent on the amount of radiation given to the cochlear. With surgery experience and use of cochlear monitoring improves hearing.

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79
Q

What is the rate of facial nerve preservation?

A

98% overall with Koos 1-2.

With SRS it is also good if 13Gy is given (but not 20Gy)!

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80
Q

What is the risk of developing trigeminal neuralgia with SRS for VS?

A

7% with the higher dose of 20Gy, but no patients developed it if 13Gy was used.

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81
Q

What % of SRS treated VS increase in size?

A

20% show pseudo growth at 8 months, but the retreatment rate at 5 years was 4% (same as surgery)

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82
Q

How do you treat vertigo associated with VS?

A

Self limiting and improves with vestibular rehab exercises

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83
Q

Which surgical approaches are best for hearing preservation?

A

All should be treated by retrosigmoid except ff small and intracanalicular then middle fossa. Note middle fossa has a higher facial nerve palsy risk.

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84
Q

Which nerves should be monitored during VS surgery?

A

CN7 and 8. CN8 monitoring can be direct or via BAERs

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85
Q

What is the difference between serviceable and salvageable hearing?

A

Serviceable = 50/50 rule with PTA <50dB and >50% speech discrimination score

Salvageable hearing is whether serviceable hearing will be preserved post-op. This is unlikely if the pre-op speech discriminiation score <75%, PTA losses at >25%, tumour >2 cm or the pre-op BAER are abnormal.

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86
Q

Who performed the first VS resection?

A

First performed by Charles Ballance (NHNN) in 1894

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87
Q

Which direction is the facial nerve displaced with VS?

A

Forwards 75% >Inferior>Posterior

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88
Q

Where is the cochlear nerve found in VS surgery?

A

10% as a separate band on the tumour surface

90% within the tumour!

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89
Q

What is the goal of VS surgery if the tumour is tightly adherent to the CN7 or brainstem?

A

Subtotal / near-total resection leaving a small cuff on the nerve followed by SRS

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90
Q

How do you treat hydrocephalus associated with a VS?

A

VP shunt followed by surgery ~2 weeks later or EVD at start of surgery

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91
Q

Describe the translabyrinthine approach.

A

Supine head turn

Prep abdo for fat graft

C-shaped skin incision behind pinna to allow exposure of sigmoid

Mastoidectomy and preserve facial canal

Drill through vestibular apparatus behind and superior to CN7

The dura bounded by the sigmoid sinus, sup. petrosal sinus and deep to the labyrinthine is Trautman’s triangle.

Open the dura to get access to the posterior lateral brainstem.

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92
Q

Label the anatomy of the pre-sigmoid approach

A

A- Sinodural angle

B- Trautman’s triangle

C- Sigmoid sinus

D- Jugular bulb

E- Facial nerve (mastoid segment / tympanic segment)

F- Semicircular canal

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93
Q

How do you open the dura for a translabyrinithine approach?

A
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94
Q

Describe the retrosigmoid approach.

A

Lateral position - mayfield

Lumbar drain

C-shaped incision 3 cm behind the pinna

Identify asterion and then transverse-sigmoid junction with craniotomy

C- Durotomy with release to angle between transverse-sigmoid junction

Sacrifice the petrosal vein to allow cerebellum to fall away

Exposure to CPA and cisterna magna for CSF release

Identify tumour capsule and perform CN7 monitoring during resection

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95
Q

CT anatomy for approaches to VS

A

Important not to enter the Superior semicircular canal when entering the IAM during a retrosigmoid approach otherwise they will lose hearing. Drill anterior to the endolymphatic canal

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96
Q

Describe the middle fossa approach.

A

Lumbar drain

Head horizontal

6 cm incision starting ant to the tragus

4x3 cm craniotomy

Subtemporal extradural approach - section MMA and preserve the GSPN

Drill and expose the IAM from the meatus to Bill’s bar

Localise CN7 with stimulator

Open the dura over the IAM and dissect tumour from CN8

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97
Q

What are the routes for CSF leak following VS?

A
  1. Apical to the tympanic cavity (most common)
  2. Vestibule of the horizontal semicircular canal
  3. Posterior semicircular canal
  4. Perilabyrinithine cells > Mastoid air cells
  5. Mastoid air cells during craniotomy
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98
Q

Where is the vestibule of the semicircular canal?

A

Where all of the semicircular canals join. The oval window opens into the vestibule.

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99
Q

How do you manage facial nerve dysfunction following VS surgery?

A

Lacrilube, eye taping at night. If complete loss then tarsorrhaphy within a few days.

Facial reanimation with CN12-CN7 anastamosis 2 months after CN7 nerve was divided.

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100
Q

What is attached to the oval window?

A

The footplate of the stapes. Note: the round window is between the middle and inner ear and covered with a membrane.

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101
Q

What is the risk of malignant transformation with SRS for VS?

A

3 in 1000

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102
Q

What is a perineurinoma?

A

Tumour composed exclusively of neoplastic perineural cells. Causes pseudo-onion bulb formation with cylindrical enlargement of the nerve over 2-10 cm. Can be grade 1-3.

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103
Q

What % of MPNST are associated with NF1?

A

50%. In NF1 they tend to occur in plexiform or intraneural neurofibromas

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104
Q

What is the action of Bevacizumab?

A

VEGF inhibitor

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105
Q

What are the boundaries of Trautmann’s triangle?

A

Superior petrosal sinus above

Sigmoid sinus behind

Jugular bulb below

Semicircular canal anterior

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106
Q

What are the features of cystic VS?

A

More rapid growth

Frequent CN7 involvement

Unpredictable biological behaviour

Heamorrhage into the cyst esp after SRS may be associated with brainstem compression and obstructive hydrocephalus

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107
Q

Is there any difference in facial nerve palsy rates with approach to VS?

