Neurology Flashcards
Causes of a 6th nerve (abducens) palsy?
Causes of mononeuritis multiplex
Vascular lesion
Malignancy
Demyelination
Infection (Lyme disease, syphilis)
Raised IC pressure (false localising sign)
Wernicke’s encephalopathy (if bilateral)
Causes of mononeuritis multiplex? WARDS PLC
Wegener’s granulomatosis
Amyloidosis
Rheumatoid arthritis
Diabetes mellitus
Sarcoidosis
Polyarteritis nodosa
Leprosy
Cancer
Define and give causes of an internuclear ophthalmoplegia?
INO is a disorder of conjugate gaze, where the eye ipsilateral to the lesion will fail to adduct, and the contralateral eye will exhibit nystagmus. It is caused by a lesion of the median longitudinal fasciculus (MLF).
Causes of an INO include:
Vascular lesion and MS.
Clinical findings of a 3rd (oculomotor) nerve palsy?
Ptosis
Eye ‘down and out’
Pupil may be unreactive + dilated depending on cause
Clinical findings of a 4th (trochlear) nerve palsy?
Weakness of downward movement of the eye, causing vertical diplopia
Clinical findings of a 6th (abducens) nerve palsy?
Cannot abduct affected eye
Causes of a complex ophthalmoplegia?
Nerve lesions: mononeuritis, demyelination
Myasthenia gravis
Graves’ disease
Mitochondrial diseases
Surgical causes of a 3rd nerve palsy?
SURGICAL causes affect the pupil (dilated and unreactive).
Posterior communicating artery aneurysm.
SOL.
ICH.
Medical causes of a 3rd nerve palsy?
MEDICAL causes do not affect the pupil.
Causes of mononeuritis multiplex.
Demyelination (MS).
Infarction.
Investigations in an ocular palsy?
MRI of brainstem and posterior fossa
Investigations for causes of mononeuritis multiplex
Investigations for myasthenia gravis and thyroid disease
Bamford classification of a TACS (total anterior circulation stroke)
Hemiplegia (contralateral to lesion)
Homonymous hemianopia (contralateral to lesion)
Higher cortical dysfunction (dysphasia, dyspraxia, neglect)
Bamford classification of a PACS (partial anterior circulation stroke)
2/3 of TACS criteria
Bamford classification of a LACS (lacunar stroke)
Pure hemi-motor or sensory loss
What is the NIHSS?
The NIHSS is a stroke severity scale, a systematic assessment to measure the neurological deficits seen with acute stroke.
Designed to standardise and document an easy to perform, reliable and valid neurological assessment.
Can be used to determine eligibility for thrombectomy, and to assess treatment success. Can be used before and after thrombolysis or thrombectomy.
How would you assess speech in a patient you suspect has had a stroke?
Give simple, then 2-step commands.
Ask to repeat phrases ‘42 West Register Street’.
Test naming objects: hold up and ask them to name what you’re holding.
What is used to consider eligibility for thrombectomy?
Patient’s overall clinical status
NIHSS (score >5)
Modified Rankin Scale (score >3)
Territories of infarction on brain imaging
How is a POCS (posterior circulation stroke) defined? cerebellum + brainstem
Need ONE of:
Cranial nerve palsy + contralateral motor or sensory deficit.
Bilateral motor / sensory deficit.
Gaze palsy.
Cerebellar dysfunction.
Isolated homonymous hemianopia.
Investigations and management of suspected acute stroke?
Bedside: A-E assessment, observations, GCS, blood glucose (stroke mimics), ECG (AF), urine dip (infection). Obtain collateral history to determine sx onset for thrombolysis eligibility.
Bloods: FBC, CRP/ESR (young stroke - arteritis), UE, TFTs, cholesterol / lipid profile.
Imaging: CT head to rule out haemorrhage. MR brain.
Acute management is either thrombolytic or endovascular:
- Thrombolysis with alteplase (tPA) if <4.5 of sx onset and no ICH.
- If outside thrombolysis window, consider whether eligible for thrombectomy (6-12h sx onset)
- If not eligible, give aspirin 300mg OD for 2 weeks then 75mg clopidogrel lifelong
Longer-term management:
- Consider: echo, carotid doppler, CT venogram (to rule out CVST in young pt), clotting screen (thrombophilia), vasculitis screen (young stroke).
- Referral to HASU
- MDT input: SLT, PT, OT, dietetics (consider NG feeding)
- Secondary prevention: statin, HTN management, smoking cessation, consider anticoagulation if AF
- DVT prophylaxis with IPCs
Differential diagnosis for hemiparesis?
Anterior circulation vascular event affecting R or L cortex or lacunar infarct.
SOL (tumour, SDH, abscess).
Hemiplegic cerebral palsy.
Less common: Todd’s paresis following seizure, hemiplegic migraine, stroke mimic (sepsis, hypoglycaemia, demyelination).
Clinical features of a patient with myotonic dystrophy?
Face:
- long, thin, expressionless face
- wasting of facial muscles
- bilateral ptosis + cataracts
- frontal balding
- dysarthria (myotonia of tongue)
Hands:
- grip myotonia (grip my hand and let go)
- percussion myotonia (percuss thenar eminence + watch for thumb flexion)
Chest:
- cardiomyopathy / pacemaker due to brady and tachyarrhythmias
Limbs:
- wasting and weakness of distal muscles
- areflexia
Other features:
- diabetes - look for libre monitor
- testicular atrophy
- dysphagia
Investigations to perform in myotonic dystrophy?
EMG: ‘dive bomber’ action potentials.
Genetic testing.
Muscle biopsy: fibre atrophy type 1.
Management of complications of myotonic dystrophy?
Affected individuals die prematurely due to respiratory complications.
Weakness is a problem without treatment options.
Phenytoin may help myotonia.
Advise against general anaesthetic.
What are the genetics of myotonic dystrophy?
Type 1: expansion of the trinucleotide repeat sequence on chromosome 19.
Type 2: expansion of the tetranucleotide repeat sequence on chromosome 3.
Shows genetic anticipation (worsening severity + earlier age of presentation with successive generations).
Autosomal dominant condition.
Usually presents in 20-40s.
List the different types of muscular dystrophy.
Duchenne’s muscular dystrophy.
Becker’s muscular dystrophy.
Fascioscapulohumeral muscular dystrophy (affects arms + shoulders).
Limb-girdle muscular dystrophy.
Myotonic dystrophy.
Oculopharyngeal muscular dystrophy.