Neuro Flashcards
Leg dermatomes
L2 - mid thigh L3 - over the top of the knee L4 - medial calf L5 - lat calf S1 - edge of dorsum foot
Then do stocking distribution
vibration sensation
Test on most distal bony prominence and assess when stops, work up if cannot feel
polyneuropathies that are predominantly motor
GBS, lead poisoning, Charcot Marie tooth
causes of sensory-motor peripheral neuropathy
Metabolic causes: • Diabetes (most common) • hypothyroidism • vitamin deficiencies such as B1, B6 and B12 • uremia
Toxic causes: • alcohol (most common) • chemotherapy agents • antibiotics • Lead (predom motor)
Immune-mediated /inflammatory conditions: • acute onset- GBS (predom motor) • chronic inflammatory demyelinating polyneuropathy (CIDP) • Lambert-eaton / Myasthenia Gravis • rheumatoid arthritis • Sjogren's • SLE • sarcoidosis • ANCA positive vasculitis
Paraneoplastic causes,
• Solid organ malignancy such as lung cancer
• or paraproteinemia
Genetic
• Charcot marie tooth (predom motor)
Electrophysiology in peripheral neuropathy
Nerve conduction studies can distinguish between axonal and demyelinating causes
and if length-dependent
axonal vs demyelinating causes of peripheral neuropathy
distinguish with nerve conduction studies
Axon loss
• trauma / toxic / ischemic / metabolic / genetic conditions
Demyelination
• compressive neurop
• hereditary neurop
• acquired immune-mediated e.g. GBS and CIDP
Interpretation of Romberg’s test
If ataxic and Romberg positive- implies ataxia is sensory in nature (i.e. from loss of proprioception)
If ataxic and Romberg’s not positive- implies ataxia is due to cerebellar dysfunction
Next steps of investigation for peripheral neuropathy
- Bedside tests for diabetes: CBG, urine dipsticks
- Diabetic retinopathy w fundoscopy
- Basic blood tests including antibodies
- Nerve conduction studies
Features of charcot marie tooth
Generalised wasting, particularly distal - inverted champagne bottle
Weakness - high stepped gait/ foot drop
Reduced sensation
Is charcot marie tooth demylinating?
There are many types, some demylinating and some axonal
Type 1 is associated with demyelination
Inheritance of charcot marie tooth
Can be auto dom, recessive or X-linked
Most common is Type 1 which is auto dom
Causes of third nerve palsy
Congenital vs Acquired
Acquired
- Vascular ischemia (commonly diabetes, hypertension)
- Vasc abnormality like aneurysm (esp in PKD)
- SOL
- Inflammation / infection
- Demylinating - MS
- Post-op
- Cavernous sinus thrombosis
Ophthalmoplegic migraine
third nerve palsy signs
- Ptosis (paralysis of levator palpebrae superioris muscle)
- “Down and out” occular deviation
- Pupil becomes fixed and dilated/mydriasis (paralysis of sphincter pupillae)
- Diplopia
Drug triggers for Myasthenia Gravis
Aminoglycosides - Gent, Neomycin Beta blockers Cipro D-penicillamine (for Wilson's) Fluoroquinolones - cipro , Levo Quinine Magnesium Statin
Lambert Eaton Vs myasthenia gravis
In LES:
• rare to have opthalmeplegia
• rare to have severe repiratory muscle weakness
- but has autonomic dysfunction: dry mouth /metallic taste, constipation, and erectile dysfunction
- Fatigue IMPROVES with exercise in LE
- LEMS voltage gated calcium channel
- MG AChR
Features of myotonic dystrophy
Most common adult onset muscular dystrophy
Auto Dom, shows anticipation
CTG repeat mutation
Frontal balding Cataracts Bilat ptosis Facial weakness Testicular atrophy Arrythmia Reduced IQ
Differential of bilat ptosis
- MG
- Muscular dystrophies (Myotonic, Occulopharyngeal)
- Chronic progressive external opthalmeplegia
- Congenital
- Bilat Horner’s
- Syringomyelia
Arm dermatomes
C5 - lat upper arm
C6 - lat lower
C6 specifically median nerve - Lat (thumb) edge of hand
C7 - middle finger
C8 specifically ulnar nerve - medial edge (little finger)
C8 - medial lower arm
T1 - medial upper arm
Jaw jerk reflex
Tests CN V - trigeminal
When abnormal, with upper motor neuron lesions, there is a hyperactive or repeating reflex
(past test says you don’t feel anything normally)
CN for facial expression
CN 7 - facial
can test strength too, by attempting to pull apart
cough reflex
starts with stimulation of irritant receptors with afferents in the vagus nerve (CN X)
Specific sign of ALS
first dorsal interosseous muscle wasting ( thenar eminence ) compared to the hypothenar
AKA split hand sign
MND with only lower motor neuron signs
Spinal muscular atrophy (SMA) - autosomal recessive
Kennedy disease - X-linked recessive
Motor neuropathy with conduction block - acquired and treatable
What is the difference between fasciculation and fibrillation?