A

Middle fossa approaches are associate with a higher facial nerve palsy rate, but there is no difference between retrosigmoid and translabyrinthine approaches.

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108
Q

What HB grading has the best outcome from facial reanimation therapy?

A

HB3

Options include face-lift/eyelid tarsorrhaphy

facial anastomosis

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109
Q

What is the management of a parasellar meningioma causing visual impairment?

A

Decompression of the optic nerve

Resection of the extracavernous portion compressing the CN2

SRS to the remainder

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110
Q

What is the blood supply to anterior skull base meningiomas?

A

Ethmoidal arteries

Opthalmic A branches

ACA branches if very large

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111
Q

How do you differentiate chordomas and chondrosarcomas?

A

Indistinguishable on MRI. Classic soap bubble appearance. Chordomas arise from the midline whilst chondrosarcomas arise paramedian.

Chordomas sacral 50%, clival 35% and vertebral 15%

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112
Q

What jugular foramen syndromes affect CN9/10/11?

A

Vernet = 9/10/11

Collet-sicard = 9/10/11/12

Villaret = 9/10/11/12/Sympathetics

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113
Q

What are the contents of foramen lacerum?

A

Carotid

GSPN / Vidian nerve

Ascending pharyngeal artery

Emissary vein

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114
Q

What is a transcochlear approach?

A

Drilling of the superior and posterior EAM

The sacrifice of the semicircular canals and cochlear

Rerouting the facial nerve to access the CPA, petrous apex and ventral brainstem

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115
Q

What is the most common pituitary tumour?

A

Pituitary adenoma

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116
Q

How do pituitary tumours present?

A

Endocrinopathy, mass effect, headache, incidental finding and pituitary apoplexy

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117
Q

Which pituitary tumour is managed medically?

A

Prolactinoma with DA agonists (Cabergoline / bromocriptine / Quinagolide)

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118
Q

Pituitary carcinomas are invasive. Which hormones are they likely to secrete?

A

Prolactin or ACTH

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119
Q

What are the most common type of pituitary adenoma?

A

Non-functioning

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120
Q

Which familial syndrome is most commonly related to pituitary adenomas?

A

MEN1 - Autosomal dominant and also involves pancreatic islet cell tumours and parathyroid tumours. The pituitary adenomas are usually non-secretary.

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121
Q

Which hormones are secreted by adenomas?

A

PRL (48%), GH (10%), ACTH (6%) and TSH (1%)

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122
Q

How do prolactinomas present?

A

In Females - amenorrhoea-galactorrhea syndrome In Males - impotence

123
Q

What is the stalk effect?

A

Compression of the pituitary stalk results in loss of DA inhibition and a modest rise in prolactin

124
Q

What is the difference between Acromegaly and Gigantism?

A

Gigantism occurs before the closure of the epiphysis

125
Q

What is thyrotropin?

A

TSH

126
Q

How do FSH / LH secreting tumours present?

A

Usually clinically silent. FSH may cause amenorrhea-galactorrhea syndrome due to ovarian hyperstimulation

127
Q

Which hormones are likely to be deficient with pituitary adenomas?

A

Go Look For The Adenoma GH > LH > FSH > TSH > ACTH

128
Q

What does chronic panhypopituitarism cause?

A

Pituitary cachexia AKA Simmond’s cachexia - characterised by anorexia, amenorrhea, premature aging and low metabolic rate

129
Q

Selective single pituitary deficiency is rare with adenomas. What other diagnosis should be considered?

A

Autoimmune hypophysitis which commonly causes deficiency of ACTH or ADH - resulting in DI

130
Q

How does GH deficiency present?

A

In children with short stature

In adults with muscle loss, centripetal obesity and reduced exercise tolerance

Hypogonadism

131
Q

How does hypothyroidism present?

A

Weight gain

Hair loss / dry skin

Cold intolerance

Myexdema

Entrapment neuropathy (carpal tunnel)

Tiredness

Constipation

132
Q

What is Woltman’s sign o hypothyroidism?

A

Delayed relaxation of the ankle jerk

133
Q

What conditions are associated with DI at presentation?

A

Autoimmune hypophysitis

Hypothalamic glioma

Suprasellar GCT

Craniopharyngioma

134
Q

What is Kallmann syndrome?

A

Combination of anosmia and central hypogonadatrophic hypogonadism. MRI reveals a lack of olfactory bulb in 60%,

135
Q

What are the consequences of mass effect by a pituitary lesion?

A

Optic chiasm > bitemporal hemianopsia starting from the upper fields

Thrid ventricle > obstructive hydrocephalus

Cavernous sinus > Cranial neuropathy, proptosis, chemosis from venous congestion, encasement of carotids

CSF leak

Headache

136
Q

What is the definition of apoplexy?

A

Sudden expansion of a sellar mass causing neurological or endocrinological deterioration

137
Q

What causes expansion with apoplexy?

A

Haemorrhage, necrosis or infarction

138
Q

How does apoplexy present?

A

Headache

Visual disturbance (opthalmoplegia > VFD)

Loss of conciousness (raised ICP or hypothalamic involvement)

Cavernous sinus compression (Cranial neuropathy / venous congestion)

139
Q

What is the difference between Cushing’s syndrome and disease?

A

Cushing’s syndrome is a constellation of symptoms secondary to hypercortisolism.

Cushing’s disease is hypercortisolism secondary to an ACTH-secreting adenoma.

140
Q

What are the causes of endogenous hypercortisolism?

A

Pituitary adenoma (80%) - mildly elevated ACTH

Ectopic ACTH from lung ca (10%) - very elevated ACTH

Adrenal adenoma / carcinoma (10%) - low ACTH as directly secretes cortisol suppressing ACTH

Hypothalamic CRH release (very rare) - elevated ACTH

141
Q

Which carcinomas can release ectopic ACTH?

