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FRCEM Primary > Anatomy - Cranial Nerve Lesions > Flashcards

Anatomy - Cranial Nerve Lesions Flashcards

1
Q

Causes of injury to Olfactory (I) nerve

A

Blunt trauma
Frontal lobe tumour
Meningitis

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2
Q

Signs of olfactory (I) nerve damage

A

Reduced taste and smell to all but ammonia

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3
Q

Anatomy of olfactory (I) nerve

A

Bipolar neurones that pass through cribiform plate to the olfactory bulb

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4
Q

Anatomy of optic nerve (II).
Optic nerve fibres are…
The optic nerve route is

A

The axons of retinal ganglion cells
Fibres from the nasal part of the retina decussate and pass backwards in the optic tract to the lateral geniculate bodies. Here fibres of the optic radiation pass to visual cortex.

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5
Q

Visual field defects: Monocular blindness - lesion location

A

Lesions of one eye or optic nerve

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6
Q

Visual field defect: Monocular blindness - causes (2)

A

MS

Giant cell arteritis

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7
Q

Visual field defects: Bilateral blindness - causes (3)

A

Methyl alcohol
Tobacco amblyopia
Neurosyphilis

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8
Q

Visual field defects: Bilateral hemianopia - lesion location

A

Optic chiasm compression

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9
Q

Visual field defects: Bilateral hemianopia - causes (3)

A

Internal carotid artery aneurysm
Pituitary adenoma
Craniopharyngioma

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10
Q

Visual field defects: Homonymous hemianopia - lesion location

A

Half the visual field contralateral to the lesion in each eye. Lesion is behind the optic chiasm int he tract, radiation of occipital cortex (macular sparing)

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11
Q

Visual field defects: Homonymous hemianopia - causes (3)

A

Stroke
Abscess
Tumour

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12
Q

Optic neuritis presents with (4)

A

Pain on moving eye
Loss of central vision
Afferent pupillary defect
Papilloedema

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13
Q

Optic neuritis caused by (4)

A

Demyelination
Sinusitis
Syphilis
Collagen vascular disorder

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14
Q

Optic atrophy presents with (2)

A

Pale optic discs

Reduced acuity

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15
Q

Optic atrophy caused by (8)

A 
MS
Frontal tumour
Friedreich's ataxia
Retinitis pigmentosa
Syphilis
Glaucoma
Leber's optic atrophy
Optic nerve compression
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16
Q

Papilloedema presents with

A

Swollen discs

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17
Q

Papilloedema caused by (4)

A

Raised ICP
Retro-orbital lesion
Inflammation
Ischaemia

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18
Q

Anatomy of Oculomotor (III) nerve

A

From brainstem on
MEDIAL aspect of CRUS CEREBRI
passes forward between POSTERIOR CEREBRAL and SUPERIOR CEREBELLAR ARTERIES close to posterior communicating artery.
Pierces the DURA near the edge of the TENTORIUM CEREBELLI and passes through lateral part of cavernous sinus with nerve IV and VI to enter the orbit.

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19
Q

Oculomotor (III) nerve signs

A

Fixed dilated pupil that doesn’t accommodate
Progresses to ptosis
Progresses to complete internal ophthalmoplegia

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20
Q

Causes of oculomotor (III) nerve issues (8)

A 
Diabetes
Trauma
MS
Giant cell arteritis
Syphilis
Posterior communicating artery aneurysm
Idiopathic
Raised ICP ( uncal herniation through tentorium)
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21
Q

Oculomotor (III) palsy without dilated pupil caused by

A

Diabetes mellitus

Vascular

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22
Q

Early dilatation of pupil in oculomotor (III) nerve palsy implies

A

compressive lesion

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23
Q

Diplopia from an oculomotor (III) nerve lesion may cause

A

nystagmus

24
Q

Anatomy of the trochlear (IV) nerve

A

Passes backwards in the brainstem
decussates in anterior medulla
passes around the cerebral peduncle by the temporal lobe.
Enters cavernous sinus with II and VI
Enters the orbit to supply superior oblique

25
Q

Trochlear (IV) nerve signs

A

Diplopia due to weakness of down and in eye movements
Pure vertical diplopia
Patient compensates by tilting head down and to opposite side

26
Q

Trochlear (IV) nerve palsy causes (9)

A 
Trauma
Infarction secondary to hypertension
Raised ICP
Infection
Demyelination
Diabetic neuropathy
Cavernous sinus disease
Orbital tumour
Congenital defect
27
Q

Anatomy of the Abducens (VI) nerve

A

From the nucleus in the floor of the fourth ventricle, fibres pass forward in the pons and emerge to follow a long extracerebral course on the base of the brain, across the apex of the petrous temporal, through the cavernous sinus and thence to the orbit and lateral rectus.

