EM Neuro Flashcards
What’s the most sensitive NCS?
Sensory NCS, on the sural nerve
On EMG, fibrillation potential, or positive sharp waves, are a clear sign of?
Denervation
On EMG, prolonged, polyphasic, increased amplitude of motor units = ?
Neuropathic process. Prolonged amplitude, because there are more muscle fibres than usual firing off (muscle units belonging to dead nerves get recruited by living ones). Polyphasic, because recruited muscle fibres lie outside the main area of the motor unit.
EMG with brief, low amplitude units, and early interference pattern = ?
Myopathic process. Disease which randomly knocks off muscle fibres.
If you see fibrillations (clinically) & sharp waves on EMG, you should think..?
ALWAYS think neuropathy (at least for BPT exam!)
Ramsay Hunt syndrome caused by? Bell’s?
HZV (aka VZV).
T/F? There’s evidence that antivirals within 72 hrs of Ramsay Hunt Syndrome developing will improve progonosis
True
T/F? R) MCA infarct (posterior division) can cause neglect
True, often in multiple areas, eg auditory, sensory, visuospatial. eg) pt fails intersecting pentagons on MMSE, difficulty putting on jacket, crowds all the numbers on the R) side of the clock face
How do you diagnose a small fibre neuropathy?
Skin biopsy - see destruction of small epidermal nerves.
What cells are causing MS? what do they secrete?
Th1 cells, secrete IFN-gamma. (NB: IFN-alpha is treatment for MS)
The most common cause of epilepsy in those > 65 yrs is?
Previous strokes
In paraneoplastic disorders, would ataxia be seen unilateral or bilateral (symmetrically)?
Symmetrical
Where would you expect to see brain mets?
Lodged between grey-white interface, where the vessels are the narrowest. However, brain mets can be anywhere.
What nerve involvement in VZV would mimic a presentation of meningitis?
Greater occipital nerve - goes in a path that when irritated can cause neck stiffness
Pt p/w ataxia, confusion, ophthalmoplegia, lateral gaze difficulty. Diagnosis?
Alcohol related nerve injury - treat with thiamine. Pts often have residual deficit - amnestic MCI.
Wernicke’s encephalopathy carries what mortality rate?
1-2%. This condition is potentially reversible with thiamine
A pt with NHL p/w multiple nerve root involves (including CN 6 palsy, weakness in L5 distribution, diplopia, bladder disturbance, leg weakness, reduced / a/reflexia). Dx?
Lymphoma recurrence - multiple meningeal disease
With regards to postherpetic neuralgia, if simple analgesics (paracetamol, NSAIDs) fail, what is the next line of management?
Gabapentin (pregabalin similar efficacy; if one doesn’t work though, try the other, sometimes a person will get a response). NNT = 3.
Name two indications for pregabalin (or gabapentin)?
Postherpetic neuralgic treatment (NNT = 3), DM neuropathy
What is the biggest risk factor for chronicity of postherpetic neuralgia?
Increasing age
What’s the most appropriate first-line AED for JME?
Valproate. Change to lamotrigine if pre-pregnancy.
Which investigation best provides diagnosis for narcolepsy?
Mean sleep latency test
The following are classic symptoms of what? Excessive daytime sleepiness, catalpesy, hyponogogic hallucinations
Narcolepsy
What is a ‘positive’ (or ‘abnormal’) result in the mean sleep latency test?
Time for someone to fall asleep is
What’s the treatment of narcolepsy?
Retanil - dexamphetamine
T/F? With regards to MS, PML has no mass effect and does not enhance on MRI brain
True. It’s black on T1, white on T2, involves subcortical U-fibres, and is multifocal.
What’s the baseline risk of PML for those with MS on natalizumab?
1 in 1000
What is wrong in PML?
PML is oligodendrocyte infection from JCV
What sort of vision do you get with an optic chiasm defect? How about an optic tract lesion? Posterior circulation stroke?
Optic chiasm - get tunnel vision
What causes myasthenia gravis?
Acetylcholine antibodies
You see a decremental response on NCS in what condition?
Myasthenia gravis - every stimulus uses up some ACh until there’s none left
EEG 3 Hz generalised spike wave = ?
Childhood absence seizures
EEG focal spike wave activity = ?
Local epileptogenic activity, eg tumour, abscess
EEG triphasic waves = ?
Metabolic encephalopathy (probably liver)
Periodic sharp waves = ?
CJD
A Parkinson’s picture and impaired downward saccades =
PSP
List the DDx for Parkinson features & symmetrical presentation, vs Parkinson features & asymmetrical presentation
Asymmetric = PD, corticobasal degeneration
Gentamicin ototoxicity causes ‘imbalance’, not ‘vertigo’
Fact.
If someone is unconscious with symmetrical signs, you should worry about metabolic disturbance
A vascular event tends to be asymmetrical
Mixed UMN & LMN defect = ?
MND
With regards to MS, beta-interferon reduces future attacks by what %?
30%
How does natalizumab work? How much % does it reduce MS attacks?
Alfa-integrin antibody - stops T cells getting into CNS. 80% reduction in MS attacks.
Pyramidal’ = ?
UMN
When does chemotherapy-associated neuropathy present?
Around the time chemo is given, not usually delayed presentation
Biceps jerk innervated by?
C5 > C6, Musculocutaneous nerve
Brachioradialis jerk innervated by?
C6 > C7, Radial Nerve
Triceps jerk innervated by?
C7, Radial nerve
Finger jerk innervated by?
C7, 8, Median & ulnar nerves
Knee jerk innervated by?
L3, L4, femoral nerve
Ankle jerk innervated by?
S1, posterior tibial (branch of sciatic nerve)
Plantar reflex innervated by?
UMN
Deltoid innervated by?
C5, auxillary
Infaspinatus innervated by?
C5, suprascapular nerve
Post-viral inflammatory brachial plexopathy?
Motor weakness in (can be single) nerve roots, a/w pain, occurs post viral infection.
Commonest cause of wasted first interossei
Ulnar nerve
Weak flexors / forearm muscles
Inclusion body myositis
DDx L5 vs common peroneal nerve lesion
Plantar flexion - S1, some S2, posterior tibial.
Knee extension innervated by?
L3, L4, femoral nerve
Knee flexion innervated by?
L4, L5, S1, S2, branches of sciatic nerve, mostly tibial nerve, some peroneal involvement
Hip flexion innervated by?
S2, 3, nerve to iliopsoas
Hip extension innervated by?
Gluteal nerves, L5, S1, S2
Hip adduction innervated by?
L2, L3, obturator nerve
Hip abduction innervated by?
Mainly L5 involvement
Oscillopathy - trouble tracking motions. Due to a problem with what nerve?
Vestibular nerve. Can be how gentamicin toxicity presents