A

Small cell lung ca

Thymoma

Carcinoid tumours

Phaeochromocytomas

Medullary thyroid ca

142
Q

What is the gender predominance of Cushing’s disease?

A

10x more common in women

Note: Ectopic ACTH is 10x more common in men!

143
Q

What is more common, ACTH releaseing adenoma or Acromegaly?

A

Acromegaly is 4x more common than Cushing’s disease

144
Q

What is the difference between the types of pituitary adenomas in adults and children?

A

Cushing’s disease is more frequent in children and non-functioning is less frequent.

145
Q

What size are ACTH-releasing adenomas typically?

A

<5 mm in 50% of cases

146
Q

What are the clinical features of Cushing’s syndrome?

A

Hands - easy bruising, hyperpigmentation (if ACTH high), carpal tunnel, thin skin

Arms - prox. myopathy, hypertension, osteoporosis

Face - plethoric facies, hirsuitism, acne, depression, dementia

Body - centripetal obesity, buffalo hump, purple striae

147
Q

What are the laboratory findings with Cushing’s disease?

A

Hyperglycaema, hypokalemic alkalosis, loss of diurnal cortisol variation, inappropriately high or normal ACTH levels, high 24 hours urine free cortisol, failure to suppress with low dose dexamethasone test

148
Q

What is Nelson’s syndrome?

A

Occurs in 30% of patients that undergo bilateral adrenalectomies performed for Cushing’s disease which is performed when adenoma is non-resectable or failure of medical therapy after TSH.

Presents with hyperpigmentation (due to ACTH cross reactivity with MSH), high ACTH and progression of pituitary tumour

149
Q

What is the treatment for Nelson’s syndrome?

A

Resection of adenoma, Radiotherapy or Medications e.g. Metyrapone

150
Q

Why does Nelson’s syndrome occur after bilateral adrenalectomy?

A

Cortisol levels normalise > CRH levels rise > ACTH-releasing adenoma grows > high ACTH causes hyperpigmentation due to MSH corss reactivty.

151
Q

Why do you get testicular enlargement with Nelson’s syndrome?

A

Due to high ACTH stimulating hypertrophy of adrenal rest cells in the testes, which then secrete cortisol and in some cases return of Cushing’s disease despite adrenalectomy

152
Q

What is the management of pituitary apoplexy?

A

Hydrocortisone administration

Visual field assessment

Endocrine evaluation

Rapid surgical decompression is required for sudden constriction of the visual fields or deterioration in acuity.

Bills et al 1993 showed in a retrospective study of 37 patients that surgery within 7 days was better then after 7 days.

153
Q

What is the Mod. Hardy’s (Wilson) system for classification of pituitary adenoma extension / spread?

A

Extension

Suprasellar: A) In suprasellar cistern, B) Recess of 3rd ventricle obliterated, C) Floor of 3rd ventricle grossly displaced

Parasellar: D) Intrdural, E) Into cavernous sinus

Spread

I - sella <10mm, II sella >10mm

III - localised or IV - diffuse destruction of sella floor

V - spread via CSF

154
Q

What is the goal of transsphenoidal surgery in apoplexy?

A
  1. Decompress the optic apparatus, pituitary gland, cavernous sinus and third ventricle if hydrocephalus
  2. Histological diagnosis

Complete removal fo the tumour is not necessary

155
Q

What is Forbe’s Albright syndrome?

A

Amenorrhea-Galactorrhea syndrome secondary to prolactin-secreting pituitary tumour

156
Q

What is McCune Albright syndrome?

A

Polyostotic fibrous dysplasia

Cafe au lait spots

Precocious puberty

157
Q

What % of prolactinomas are microadenomas at diagnosis?

A

90% in women and 60% in men

158
Q

What % of GH are macroadenomas at diagnosis?

A

75%

159
Q

What work up is needed for a patient with acromegaly?

A

Endocrine

Opthalmology

Cardiac (cardiomyopathy)

Colonoscopy

160
Q

What are the criteria for biochemical cure in acromegaly?

A

Normal IGF-1, GH <5 ng/ml and GH nadir < 1 ng/ml after OGTT

161
Q

What are the causes of ectopic GH secretion?

A

Carcinoid tumours of the lung, pancreas and GI tract

162
Q

What % of GH-adenomas also secrete prolactin?

A

25%

163
Q

Which genetic syndromes are associated with acromegaly?

A

MEN-1, McCune Albright, familial acromegaly and Carney complex (PRKAR1A = protein kinase A regulatory subunit 1A)

164
Q

What are the clinical findings associated with acromegaly?

A

MNEMONIC: STDS ROC A PIMPS BENT GO BAC

Spade-like hands

Tremor

Diabetic testing marks

Sweating

Rings not fitting

Osteoarthritis - Heberden’s nodes

Carpal tunnel syndrome

Acanthosis nigricans

Prox. myopathy

Incisor spacing

Macroglossia

Prognathism

Supra-orbital riding

Bossing of frontal bone

Ears enlarged

Nose enlarged

Temporal hemianopia

Goitre

Organomegaly

Bowel cancer

Apnea sleep

Cardiomyopathy

165
Q

Why is life-expectancy reduced with untreated acromegaly?

A

Diabetes

Hypertension

Cardiovascular risk

Colon cancer

Sleep apnoea

166
Q

What cardiovascular complications occur in acromegaly?

A

Cardiomyopathy - reduced LV diastolic function, increased LV size, arrhythmias and fibrous hyperplasia of the connective tissue.

Hypertension exacerbates the cardiomyopathic changes

167
Q

What % of adenomas release TSH?

A

<1%

168
Q

What is the difference biochemically between primary and secondary hyperthyroidism?

A

Primary has high T4 and low TSH

Secondary has high T4 and high TSH

169
Q

What are the clinical symptoms of hyperthyroidism?

