Neurology Flashcards
What are clinical signs in the face of myotonic dystrophy? (6)
Myopathic facies: long, thin, expressionless
Wasting of facial muscles and SCM
Bilateral ptosis
Frontal balding
Dysarthria due to myotonia of tongue/pharynx
Myotonia of eyes
What are clinical signs in the hands of myotonic dystrophy? (4)
Myotonia
Wasting and weakness distally
Areflexia
Percussion myotonia of thenar eminence
What are some systemic associated findings in myotonic dystrophy? (6)
Cataracts
Cardiomyopathy
Brady and tachy arrhythmias - PPM
Diabetes
Testicular atrophy
Dysphagia
What is the underlying genetic pathophysiology of myotonic dystrophy?
Type 1 or 2 depending on genetic defect
DM1: CTG trinucleotide expansion within DPMK gene chromosome 19
DM2: CCTG repeat sequence ZNF9 gene chromosome 3
Shows genetic anticipation in DM1 so presents earlier 20-40s depending on number of repeats
Autosomal dominant
How is a diagnosis of myotonic dystrophy made? (3)
Clinical features
EMG: dive bomber potentials
Genetic testing
What is management of myotonic dystrophy? (12)
Mexiletine may help myotonia (caution with arrhythmia)
Modafanil for sleepiness
Advise against general anaesthetic
PPM/ICD for arrhythmias/cardiomyopthay
SLT for dysphagia +/- PEG
NIV +/- cough assist device
Surveillance for cataracts
Management of diabetes
Laxatives etc for bowels
Physio/ OT for aids
Orthotics
Palliative care input
What are causes of bilateral ptosis? (5)
Myotonic dystrophy
Myasthenia gravis
Congenital
Oculopharyngeal muscular dystrophy
Mitochondrial disease e.g. Kearns-Sayres
What are causes of unilateral ptosis? (4)
Third nerve palsy
Horners syndrome
Posterior Communicating artery aneurysm
Diabetic neuropathy
What are causes of complex ophthalmoplegia? (9)
Myaesthenia gravis
Thyroid eye disease
Myopathies e.g. oculopharyngeal muscular dystrophy
Mononeuritis multiplex eg. diabetes causing multiple CN palsies
Mitochondrial disease e.g. Kearn’s Sayres
Miller fisher syndrome
Cavernous sinus pathology
Wernickes encephalopathy
Progressive supranuclear palsy
What are differentials for myasthenia? (4)
Lambert eaton myaesthenic syndrome: antibodies to presynaptic voltage gated calcium channels
Botulism
Mitochondrial disease e.g. Kearn’s sayres
Miller fisher variant of guillain barre syndrome
What is the pathophysiology of myasthenia gravis?
acquired autoimmune disorder
Antibodies to the postsynaptic AChR of the neuromuscular junction
Thymus is involved in 75% of cases (10-15% have thymoma of which 10% are malignant, 90% have thymic hyperplasia)
50% with thymoma get myasthenia gravis
Occurs in 1 in 10000
20-35 year old females (autoimmune, thymic hyperplasia) or >50 year old men (oculobulbar, thymoma)
Affects extraocular, bulbar, facial, neck, limb and trunk muscles usually in this order
15% have pure ocular MG
20% have pure bulbar
It can be induced by penicillamine
What are investigations of myasthenia gravis? (7)
Bloods: AChR Antibodies, antistriatal muscle antibodies, anti-MUSK, TFTs, FBC+CRP, CK (normal), U+E (low K+)
Tensilon test - IV anticholinesterase injection, look for improvement in ptosis, cardiac monitoring needed for bradycardia, conduction block and asystole
Icepack test (ice is applied to the patients eyelid for 2 minutes causing ptosis to improve in MG).
Nerve conduction studies and EMG: repetitive nerve stimulation test (reduced amplitude with repeated stimulation), single fiber EMG (jitter)
Sats, ABG, spirometry (FVC)
CXR
CT/MRI thymus
What is the management of myasthenia gravis? (8)
Manage precipitant: infection, drugs, noncompliance with medication, low K+
SALT, NG/PEG feeding
Anticholinesterases (pyridostigmine)
Steroids, gastro, bone protection
Steroid sparing agents (Azathioprine, mycophenolate)
Plasmapheresis
IVIG
Surgical: Thymectomy
What are findings of a 3rd nerve palsy? (5)
Complete ptosis: compressive cause
Partial ptosis: medical cause (paralysis of LPS muscle)
Dilated pupil not reactive to direct/consensual light/accommodation (loss of parasympathetic supply)
Eye abducted and depressed (unopposed LR6, SO4)
Diplopia in all directions
Difficulty with medial and superior gaze
What are causes of a 3rd nerve palsy? (9)
Midbrain stroke
SOL
Demyelination
Posterior communicating artery aneurysm (painful)
Cavernous sinus pathology: thrombosis, internal carotid artery aneurysm, pituitary tumour
Supraorbital fissure pathology: tumour, thyroid eye disease, fracture
Orbital mass/inflammation/cellulitis
Herniation of uncus through tentorium (false localising sign)
Medical causes (spare the pupil because the parasym fibres are on the outer surface of the nerve and have their own blood supply from nerve sheath vessels): mononeuritis multiplex eg. diabetes, hypertension, vasculitis, giant cell arteritis, myaesthenia gravis, thyroid eye disease, migraine
What are differentials of a dilated pupil? (7)
3rd nerve palsy
Holmes Adie
Mydriatic eye drops
Tricyclic antidepressants
Amphetamines
phaeochromocytoma
congenital
What are clinical signs of cerebellar syndrome? (11)
Scanning dysarthria /slurred speech
Absence of rebound phenomenon
Finger nose incoordination
Intention tremor
Dysdiadochokinesia
Hypotonia
Hyporeflexia
Nystagmus
Heel shin ataxia
Foot tapping - inability to alternate movements
Wide based gait
What are the clinical finding difference between cerebellar vermis vs lobe lesions?
Vermis: ataxic trunk and gait, normal limbs
Lobe: ipsilateral cerebellar signs in limbs
How does direction nystagmus help identify site of lesion?
Cerebellar: Fast phase towards lesion
Vestibular nucleus/VIII lesion: fast phase away from lesion
What are causes of cerebellar syndrome? (8)
PASTRIES
Paraneoplastic
Alcohol
Sclerosis (MS)
Tumour (posterior fossa)
Rare: friedrichs and ataxia telangectasia
Iatrogenic: phenytoin toxicity
Endocrine: hypothyroidism
Stroke: brainstem
What are possible aetiological clues for causes of cerebellar syndrome on examination? (5)
MS: Internuclear ophthalmoplegia, spasticity, female, younger age, optic atrophy
Friedrichs ataxia: optic atrophy, neuropathy
Bronchial carcinoma: clubbing, tar stained fingers, radiotherapy scar
Alcohol: stigmata of liver disease, unkempt, neuropathy
Phenytoin: gingival hyperplasia
What are signs of MS? (11)
Wheelchair
Ataxic handshake
INO
Optic atrophy
Reduced VA
Cranial nerve palsy
Spasticity in limbs
Upper motor neurone weakness
Brisk reflexes
Altered sensation
Cerebellar signs
What is internuclear ophthalmoplegia?
Medial longitudinal fasciculus lesion
Impaired adduction of the ipsilateral eye with nystagmus of the abducting eye
Eyes can converge normally
What are diagnostic criteria for MS?
McDonald criteria
CNS demyelination causing neurological impairment disseminated in time and space