Cranial Nerve and Brain Stem Disorders Flashcards
What cranial nerves would be involved in : • Diplopia, pupil asymmetry, ptosis
3,4,5
What cranial nerves would be involved in • Sensory loss over the face
5
What cranial nerves would be involved in Weakness over the face only
7
What cranial nerves would be involved in vertigo (spinning)
8
What cranial nerves would be involved in hearing loss and tinnitus?
8
What are some signs common in brain stem and cranial nerve disorders but not unique to them?
Dysphagia (trouble swallowing)
Dysarthria (difficulty speaking)
In optic neuropathies, what occurs in OPTIC NEURITIS?
Commonest aetiology in the young, treatable
T cell immune mediated inflammation of the nerve, often with demyelination
Rapid onset of progressive visual field loss
Often painful, usually monocular, reds go pale
Disc can look normal (40%) if retrobulbar (ie if inflammation is behind the disc)
Lasts weeks-months, with variable outcomes
Important, as it is associated with eventual MS in 50% (higher change if there are multiple lesions on MRI brain & oligoclonal bands in CSF), and less commonly neuromyelitis optica (another autoimmune demyelinating disorder with spinal cord abnormalities)
When isolated, can be a “postinfectious” immune response following viruses like EBV, measles, mumps, influenze, etc
Common & treatable (steroids help)
What occurs in Ischaemic Optic Neuropathies0 what are the two broad types?
Non arteritic- large vessels arent involved- ie. small vessel occlusions, associated with small vessel occlusive diseases like diabetes, HTN, smoking
Arteritic ischaemia - large vessels are involve- can get inflammation of one of the large arteries
WHat are some less common causes of optic neuropathies?
- Infections – CMV, HIV, cat scratch disease, toxoplasmosis, syphilis, TB, Cryptococcus
- Systemic autoimmune & inflammatory diseases – SLE, Sjorgens, Wegener’s, IBD, sarcoidosis
- Nutritional deficiencies – B1, B12, folate
- Drugs – cyclosporine, chemotherapies, infliximab, bevacizumab, sildenafil
What are some helpful tests for optic neuropathies?
o MRI brain with gadolinium – nerve enhances if acute & inflammatory
o CSF – inflammatory? Viral PCRs, cultures
o Specialist blood tests if putative cause – antibodies, serology, gene tests etc
What are some of the causes of optic nerve compression and infiltration?
- Tumour of II nerve – gliomas (associated with neurofibromatosis)
- Tumours compressing II n - Meningioma, craniopharyngioma, pituitary adenoma, metastases
- Other –
- Grave’s ophthalmopathy (with hyperthyroidism)
- Carotid-ophthalmic artery aneurysms, abscess, cerebral venous thrombosis - Idiopathic intracranial HTN
- Increasingly common, more in females & obese
- Cause unknown, but factors include impaired CSF absorption, sleep apnoea, elevated venous pressure
- Visual loss via high pressure on optic nerves
- Associated with generalized headache, visual obscurations, papilloedema
What is the diagnostic approach to Optic nerve compression and infiltration
- CT or MRI brain will identify most masses
- Add CTV/MRV where cerebral venous thrombosis is possible
- LP for opening pressure where imaging normal & idiopathic intracranial HTN suspected
CNVI palsy
horizontal diplopia, cant abduct, turn head towards missing side.
Causes:
idiopathic, traumatic (post head injury), compression via tumour, aneurysm
CNIII palsy
Vertical and horizontal diplopia
eye sits in a ‘down and out’ position.
Causes: Ischemic; compresison in subarachnoid space (aneurysm of posterior communicating arter), tumour, meningococal etc
Other Ophthamogplegias/DDx of nerve palsies you must consider
NMJ disorders (seen in myasthenia gravis)
- occulomotor disorder (graves disease- hyperthyroidism)
- Internuclear ophthalmoplegia
- wernickes encephalopathy
What nerve would you be considering if they had facial numbness?
CN V - trigeminal
What is trigeminal neuralgia- what is the clinical context?