A

Anxiety

Palpitations

Atrial fibrillation / SVT

Heat intolerance

Hyperhidrosis

Weight loss despite increased food intake

170
Q

What are the clinical signs with hyperthyroidism?

A

Hyperactivity, lid lag, tachy, irreg heart rate, hyperreflexia and tremor. Exopthalmos and pretibial myxedema are only with Grave’s disease.

171
Q

What are the most common histologies with non-functional adenomas?

A

Null cell adenomas

Oncocytomas

Silent gonadotrophin / corticotrophin adenomas

172
Q

What is the most common tumours in the posterior pituitary?

A

METASTASIS due to the rich blood supply

173
Q

What is the acute management of apoplexy?

A

Pituitary profile

Empirical IV hydrocortisone if signs of addisonian crisis (haemodynamic instability)

VFD when stable.

Urgent TSH within 7 days should be performed if low conscious level or progressive visual field deterioration (not cranial nerve palsy from cavernous sinus compression).

174
Q

Can DI occur with primary adrenal insufficiency?

A

NO, you cannot diagnose DI unless the adrenal glands are functioning as the mineralocorticoid (aldosterone) is needed to concentrate the urine. Steroids can mask DI as they have mineralocorticoid effect.

175
Q

When are LH & FSH highest?

A

Mid-cycle

(FSH follicular 0.5-5, mid-cycle 8-33 and luteal 2-8)

(LH follicular 3-12, mid-cycle 20-80 and luteal 3-16)

176
Q

What is a predictor of hypopituitarism following apoplexy?

A

Low prolactin levels

177
Q

When do you check morning cortisol after transsphenoidal surgery?

A

Check 9 am cortisol on day 2 or 3 (omit the evening dose of hydrocortisone the night before).

If >550 nmol/l then does not need steroids

If 400-550 nmol/l then needs steroids when ill

If <400 nmol/l then commence steroid replacement

All hormones should be rechecked at 4-8 weeks

178
Q

How does the water deprivation test distinguish cranial and nephrogenic DI?

A

Serum osmo >290 i.e. becomes dry with water deprivation

If urine osmo fails to concentrate i.e. <300, but the administration of DDAVP does lead to urine concentration then this is a cranial cause i.e. lack of ADH release. If the DDAVP does not lead to urine concentration then this is a nephrogenic cause of DI as the kidney is unable to contrate the urine.

179
Q

What test should you perform in a patient with synchronous germinoma?

A

Serum and CSF B-HCG and AFP (as there may be non-germinomatous elements)

180
Q

How are BAERs performed?

A

An ear plug is placed in the ipsilateral EAC and clicking sounds are delivered.

A needle electrode is placed anterior to the tragus (anode) and at the vertex (cathode).

7 waves are generated within 10 ms of the click. Only the first 5 waves (ECOLI) are used clinically. Wave V is the most sensitive and any change in latency of V >0.5 seconds is indicative of disturbance.

181
Q

What is a normal response to a short synacthen test?

A

Levels should be >600 nmol/l after 30 mins otherwise the patient has primary adrenal insufficiency!

182
Q

Which hormone is most likely to be deficient in non-functioning adenomas?

A

FSH/LH

183
Q

What is a contraindication to GH therapy?

A

Active malignancy

184
Q

What is the gold-standard test for GH deficiency?

A

If IGF-1 level is low then dynamic testing with insulin tolerance test is required. This is contraindicated in those with IHD, epilepsy and obesity. In which case stimulation testing with GHRH-arginine test is needed.

185
Q

What prolactin levels are associated with a stalk effect vs a prolactinoma?

A

Normal levels are <100 ng/l or <2000 mIU/l

Stalk effect levels are <200 ng/l or <4000 mIU/l

Prolactinoma level are >200 ng/l or >4000 mIU/l

186
Q

How do you treat a non-functional pituitary adenoma with significant cavernous sinus invasion?

A

TSH to debulk the lesion and decompress the optic nerves

Ensure enough distance between the tumour and the optic nerves so that SRS can be given to the cavernous sinus residual tumour.

187
Q

Why does hypothyroidism result in raised prolactin levels?

A

As prolactin release is stimulated by high levels of TRH (which is elevated in hypothyroidism)

188
Q

Why should females starting bromocriptine/cabergoline also commence oral contraceptives?

A

As they will normalise the prolactin levels and restore fertility

189
Q

Why is the management of prolactinomas challenging during pregnancy?

A

As prolactin levels are unreliable.

Growth during pregnancy is 5% for micros and 15-40% for macros

190
Q

What is the significance of a hypointense area in the pituitary gland in a patient with Cushing’s syndrome?

A

This is a nonspecific finding that is also seen in 10% of normal patients. so IPSS should be performed to rule out ectopic ACTH secretion from a carcinoid tumour in the lung, adrenal or GI systems.

191
Q

What are the risks of untreated Cushing’s disease?

A

Cardiovascular events

Obesity

Infections etc

5x higher mortality with Cushing’s disease which is reversed with treatment.

192
Q

What are the options after failed TSH in Cushing’s disease?

A

Hemihypophysectomy or completion hypophysectomy

Medical treatments (metyrapone, ketoconazole, mitotane and etomidate)

Glucorticoid-R blocker (mifepristone)

Bilateral adrenalectomy (risk of Nelson’s syndrome)

193
Q

How do you diagnose Acromegaly?

A

Raised IGF-1

If unequivocal then needs an OGTT. If it fails to suppress GH to <1ng/ml then confirms GH-releasing adenoma.

194
Q

What are the boundaries of Trautmann’s triangle?

A

Superior petrosal sinus above

Sigmoid sinus behind

Jugular bulb below

Semicircular canal anterior

195
Q

What is the initial management of a patient with a CSF leak after TSH?