28
Q

Abducens (VI) nerve signs (2)

A

Inability to look laterally

Eye is deviated medially because of unopposed action of medial rectus

29
Q

Abducens (VI) nerve palsy causes (7)

A 
Perhaps the most common is diabetic neuropathy
Demylination (MS)
TB
Pontine CVA
Cavernous sinus disease
Infections (meningitis)
Wernicke-Korsakoff Syndrome
30
Q

Abducens (VI) nerve causes of indirect damage

A 
Any process (e.g. brain tumour, hydrocephalus, haemorrhage, oedema) which exerts downward pressure on the brainstem, causing the nerve to stretch.
This type of injury can affect either side first.
31
Q

Which side would be affected by a right-sided tumour affecting Abducens (VI) nerve?

A

TRICK QUESTION
A right-sided tumour can produce either a right-sided or left-sided sixth nerve palsy as an initial sign. Thus a right-side sixth nerve palsy does not necessarily imply a right-sided cause.
Sixth nerve palsies are infamous as ‘false localising signs’.

32
Q

Anatomy of the Trigeminal (V) nerve

A

Forms three trunks: Opthalmic, Maxillary, Mandibular divisions.

    • The Mandibular contains both sensory and motor fibres.
    • There may be considerable individual variation int he exact areas of skin supplied.
    • Opthalmic division lies with III, IV and VI int he cavernous sinus and supplied the skin over the medial nose, forehead, eye (including corneal reflex).
    • Maxillary division passes through the cavernous sinus and foramen rotundem and joins with parasympathetic fibres to form the sphenopalatine ganglion (lactimation).
    • Mandibular division leaves the skull through the foramen ovale, carrying sensory fibres from the skin of the lower lip and chin up to and including the tragus and upper part of the pinna, and mucus membranes of the floor of the mouth, cheek and anterior two-thirds of the tongue [taste fibres join it from the chorda tympani branch of the facial nerve].
    • Motor fibres supply the masseter, temporalis, pterigoids.
33
Q

Trigeminal (V) nerve signs

A
    • Reduced sensation or dysasthesia over affected area
    • Weakness of jaw clenching and side-to-side movement.
    • If there is a LMN lesion, the jaw deviates to the weak side when the mouth is opened.
    • There may be fasiculation of temporalis and masseter.
34
Q

Trigeminal (V) nerve palsy causes

A
    • Sensory
      • Trigeminal neuralgia
      • Herpes zoster
      • Nasopharyngeal carcinoma
    • Motor
      • Bulbar palsy
      • Acoustic neuroma
35
Q

Anatomy of Facial (VII) nerve

A
    • Mainly motor (some sensory fibres from external acoustic meatus, fibres controlling salivation and taste fibres from the anterior tongue).
    • Fibres loop around the VI nucleus before leaving the pons medial to VIII and passing through the internal acoustic meatus.
    • It passes through the petrous temporal in the facial canal, widens to form the geniculatr ganglion (taste and salivation) on the medial side of the middle ear, whence it turns sharply (and the chord tympani leaves) to emerge through the stylomastoid foramen and passes through the parotid gland to supply the muscles of the facial expression.
36
Q

Facial (VII) nerve signs

A
    • Facial weakness
    • In an LMN lesion the forehead is paralysed - the final common pathway to the muscles is destroyed
    • The upper facial muscles are partially spared in an UMN lesion because of bilateral innvervation in the brainstem.
37
Q

Facial (VII) nerve palsy causes

A
    • LMN
      • Bell’s Palsy
      • Polio
      • Otitis media
      • Skull fracture
      • Cerebello-pontine angle tumours
      • Parotid tumours
      • Herpes zoster (Ramsay-Hunt syndrome)
      • Lyme disease
    • UMN
      • Stroke
      • Tumour
38
Q

Anatomy of the Vestibulocochlear (VIII) nerve

A

Carries 2 groups of fibres:

  • Those to the cochlea (hearing) and to the semi-circular canals, utricle and saccule (balance and posture)
  • They pass together with the facial nerve from the brainstem across the posterior fossa to the facial nerve.
39
Q

Vestibulocochlear (VIII) nerve signs (4)

A
  • Unilateral sensorineural deafness
  • Tinnitus
  • Nystagmus
  • Vertigo
40
Q

Vestibulocochlear (VIII) nerve palsy causes (11)