• Common
• Brief episodes of severe shock-like pain along one or more of the V nerve branches (usually V2 or V3 along the jaw)
• Doesn’t usually wake at night
• There are triggers – touching, chewing, brushing teeth or cold air
• Usually no signs (diagnosis based on history)
Causes:
***Compression of trigeminal nerve root by aberrant vessel (80-90%)
• Compression by tumour, aneurysm, AVM
• Multiple sclerosis
Need to MRI
Facial Motor Disorders- > eg Bells Palsy
CNVII
• Idiopathic unilateral LMN facial paralysis
o (?HSV infection in nerve ganglion)
• Rapid onset (over hours)
• Pain behind the ears rapidly develops into facial palsy
• Often preceding pain behind the ear, hyperacusis (CNVII controls small ear muscles that may have a role in dampening sound) and sometimes also impaired facial sensation (altered perception by droopy muscles, or true V involved)
Diagnostic approach to facial motor disorders
• Confirm LMN not UMN, but remember a LMN can still be in the brainstem (VII nucleus)
o LMN palsy affects whole side of face
o UMN affects contralateral lower ½ of the face
• Look for vesicles in ear (treatable HZV), parotid mass
• CT/MRI if tract signs, vertigo, diplopia etc
Vertigo: Vestibular Disorders- what are some common peripheral causes of Vertigo
Benign Paroxysmal Positional Vertigo
Meniere’s Disease.
Vestibular neuronitis and labrynthitis
Infections, drugs, autoimmune, alcohol, trauma etc
Describe Benign Paroxysmal Positional Vertigo
Benign Paroxysmal Positional Vertigo - commonest chronic and recurent cause: loose CaCo3 crystals in utricular sac in semicircular canal (idiopathic, Meniere’s disease), episodes last 30-40 seconds, chronic.
Describe Meniere’s disease
• Increase in endolymph fluid in the semicircular canals, with episodes of rupture of membranous labyrinth dumping endolymph into perilymph, but uncertain
• Background of sensorineural hearing loss (effecting the cochlear as well) +/- low pitched tinnitus
o If no hearing loss within 12 months or vertigo onset, unlikely meniere’s
• Episodes of horizontal vertigo for 20 mins – 24 hours, often with decreased hearing, increased tinnitus, and aural “fullness”
Describe some common CENTRAL causes of vertigo
TIA, stroke, haemorrhage in the brain stem or cerebellum
Encephalitis
Migraine vertigo
Describe the diagnostic approach to vertigo
Check it is vertigo
- Time course helpful
- acute- more central
Recurrent but infrequent: menierres, BPPV, etc
Chronic- BBP, … - Duration helpful
-seconds: BPPV
- Minutes: migraine
Hours: menieres, migraine
Days: vestibular neuritis, stroke - are brain stem/brain features present: likely central: show changes in speech, nystagmus, sensory loss, etc.
Dysphagia- What are the causes?
Structural/GIT - ie. not neurological
Myopathies involving pharyngeal/oesophageal mm
NMJ disorder: myasthenia gravis
Neuropathies and lesions involving CNIX, X
Brain stem disorders affecting CNIx//X nucleii
Cerebral disorders
Dysphagia
What are structural/GIT causes?
• Ie not neurological
• Eg: pharyngeal pouch, oesophageal web, ulcerative oesophagus, tumour etc
• Need gastroscopy &/or barium/video swallow to exclude first
• Note on history: sensation of food getting stuck, whereas neurological/oropharyngeal report difficulty initiating swallowing, with coughing, choking or nasal regurgitation, and that fluids are as problematic as solids!
o Neuro – liquids & solids
o Structural – big solids are the issue
Dysphagia
What myopathies involving pharyngeals/oesophageal mm?