A

CT head to r/o hydrocephalus and subdurals

Abx if signs of meningitis

Flat bed rest (spontaneous resolution in 70%)

If fails to resolve spontaneously then lumbar drain +/- re-exploration.

If defect <1cm - fat plug

If larger needs cartilage graft / nasoseptal flap

196
Q

What are the MRI features of a Rathke’s cleft cyst?

A

T1 hyperintense cyst due to the proteinaceous content of the cyst fluid. Thin uniform wall which does not enhance.

197
Q

What are the features of cystic VS?

A

More rapid growth

Frequent CN7 involvement

Unpredictable biological behaviour

Heamorrhage into the cyst esp after SRS may be associated with brainstem compression and obstructive hydrocephalus

198
Q

What is a marginal sinus?

A

A sinus that runs on the inner aspect of the foramen magnum

199
Q

What SRS dose is given to vestibular schwannomas?

A

12Gy. Not 16 Gy is associated with facial nerve injury in 1/3!

200
Q

How do you perform a directed examination of the pituitary gland?

A

Endocrine hyperfunction (prolactin = amenorrhea / galactorrhea; thyroid = heat intolerance sweating etc; GH = acromegaly features; cortisol = cushing’s disease and hyperpigmentation) Endocrine loss of function (hypothyroid, addisons etc) Visual dysfunction (bitemporal hemianopia) Cavernous sinus defect (cranial nerve defects causing opthalmoplegia, proptosis and chemosis)

201
Q

What investigations would you perform in a patient with a suspected pituitary lesion?

A

Endocrine (8 am cortisol and 24 h urine free cortisol, prolactin, FSH/LH, testosterone (M) and oestradiol (F), IGF-1 and fasting glucose, T4 and TSH). Visual fields - Humphrey perimetry MRI +/- contrast pituitary

202
Q

Why do you perform both 8am cortisol and 24h urine free cortisol testing?

A

8 am cortisol if best to detect pituitary insufficiency 24h urine free cortisol if best to detect Cushing’s disease

203
Q

What is the other name for IGF-1?

A

Somatomedin-C

204
Q

What are the ways the visual fields can be tested?

A

Humphrey automated perimetry > Visual evoked potentials > OCT (document extent of damage to the optic disc)

205
Q

What does red light detection loss signify?

A

Desaturation of light is an early sign of chiasmal compression

206
Q

What is more common, a pre- or post-fixed chiasm?

A

Pre (8%) and post (4%). The rest are directly above the sella!

207
Q

What visual field loss is associated with a pituitary adenoma?

A

Bitemporal hemianopsia! If post-fixed then can have unilateral visual loss with junctional scotoma (pie in the sky) in the contralateral eye due to compression of Willbrand’s knee. If pre-fixed then may have homonymous hemianopia from compression of the ipsilateral optic tract.

208
Q

Which hormones should be replaced pre-op if found to be deficient?

A

Hydrocortisone and T4. Replaced hydrocortisone first otherwise the T4 may precipitate an Addisonian crisis.

209
Q

How does autoimmune hypophysitis present?

A

Single hormone loss and thickening of the pituitary stalk

210
Q

What does an 8AM cortisol <6 mcg/100 ml suggest?

A

Adrenal insufficiency.

211
Q

How is the diagnosis of Cushing’s disease made?

A

Urine 24 h free cortisol >3 times the upper limit of normal.

False positives with stress and chronic alcoholism.

212
Q

What further tests would you perform is T4 is low and TSH low?

A

TRH stimulation test.

Check baseline TSH, give TRH 500 mcg then check TSH after 30 and 60 mins.

If the TSH has not doubled by 30 mins then suggests pituitary thyroid deficiency. If TSH goes very high then suggest primary hypothyroidism

213
Q

How do you assess the gonadal axis?

A

FSH & LH as well as Testosterone (M) and estradiol (F).

214
Q

What does a Prolactin level >200 ng/ml suggest?

A

Macroadenoma

215
Q

When should prolactin levels be measured?

A

Mid-morning and not after stress which may falsely elevate it.

216
Q

What is the only pituitary hormone primarily under inhibitory control?

A

Prolactin (inhibited by Dopamine)

217
Q

What is the treatment of a raised Prolactin due to a stalk effect?

A

Remove the compression. Don’t start Bromocriptine!

218
Q

What is the Hook effect?

A

When the prolactin level saturates the assay resulting in a falsely low result. Requires the lab to run serial dilutions.

219
Q

What is macroprolactinaemia?

A

When the prolactin is bound to Ig and is biochemically non-functional

220
Q

How do you test for DI?

A

The concentration of urine with water deprivation test.

Further tests include measurement of ADH in response to infusion of hypertonic saline.

221
Q

Why does chronic primary hypothyroidism cause pituitary hyperplasia?

A

As the pituitary grows in response to a high TRH and TSH due to a lack of T4 negative feedback. A low/normal T4 with high TSH suggest primary hypothyroidism (i.e. problem with the thyroid gland).

222
Q

Why do non-functioning pituitary adenomas cause secondary hypothyroidism?

A

Mass effect. T4 and TSH are low. There is a reduced response to TRH stimulation.

223
Q

What causes:

  1. High TSH and High T4
  2. Low TSH and High T4
A
  1. Secondary hyperthyroidism
  2. Primary hyperthyroidism
224
Q

What are the causes of a high prolactin?

A

Pregnancy / lactation

Adenoma

Stalk effect

Drugs (metaclopramide / OCP / TCA / SSRIs / Verapamil etc)

Primary hypothyroidism

Empty sella syndrome

Ectopic secretion

Macroprolactinaemia

Renal / liver failure

225
Q

Which disease causes the ACTH response to CRH to be exaggerated?

A

Cushing’s syndrome

226
Q

What tests would you perform if the 24h urine free cortisol was unequivocal?