A
  • Loud noise
  • Paget’s disease
  • Ménière’s disease
  • Herpes zoster
  • Neurofibroma
  • Acoustic neuroma
  • Brainstem CVA
  • Lead
  • Aminoglycosides
  • Furosemide (frusemide)
  • Asprin
41
Q

Anatomy of the Glossopharyngeal (IX) nerve

A
    • Contains sensory, motor (stylopharyngeus only) and parasympathetic fibres (salivary glands).
    • Passes across the posterior fossa through the jugular foramen and into the neck supplying the tonsils, palate and posterior third of the tongue.
42
Q

Glossopharyngeal (IX) nerve signs

A

The gag-reflex, as it is responsible for the afferent limb of the reflex

43
Q

Glossopharyngeal (IX) nerve palsy causes (5)

A

(Single nerve lesions exceedingly rare)

  • Trauma
  • Brainstem lesions
  • Cerebello-pontine angle and neck tumours
  • Polio
  • Guillain-Barre
44
Q

Anatomy of the Vagus (X) nerve

A
    • Contains motor fibres (to the palate and vocal chords), sensory components (posterior and floor of external acoustic meatus) and visceral afferant and efferent fibres.
    • It leaves the skull through the jugular foramen, passes within the carotid sheath in the neck (giving off cardiac branches and the recurrent laryngeal nerves supplying the vocal chords), through the thorax supplying lungs and continues on via the oesophageal opening to supply the abdominal organs.
45
Q

Vagus (X) nerve signs

A
    • Palatal weakness can cause ‘nasal speech’ and nasal regurgitation of food.
    • The palate moves asymmetrically when the patient says ‘Ah’ - uvula deviates away from the side of the lesion.
    • Recurrent nerve palsy results in hoarseness, loss of volume and ‘bovine cough’.
    • There is also dysphagia and loss of gag reflex.
46
Q

Vagus (X) nerve palsy causes

A
  • Single nerve lesions exceedingly rare.
  • Trauma
  • Brainstem lesions
  • Tumours in cerebello-pontine angle, jugular foramen and neck.
  • Polio
  • Guillain-Barre
47
Q

Anatomy of the Accessory (XI) nerve

A

Unique in that it originates outside the skull, enters via the foramen magnum and leaves via the jugular foramen to supply motor to sternocleidomastoid and trapezius.

48
Q

Accessory (XI) nerve signs

A

Weakness and wasting of sternocleidomastoid and trapezius.

49
Q

Accessory (XI) nerve palsy causes (6)

A

(Same as Vagus (X) nerve)

  • Single nerve lesions exceedingly rare.
  • Trauma
  • Brainstem lesions
  • Tumours in cerebello-pontine angle, jugular foramen and neck.
  • Polio
  • Guillain-Barre
50
Q

Anatomy of the Hypglossal (XII) nerve

A

It passes briefly across the posterior fossa, leaves the skull through the hypoglossal canal and supplies motor fibres to the tongue and most of the infrahyoid muscles.

51
Q

Hypglossal (XII) nerve signs (3)

A
  • Wasting of the ipsilateral side of the tongue.
  • Fasiculation.
  • On attempted protrusion, tongue deviates towards affected side.
52
Q

Hypglossal (XII) nerve palsy causes

A

(RARE)

  • Polio.
  • Syringomyelia TB.
  • Median branch thrombosis of the vertebral artery.
53
Q

Combined cranial nerve lesions

VII (Facial), VIII (Vestibulocochlear) then V (Trigeminal) and sometimes IX (Accessory)

A

Cerebello-Pontine tumours

54
Q

Combined cranial nerve lesions

– V (Trigeminal), VI (Abducens) [Gradenigo’s syndrome]

A

Lesions within petrous temporal bone

55
Q

Combined cranial nerve lesions

– Combined III (Oculomotor), IV (Facial) and VI (Abducens) (13)

A
    • Combined III (Oculomotor), IV (Facial) and VI (Abducens):
    • Stroke
    • Tumours
    • Wernicke’s Encephalopathy
    • Aneurysms
    • MS
    • Myasthenia gravis
    • Meningitis
    • Muscular dystrophy
    • Myotonic dystrophy
    • Cavernous sinus thrombosis
    • Guillain-Barre
    • Cranial arteritis
    • Trauma and orbital pathology
56
Q

Conditions that can affect any cranial nerve (8)

A
  • Diabetes mellitus
  • Multiple sclerosis
  • Tumours
  • Sarcoid
  • Vasculitis (e.g. polyarteritis nodosa)
  • Systemic lupus erythematosus
  • Syphylis
  • Chronic meningitis (malignant, TB or fungal)

FRCEM Primary (32 decks)

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