Both can be picked up on EMGs
Fibrillations are action potentials of individual fibres
Fasciculation is the summation of them all.. and are VISIBLE
signs and symps of MND
Rapid and aggressive asymmetrical disease process involving upper and lower motor neurons
May have behavioral / cognitive dysfunction frontotemporal dementia
three key features of MND
Weakness
Fasciluations
Wasting
Management of MND
Full mdt, dietician, SALT, specialist nurse, resp function monitoring
NIV, gastrostomy
Riluzole has small effect in prolonging survival
What treatment for MND extends life longest?
NIV extends 7 m
Riluzole extends 3m
Claw feet and motor sensory neuropathy
Charcot Marie tooth
Syncope differentials
Vasovagal
• Postural hypotension
• Micturition syncope
• Anxiety
Cardiac
• Arrhythmia
• AS
• HOCM
Respiratory
• PE
Neurological • Seizures (?TS etc) • TIA / stroke • Lack of sleep • Autonomic dysfunction (DM / Parkinson’s / MSA) • ICH / SOL • Meningitis etc
Drugs
• Alcohol
• Withdrawal / OD
Endocrine • Hypoglycaemia • Diabetic autonomic neuropathy • Addison’s • Electrolyte disturbance
Eye examination in Parkinson’s
Myerson’s sign / glabellar tap sign - tap between eyebrows and unable to resist blinking - early sign
Nystagmus - multisystem atrophy
Vertical gaze palsy (especially downgaze) - progressive supranuclear palsy
causes of cerebellar dysfunction
- MS or MSA
- Alcohol (and other drugs)
- Vascular - Posterior circulation stroke
- Inherited (ataxic telangiectasia, Friedreich’s ataxia) Inflammatory (Miller Fisher), Infectious (HIV, syphilis, CJD)
- SOL
Syncope twitch Vs seizures
Syncope fall flaccid, random twitching, rapid recovery
Seizures tend to be rigid and more repetitive movement
Incontinence isn’t a great differentiator
Tongue biting particularly side or back are indicative
Red flags of syncope-
unprovoked or during exercise
murmur
family history
Key features of Myasthenia gravis history
Fatigability
Ptosis that gets worse during the day
Intermittent double vision , or changes -and DRIVING
Chewing getting worse by end of meal
Head drop
Brushing/washing hair etc
Co existing autoimmune
Criteria indicating potential myasthenic crisis
- FVC < 20 or progressive decline
- Can’t complete sentences
- Can’t control their own secretions
- Can’t lift head off pillow
….all require ICU assessment early
What can worsen myasthenia gravis?
Drugs gent,
BASIC LM in caution
Beta blockers Aminoglycosides - Gent, Neomycin Statins Iodine Calcium channel blockers Lithium Mg
epilepsy advice for patients
- Don’t take baths,
- If you swim, go with someone else
- Don’t use heavy machinery
- Pregnancy and medications
- Driving - 6 months if normal EEG, or 12m, or 5 years if HGV driver
- Offer support from Epilepsy Society, specialist nurses and Letter for employer
spasticity vs rigidity
both increased tone, but spasticity is velocity-dependent
What are the functions of the facial nerve
“face, ear, taste, tear”
Causes of Bell’s Palsy
Likely related to HSV
More likely in pregnancy, diabetes