A
  1. Low dose Dexamethasone suppression test (give 1 mg Dex at 11 pm and measure cortisol at 8am). If the cortisol suppresses to <1.8 mcg/dl then Cushing’s syndrome is ruled out.
  2. 11 pm salivary cortisol (should be at its lowest point)
227
Q

How do you differentiate Cushing’s disease from ectopic ACTH secretion?

A

High dose Dexamethasone suppression test (give 8 mg at 11 pm and measure plasma cortisol at 8 AM).

In 95% of Cushing’s disease the ACTH level reduced by 50%. In ectopic causes, it does not suppress.

CT CAP

Metyrapone test - causes a rise in 11-deoxycortisol with Cushing’s disease

CRH stimulation test - causes a rise in ACTH and cortisol with Cushing’s disease but not with exogenous source

IPSS (baseline to peripheral ACTH >1.4:1 is consistent with Cushing’s disease)

228
Q

How is an IPSS performed?

A

Catheter placed in the IPSS and ACTH levels are measured at baseline and following CRH at 2, 5 and 10 minutes. Comparison between both sides may help lateralisation. Can lead to false lateralisation due to communication throught the intercavernous sinus.

229
Q

What is the compication rate of IPSS?

A

2% including puncture of the sinus wall

230
Q

How do you assess for Addison’s disease?

A

ACTH stimulation test (synacthin test) if 8am cortisol is low.

Measure baseline cortisol, given 250 mcg synacthin and then measure cortisol at 60 mins. If cortisol >20 mcg/dl then rules out Addisons. If <20 need steroid replacement.

If unequivocal then need to do insulin tolerance test. Insulin given to reduce the BM<4 and then measure cortisol. If <20 then need steroid replacement.

231
Q

How can Acromegaly be diagnosed?

A

IGF-1 level

Oral glucose tolerant test - 75 mg glucose given an GH levels measured every 30 mins for 2 hours. The GH level should fall to <1 ng/ml in normal cases.

Octreotide SPECT scan for diagnosis of ectopic GH secretion

232
Q

What is the normal size of the pituitary gland?

A

<9 mm (or <11 mm in females of childbearing age / puberity)

233
Q

What MRI should be requested for suspected pituitary adenomas?

A

Dedicated 3T MRI of the pituitary +/- contrast

If microadenoma then a dynamic MRI allows enhancement to be differentiated from the rest of the gland. Normally the gland enhances before the adenoma.

234
Q

Why does the posterior pituitary have high T1 signal (bright spot) without contrast?

A

High phospholipid content

235
Q

What does absence of the pituitary bright spot on T1 MRI suggest?

A

Corresponds with DI due to autoimmune hypophysitis

236
Q

What is the cause of a thickened pituitary stalk?

A

Lymphoma

Autoimmune hypophysitis

Granulomatous disease

Hypothalamic glioma

**note pituitary stalk is approx the same diameter as the basilar artery

237
Q

Why is a CT performed prior to transphenoidal surgery?

A

To demonstrate the nasal / sphenoid septal anatomy

238
Q

Should you treat hypothyroidism in a patient with pituitary adenoma?

A

Check for adrenal insufficiency first with synacthen test. Treat adrenal insufficiency first before giving thyroxine.

239
Q

How should you treat GH secreting tumours before surgery?

A

Somatostatin analogue before surgery to reduce the surgical risks (general and cardiac).

Then transphenoidal surgery.

240
Q

What is the recommended treatment for symptomatic non-functioning adenomas?

A

Surgery

Bromocriptine + octreotide may reduce size in 60% of cases

Radiotherapy is an effective adjunct for recurrent or residual disease

**Observation is only recommended for asymptomatic non-functioning adenomas

241
Q

What are the indications for surgery on a pituitary adenoma?

A

Mass effect

Endocrinopathy

Apoplexy

Diagnosis

Nelson’s syndrome (30% of cases of bilateral adrenalectomy develop high ACTH levels which causes pigmentation and enlargement of the pituitary adenoma)

242
Q

What are the side effects of Bromocriptine / Cabergoline?

A

Postural hypotension, dizziness, depression, nightmares and nasal congestion. Improved by bedtime dosing.

Starting bromocriptine can restore fertility but is teratogenic and can lead to spontaneous abortions.

243
Q

What is the difference between Cabergoline and Bromocriptine?

A

Bromocriptine is D1 and D2-agonist, whilst cabergoline is D2 only. The half life is longer with cabergoline so once weekly dosing.

244
Q

What side effect is associated with Cabergoline?

A

Cardiac valvular disease due to effect on fibromyoblasts which causes regurgitation due to valvular fibroplasia.

245
Q

How do you manage elderly patients with asymptomatic GH releasing adenomas?

A

Conservative

246
Q

How long do IGF-1 levels take to normalise after GH adenoma surgery?

A

Months. There is no defintion of a biochemical cure. Repeat surgery is usually not successful so medical therapy and radiotherapy may be needed as second-line.

247
Q

What are the medical management options for GH-adenomas?

A

Somatostatin analogues e.g. octreotide

GH antagonists - pegvisomant

248
Q

What are the side effects of octreotide?

A

Gallstones

Bradycardia

Diarrhoea / abdominal discomfort

249
Q

What is pegvisomant?

A

Genetically engineered GH-R antagonist

250
Q

What is the management of Cushing’s disease?

A

SURGERY if microadenoma is visible.

If not, then IPSS. Surgery on the side suggested by IPSS.

If IPSS is negative then look for ectopic source.

251
Q

What is the management if surgery for cushing’s disease is unsuccessful?

A
  1. Re-exploration / Completion hypophysectomy
  2. SRS if residual cannot be resected e.g. in cavernous sinus
  3. Medical therapy
  4. Bilateral adrenalectomy
252
Q

What is the difference between a low and high dose Dexamethasone test?