- Dermatomyositis & polymyositis
- Myotonic dystrophy
- Oculopharyngeal muscular dystrophy
Dysphagia
What are some neuropathies & lesions involving CNIX, X
- Guillian-Barre syndrome
- Motor neuron disease, polio
- Head & neck masses (tumours, LNs, abscesses)
WHat are brain stem disorders affecting CNIX/X
- Multiple sclerosis
- Strokes, tumours
- Rhombencephaliis etc
- i.e. look for other signs of brain stem dysfunction
Multiple Cranial Nerve Disorders
There are many regions where cranial nerves group together, so masses, trauma or infection (of nerves or mennges) at these sites produce combined problems – eg:
hich nerves are in the RETROSPHENOID SPACE?
II III IV VI V1
Multiple Cranial Nerve Disorders
There are many regions where cranial nerves group together, so masses, trauma or infection (of nerves or mennges) at these sites produce combined problems – eg:
which nerves are in the CAVERNOUS SINUS
III
IV
VI
V1-2
Multiple Cranial Nerve Disorders
There are many regions where cranial nerves group together, so masses, trauma or infection (of nerves or mennges) at these sites produce combined problems – eg:
which nerves are in the JUGULAR FORAMEN
IX
X
XI
BRAIN STEM DISORDERS
General
- Brain stem includes cranial nerve nuclei, but also multiple sensory & motor tracts, connections to cerebellum & vital centres for attention, cardiac & respiratory centres
- Therefore, multiple symptoms/signs, plus can be coma & cardiorespiratory dysfunction
BRAIN STEM DISORDERS
Common Symptoms/Signs
- Reduced conscious state – via dysfunction of reticular activating state, although any diffuse severe cerebral disorder can produce this
- Nausea/vomiting – dysfunction of area postrema of medulla, but also occurs by cerebral disorder
BRAIN STEM DISORDERS
Uniqu signs and symptoms
Locked in syndrome – where bilateral motor tracts to limbs, trunk & face are affected, except can blink & move eyes → via base of pons lesion
‘Ataxic‘ irregular breathing
o If with hypertension & bradycardia → Cushing’s Triad of herniation of brain onto brainstem by increased ICP
Abnormal limb/trunk positioning
o Involuntary flexion or extension of the arms & legs, indicating severe brain injury
o Occurs when one set of muscles becomes incapacitated while the opposing set is not, and an external stimulus ie pain causes the working set of muscles to contract
Decorticate position
o Lesion above the red nucleus in midbrain
o Flexion of elbows & wrists + Adduction of arms
o Extension of legs, plantar flexion of feet + Feet turned inward
Decerebrate position
o Lesion below red nucleus in midbrain
o Arms adducted, extended, pronated & wrists flexed
o Legs extended, plantar flexed
AGAINST BRAIN STEM PATHOLOGY
COGNITIVE DEFECTS- eg dysphagia
SEIZURES
Name some Brain stem disorders
Brain stem strokes Brain Stem tumours Brain stem rhombencephalon- encephalitis Other (effect also lesion elsewhere) - MS - Osmotic demyelination
Common Brainstem tumours
o Glioma – usually unresectable
o Acoustic neuroma – actually a tumour of the Schwann cells of VIII nerve, present with SN hearing loss, tinnitus, unsteadiness (vertigo unusual as grow slowly)
• Curative resection possible
• Diagnose via CT/MRI (+/- Biopsy if able, as risky)
Describe Brainstem/rhombencephalon encephalitis?
• Inflammation of the brainstem +/- cerebellum via: o Infections (often with fever) • Listeria, enterovirus 71, HSV, EBV, VZV o Paraneoplastic antibodies • From SCLC, testicular CA, breast CA o Other autoimmune (SLE) • Diagnose via MRI & CSF (inflammatory) • DDX often tumour, lymphoma, MS
Describe brain stem/ rhombencephalon encephalitis
• Inflammation of the brainstem +/- cerebellum via: o Infections (often with fever) • Listeria, enterovirus 71, HSV, EBV, VZV o Paraneoplastic antibodies • From SCLC, testicular CA, breast CA o Other autoimmune (SLE) • Diagnose via MRI & CSF (inflammatory) • DDX often tumour, lymphoma, MS
