Random Extra Neuro Flashcards
How is neurofibromatosis inherited?
Autosomal dominant inheritance
Expression variable in NF1
50% of NF2 are de novo
Prevalence of neurofibromatosis type 1 and 2
NF1 = 1 in 2500 NF2 = 1 in 35,000
Signs of NF1 x7
1) Cafe au lait spots - seen in 1st year of life and increase in number with age
2) Freckling - especially in skin folds - axillae, groin, neck base - usually present age 10
3) Dermal neurofibromas - small, violet, gelatinous nodules - appear at puberty and no increase with age. Not painful but may itch.
4) Nodular neurofibromas - arise from nerve trunks - firm and clearly demarcated- paraesthesia if pressed
5) Lisch nodules - brown/translucent mounds on iris - develop by age 6 in 90%
6) Short stature
7) Macrocephaly
Complications of NF1 x5
Arise in 30%
1) Mild learning difficulty
2) Local effects of fibromas
- Neuro = weakness, pain and paraesthesia
- GI - bleeds, obstruction
- Bone - cystic lesions, scoliosis, pseudarthrosis, high BP
3) Plexiform neurofibromas (huge subcutaneous swellings)
4) Malignancy - 5% - Optic glioma, sarcomatous change of neurofibroma
5) Slight increase risk of epilepsy
Management of NF1
Yearly measurement of BP
Cutaneous survey yearly
Excision of dermal neurofibromas if troublesome
Features of NF2
Fewer cafe au lait spots than NF1
Bilateral vestibular schwannoma (acoustic neuroma)
- Present in 20s
- Sensorineural hearing loss is first sign
- Tinnitus, vertigo
- Benign but press on local structures and raise ICP
Juvenile Posterior subcapsular lenticular opacity - opacity in the eyes - occurs before other changes
Complications of NF2
Schwannomas of cranial and peripheral nerves and spinal nerve roots
Meningiomas (45% - often multiple)
Glial tumours
Management of NF2
Yearly hearing tests
MRI if abnormality
Clear scan at age 30 indicates gene has not been inherited (unless family Hx of late onset)
Surgery to remove vestibular schwannoma but risk of deafness and facial palsy
Mean survival from Dx of NF2
15 years - best practise can be better
What is Schwannomatosis?
Tender cutaneous schwannomas without vestibular schwannoma
DDX - Mosaic NF2 - vestibular schwannomas also absent - analysis of tumour biopsy for DX
Typically large tumour load - seen on MRI
Life expectancy is normal
Route of spinothalamic tracts
Pain and temp
Immediately decussate on entering spinal cord
Therefore lesion will cause contralateral pain and temperature loss
Route of dorsal columns
Fine touch, proprioception and vibration
Fibres decussate in the medulla (medical leminiscus)
Therefore lesion will cause ipsilateral loss
Motor pathways
Decussate in medulla in pyramidal decussation
Therefore ipsilateral UMN defect if spinal cord lesion
UMN damage signs
Spastic paraparesis
Babinski’s positive
Hyperreflexia
Increased tone
Damage to sphincters in spinal cord lesions
Early in intrinsic lesions
Late in extrinsic lesions
What is Brown-Sequard Syndrome
Rare unilateral cord lesion
Ipsilateral UMN signs, fine touch, vibration and proprioception
Contralateral pain and temp loss
Sensory occurs a few levels below motor
What happens in complete transection of spinal cord
1) Initial phase has spinal shock - loss of all reflexes, flaccid limbs, atonic bladder (overflow incontinence), atonic bowel, loss of vasomotor control
2) 1-2 weeks later, spasticity develops including spastic bladder (small capacity, urgency and frequency increased), hyperactive autonomic function
What occurs in partial transection of spinal cord?
Loss of function occurs within hours due to secondary oedema
Therefore give high-dose corticosteroids (dexamethasone) to reduce spinal cord oedema
Also stabilise spine and treat any fracture
What will compression of spinal cord cause
If below T1 - arms not affected
C5-T1 -LMN and sometimes UMN in arms and UMN in legs
Above c5 - UMN in legs and arms
Sphincter function usually preserved until late severe disease
Causes of compression of spinal cord
1) Trauma
2) Disc protrusion (spondylosis)
3) Spinal cord tumours (meningioma, neurofibroma, extradural)
4) Inflammatory lesions (epidural abscess - + fever, back pain - antibiotics and surgical drainage)
(tuberculoma - tb meningitis might be present)
What are syringomyelia and syringobulbia?
Fluid filled cavity in spinal cord and brainstem
Can be related to Arnold-Chiari malformation - cerebellar tonsils in FM - non-communicating hydrocephalus
Presentation age of syringomyelia
Usually 30s
Presentation of syringomyelia?
Pain in upper limb
Cape-like, dissociated sensory loss (dermatomes above and below are preserved)
Wasting or weakness of small muscles of hand - T1 common site for syrinx
Uni or bilateral horner syndrome - damage of sympathetic fibres within spinal cord down to T1
Spastic paraparesis if expands enough
Symptoms of vasovagal syncope
Reflex bradycardia + peripheral vasodilation provoked by emotion, fear, standing too long, pain
Onset over seconds, nausea, pallor, sweating and closing in of visual fields
Cannot occur if lying down
Fall to ground - may be jerking, unconscious for about 2mins
Urinary incontinence uncommon but can occur, No tongue-biting, recovery is rapid
EGs of situational syncope
Cough, effort (exercise, cardiac origin), micturition (men at night)
What are Stokes-Adams attacks?
Transient arrhythmias causing drop in CO and LOC
No warning except palpitations
Slow or absent pulse
Recovery in seconds
What are drop attacks?
Typically elderly woman - weakness of legs causes patient to drop to the ground
No warning or LOC, no confusion afterwards
Condition is benign and resolves after a few attacks
Symptoms of vertigo
Spinning is rare
Floor may tilt, sink or rise
Illusion of movement - usually rotatory
Always worsened by movement
Relieving factors in vertigo
Lying still or sitting down
Associated symptoms with vertigo
Nausea, vomiting, pallor, sweating
What is not vertigo?
Faintness (palpitations, tremor)
Lost awareness
Light-headeness
Causes of vertigo
If tinnitus and deafness - labyrinth or CN VIII involvement Trauma VZV Menieres disease Benign positional vertigo Acute labyrinthitis Acoustic neuroma - vestibular schwannoma Ototoxic drugs
What is benign positional vertigo?
Due to canalolithiasis
Head movement causes momentary vertigo
Nystagmus when perform Hallpikes manoeuvre
Treated with Epley manoevures
Signs of acute labyrinthitis?
Abrupt onset
Severe vertigo, nausea, vomiting and prostration
No deafness or tinnitus
Complete recovery takes 3-4 weeks but vertigo subsides in days
What is Menieres disease?
Vertigo lasting >20mins with fluctuating sensorineural hearing loss and tinnitus
Bed rest and reassurance with acute attack
Anithistamine - cinnarizine - useful if prolonged
Can do surgery if very severe
Ototoxic drugs?
Aminoglycosides, loop diuretics, cisplatin
Investigations in SAH
CT initially
Followed by 12h lumbar puncture to look for xanthochromia (yellowing of CSF with bleed from SAH)