A

Low dose will only suppress cortisol from a normal gland not an adenoma. Suppression with low dose Dexamethasone rules out a CD.

High dose will suppress an adenoma but not an ectopic source.

253
Q

What are the medical treatment options for Cushing’s disease?

A

Ketaconazole - blocks adrenal steriod synthesis

Aminoglutethimide - prevents cholesterol to pregnenolone

Metyrapone - inhibits 11-beta hydroxylase preventing 11-deoxycortisol to cortisol

Mitotane - inhibits multiple steps in steroid synthesis

Ciproheptadine - seratonin-R antagonist

254
Q

What is the management for pituitary adenomas secreting TSH?

A

Surgery

Radiotherapy to residual

Medical therapy = octreotide. Causes tumour shrinkage in 1/3,

255
Q

What is the side-effect of radiotherapy to pituitary adenomas?

A

50% are panhypopituitary at 10 years.

May cause blindness due to optic nerve / chiasm injury

Mental / cognitive disturbance

Cranial nerve palsies

Apoplexy

256
Q

How long does radiotherapy take to work for acromegaly and Cushings?

A

10-20 years for Acromegaly and 1-2 years for Cushing’s

257
Q

When should stress doses be given to patients with pituitary adenomas?

A

During and immediately after surgery

258
Q

How should you reverse hypothyroidism pre-operatively?

A

Check HPA axis. Replace cortisol before T4. Replace T4 for >4 weeks prior to surgery ideally

259
Q

When is a transcranial pituitary resection required over a transphenoidal?

A

When there is extrasellar extension into the middle fossa or residual inaccessible tumour following transphenoidal surgery

260
Q

What are the transcranial routes to the pituitary?

A

Subfrontal - prechiasmal (better if chiasm post-fixed) Pterional - optico-carotid triangle

261
Q

Anatomy of the subfrontal route to the pituitary gland

A
262
Q

Anatomy of the subfrontal route to the pituitary gland

A
263
Q

What are the transcranial routes to the pituitary?

A

Subfrontal - prechiasmal (better if chiasm post-fixed) Pterional - optico-carotid triangle

264
Q

How do manage carotid injury during TSPH?

A

Signalled by profuse arterial bleeding

Pack off with surgicel/muslin

Inform anaesthetist

Stop operation

DSA to identify a pseudoaneurysm

265
Q

Steps of a TSPH

A

Supine / Mayfield / Neuronavigation

Elevate head 15 deg

Prep thigh for fat graft

C-arm lateral fluoro if not using neuronavigation

Direct (endoscopic) or Indirect (microscopic) approach to sphenoid

Midline opening of sella with drill and expand with rongeur (avoid opening into carotid)

X-opening of dura with #11 scalpel

Use ring cureetes to deliver tumour and remove with rongeur/aspirate

Deliver suprasellar component with valsalva or injecting saline into lumbar drain

After debulk of tumour dissect margins

266
Q

Where is the sphenoid ostium?

A

At the back of the middle turbinate

267
Q

Where is the sphenoid ostium?

A

At the back of the middle turbinate

268
Q

How do you perform a TSPH for Cushing’s disease without lesion on MRI?

A

Paramedian incision and exploration on the side with highest ACTH on IPSS. If negative then paramedian incision on the contralateral side then a midline incision. If no tumoru can eb identified then perform a hemihypophysectomy on the sied with highest ACTH.

Note adenomas are usually soft purple/gray whilst the normal fland is pink and firm.

269
Q

How do you close the sella defect after TSPH?

A

Fat graft

Fascial covering

Gasket closure with implant or septal cartilage

Fibrin glue

Nasoseptal flap

270
Q

How do you close the sella defect after TSPH?

A

Fat graft

Fascial covering

Gasket closure with implant or septal cartilage

Fibrin glue

Nasoseptal flap

271
Q

What hormonal complications may occur after TSPH?

A

DI (triple phase response = DI 24 hours, normalisation / siADH, DI long-term)

Addisonian crisis

Long-term hypopituitarism (TSH/ACTH/FSH/LH deficiency)

272
Q

What is secondary empty sella syndrome?

A

The chiasm retracts into the evacuated sella causing visual impairment

273
Q

Where is the blood supply to the chiasm?

A

From the ophthalmic A and sup. hypophyseal A which lie below the chiasm. Disrupting this whilst removing tumour may worsen vision.

274
Q

What are the post-operative consideration following TSPH?

A
  1. Fluid balance - perform urine specific gravity, serum and urine osmos and repeat Na daily or if the UO>250ml/h for 2 hours
  2. Antibiotics until removal of nasal packs on day 3-6
  3. Stress steroid administration

**Do not allow drinking through a straw to avoid negative pressure causing a CSF leak

275
Q

What are the action sites of medical therapies for Cushing’s disease?

A

Metyrapone inhibits 11-beta-hydroxylase

Ketaconazole inhibits 17-alpha-hydroxylase

Mitotane and etomidate inhibit desmolase

276
Q

What are the action sites of medical therapies for Cushing’s disease?

A

Metyrapone inhibits 11-beta-hydroxylase

Ketaconazole inhibits 17-alpha-hydroxylase

Mitotane and etomidate inhibit desmolase

277
Q

How do you manage DI post TSPH?

A

Replace losses PO or IV

If losses >400 ml/h x2 hours then send serum/urine osmolarities, urine SG and Na. If urine SG <1.003 then consider Desmopressin but be cautious about the triple-phase response.

278
Q

Why does the DI triple phase response occur?

A

Transient DI following surgery 12-36 hours due to post. pituitary injury

Normalisation / SIADH picture due to release of cells once they die

Long-term DI as no more cells to produce the ADH

279
Q

How do you manage steroid dosing post-TSPH?

A

Continue stress dosing for 48 hours. Stop the hydrocortisone for 24 hours then measure morning serum cortisol.

If morning cortisol >9 mcg/dl then normal.

If <9 mcg/dl then restart hydrocortisone and refer to endocrinology for assessment of ACTH reserve by undertaking short-synacthen test at 1 month. Note: in ACTH deficiency there is adrenal atrophy and becomes unresponsive to the synacthen so will not peak at >18 mcg/dl which is a normal response.

280
Q

What is the metyrapone test?

A

This is performed to assess the pituitary ACTH reserve. A synacthen test should be performed first to rule out primary adrenal insufficiency.

Metyrapone is an 11b-hydroxylase inhibitor and reduces cortisol production and subsequently increases upstream metabolites such as 11-Deoxycortisol.

Given 2-3 gram at midnight and measure serum 11-Deoxycortisol in the morning. If there is limited ACTH reserve the adrenals will be atrophied and the total 11-Deoxycortisol levels will be low.

281
Q

What % of pituitary tumours recur?

A

10%

282
Q

How do you monitor patients following TSPH?

A

MRI

Endocrine follow up at day 2, 6 weeks and 12 months and Na on day 2 and 7

Opthalmology f/u

283
Q

What treatment is given to residual adenomas secreting TSH?

A

Radiation

284
Q

What is the definition of cure with Cushing’s disease?

A

<50 mcg/l (but may be too stringent!)

If >50 then re-exploration may be advised.

Low dose Dexamethasone test is predictive of remission following surgery.

If you stop the steroids for 24 hours then 24-hour urinary free cortisol is helpful in determining cure rates/

285
Q

What are the outcomes for TSPH in acromegaly?

A

85% cure with adenomas <10 mm

(50% overall).

Patients not cured require life-long medical therapy. The greater the debulk the better the response to medical therapy!

286
Q

How do you assess cure for GH secreting tumours?

A

Oral glucose tolerance test (GH levels should suppress to <1ng/ml if cured).

287
Q

What are the post-operative consideration following TSPH?

A
  1. Fluid balance - perform urine specific gravity, serum and urine osmos and repeat Na daily or if the UO>250ml/h for 2 hours
  2. Antibiotics until removal of nasal packs on day 3-6
  3. Stress steroid administration

**Do not allow drinking through a straw to avoid negative pressure causing a CSF leak

288
Q

Where is the blood supply to the chiasm?

A

From the ophthalmic A and sup. hypophyseal A which lie below the chiasm. Disrupting this whilst removing tumour may worsen vision.

289
Q

What is secondary empty sella syndrome?

A

The chiasm retracts into the evacuated sella causing visual impairment

290
Q

What hormonal complications may occur after TSPH?

A

DI (triple phase response = DI 24 hours, normalisation / siADH, DI long-term)

Addisonian crisis

Long-term hypopituitarism (TSH/ACTH/FSH/LH deficiency)

291
Q

How do you perform a TSPH for Cushing’s disease without lesion on MRI?

A

Paramedian incision and exploration on the side with highest ACTH on IPSS. If negative then paramedian incision on the contralateral side then a midline incision. If no tumoru can eb identified then perform a hemihypophysectomy on the sied with highest ACTH.

Note adenomas are usually soft purple/gray whilst the normal fland is pink and firm.

292
Q

How do manage carotid injury during TSPH?

A

Signalled by profuse arterial bleeding

Pack off with surgicel/muslin

Inform anaesthetist

Stop operation

DSA to identify a pseudoaneurysm

293
Q

When is a transcranial pituitary resection required over a transphenoidal?

A

When there is extrasellar extension into the middle fossa or residual inaccessible tumour following transphenoidal surgery

294
Q

How should you reverse hypothyroidism pre-operatively?

A

Check HPA axis. Replace cortisol before T4. Replace T4 for >4 weeks prior to surgery ideally

295
Q

When should stress doses be given to patients with pituitary adenomas?

A

During and immediately after surgery

296
Q

What are the anaesthetic concerns when performing facial nerve monitoring?

A

No inhalational anesthetics or NMJ blockers (short-acting only)

297
Q

What muscles are recorded from with facial nerve monitoring?

A

Orbicularis oculi and orbicularis oris.

In addition to intermittent direct electrical stimulation, free-running EMG is also performed.

298
Q

What is the natural history of VS?

A

The growth of VS is variable but on average growth is around 2-4 mm/year. Cystic VS have the propensity to grow acutely as the cystic component may enlarge.

299
Q

How is speech discrimination tested?

A

Recordings of words are played to the patient.

The intensity level at which 50% of the words are accurately repeated is the “Speech reception threshold” and correlates with the PTA. Testing uses bisyllabic words (baseball etc)

Speech discrimination is tested using monosyllabic words presented at 40dB above the SRT. 50 words are presented and the % correct is noted.

300
Q

What is the acoustic (stapedial) reflex?

A

When noise is provided in one ear, both stapedial muscles will contract in normal circumstances. The frequency which this occurs in the threshold. This reflex arc tests the cochlear>CN8>brainstem>CN7>stapedial muscle contraction. Testing is done ipsilateral and contralateral so the location of the damage in the reflex can be identified. In VS the ipsilateral stapedial reflex is missing when sound is applied to the ipsilateral ear. Sound in the contralateral will make the ipsilateral stapedial muscle contract unless there is CN7 involvement.

301
Q

What questions do you ask to determine the anatomical site of facial nerve dysfunction?

A

Dry eye = prox to geniculate ganglion

Hyperacusis = prox to nerve to stapedius

Loss of taste = prox to cauda tympani

None of the above present = distal to cauda tympani

302
Q

Endonasal view for direct transphenoidal approach.

A
303
Q

What is the VS control rate with SRS?

A

>90%

FRCS Part 2 (17 decks)

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