In station 5 you may be asked to assess a patient with eyelid drooping, double vision, weakness etc.
History (3 minutes):
- Timing questions: symptoms since when, sudden/gradual onset, intermittent/constant symptoms, getting worse, worse at the end of the day?
- Eyelid drooping
- Double vision: is this worse at the end of the day
- Speech disturbance
- Difficulty swallowing
- Weakness of face muscles and limbs. Is this fatiguable?
- Shortness of breath
- Triggers of myaesthenic crisis: infection, drugs (recent antibiotics, beta-blockers, calcium channel blockers
- Consider Myotonic dystrophy: balding, cataracts, heart problems, lung problems, gut problems, diabetes, excessive daytime sleepiness
- Neuro Questions: sensory loss, headache, seizures, tremor, unsteadiness, etc.
- Consider Horner’s syndrome: cough, haemoptysis, chest pain, smoking history, weight loss (Pancoasts tumour causing Horner’s syndrome), loss of sweating on face/arms/trunk, any trauma/surgery on neck, any pain in neck, any headache.
- PMH: autoimmune conditions, CVS risk factors
- Dx: including penicillamine
- Fx: autoimmune, weakness eg. myotonic dystrophy
Examine (3 minutes):
If suspect ptosis proceed as follows:
- Inspect: ptosis (uni/bilateral, symmetrical/asymmetrical, partial/complete),eye position, pupils (size: big in CN III palsy, small in Horners, normal in myasthenia/myotonic dystrophy/CN III palsy)
- Eye movements and ask if gets double vision (observe for [complex] opthalmoplegia) and fatiguability on looking up for 20 seconds (myasthenia). Make a point of testing CN 4 (ask to look down and in) and CN 6 (ask to look laterally)
- Pupils: reflexes, RAPD
- Visual fields
- Temporal arteries palpation (if age >50)
- Visual acuity
- CNs V, VII, VIII, IX, X, XI, XII
- Quick neuro assessment: tone, power, sensation (sensation is normal in myasthenia and myotonic dystrophy), reflexes (reduced/absent in myotonic dystrophy), coordination
- Extra myasthenia tests:
- Test eye closure (peek sign) and test lip closure
- Neck flexion and extension against resistance. Jaw supporting sign.
- Test power of elbow flexion/extension, shoulder abduction. Ask to do ‘chicken wing arm exercises 10-20 times’ then retest power (weaker after exercise).
- Test speech (count to 50) ?fatiguability
- Look for a sternotomy scar (thymectomy), spirometer, gastrostomy/NG tube, does the patient appear cushingoid
- Resp: chest expansion and offer to do FVC
- Don’t miss evidence of other autoimmune conditions e.g. thyroid, RA, SLE, diabetes
- Extra tests for myotonic dystrophy:
- Shake patient’s hand (delay before grip release), ask to repeatedly open and close fist
- Percussion myotonia (use tendon hammer to tap thenar eminence, the thumb flexes)
- Pulse check, look for diabetic fingerpick marks
- Face and neck: frontal balding, myopathic facies, cataracts, palpate temporalis and masseter when patient clenches teeth (wasted and weak), palpate sternocleidomastoid (wasted and weak) and observe/palpate for a goitre. Ask to close eyes tightly then open (delayed eye opening)
- Chest: gynaecomastia, apex beat, PPM scar, auscultate heart sounds (murmur), auscultate lungs (bronchiectasis)
- Abdomen: eg. for PEG
- If suspect Horner’s:
- Examine the hands for wasting, APB power, FDI power, sensation C8-T1, clubbing, DM fingerprick marks
- Neck-scars, carotid pulse, palpate for LNs, goitre, trachea position, auscultate for carotid bruits
- Chest- auscultate heart and lungs
- Axilla- scars
ICE+ Explanation (2 minutes)
A suggested explanation is as follows:
“There are lots of causes for double vision/eyelid drooping. It can be a problem with the eye muscles. I think you might have myasthenia gravis. In this condition the muscles become weak and tired. The muscles around the eyes are commonly affected causing double vision and eyelid drooping which is worse at the end of the day. It is caused by a problem with the immune system. It can also affect the face and neck muscles and cause problems with swallowing, speech and breathing. Some people have weak arms and legs too. Sometimes infections or medications can trigger the symptoms to get worse. I’m going to arrange for you to have some blood tests and nerve and muscle tests, a CXR and some breathing tests. I’ll ask a specialist in neurology to come and see you. If it is myasthenia gravis, treatments are available.
Present to the examiner:
“I think this patient has myasthenia gravis as evidenced by muscle weakness with fatiguability. There is bilateral assymetrical fatiguable partial ptosis. There is diplopia and complex opthalmoplegia. There is bilateral facial muscle weakness with weak eye closure, lip seal and peek sign is positive. There is weakness of neck extension and jaw supporting sign is positive. There is proximal limb weakness which is fatiguable. There is dysarthria and dysphonia. I observed a midline sternotomy scar and signs of steroid toxicity. Chest wall expansion was reduced. I looked for evidence of other autoimmune disorders”
Differential Diagnosis of ptosis:
- Myasthenia Gravis (bilateral)
- Myotonic dystrophy (bilateral)
- Horner’s syndrome
- 3rd CN palsy
- Oculopharyngeal muscular dystrophy (bilateral)
- Mitochondrial disease e.g. Kearns-Sayres (bilateral)
Differential Diagnosis of complex opthalmoplegia:
- 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 variant of Guillain barre syndrome
- Cavernous sinus pathology
- Wernickes encephalopathy
- Progressive supranuclear palsy
Differential diagnosis of myasthenia gravis in general:
- LEMS (lambert eaton myaesthenic syndrome): antibodies to presynaptic voltage gated calcium channels. Associated with cancer. No opthalmoplegia. No bulbar involvement. No respiratory involvement. Proximal muscle weakness improves with exercise. Reduced/absent reflexes that increase after exercise. Autonomic features. Sensory features.
- Mitochondrial disease e.g. Kearn’s sayres
- Miller fisher variant of guillain barre syndrome
An 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
Bloods: AChR Antibodies (80-90%), antistriatal muscle antibodies (90% with thymoma), anti-MUSK (10-20%, often positive if AChR antibodies negative), TFTs (graves in 5%, exclude thyroid eye disease as cause of opthalmoplegia), FBC+CRP (infection), CK (normal), U+E (low K+)
Diagnostic: tensilon test (edrophonium test – give IV anticholinesterase injection and look for improvement in ptosis within 30 seconds for 2-3 minutes, cardiac monitoring is needed for bradycardia, conduction block and asystole with a resus trolley to hand)/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)
Imaging and respiratory function tests: sats, ABG, spirometry (FVC), CXR, CT/MRI thymus
- Manage precipitant (infection, drugs, noncompliance with medication, low K+)
- NG/PEG feeding
- Anticholinesterases (pyridostigmine)
- Steroids (prednisolone) and gastro and bone protection
- Steroid sparing agents (Azathioprine, mycophenolate)
Myotonic Dystrophy (MD)
MD is the most common adult muscular dystrophy. It is due to expansion of an unstable trinucleotide repeat (CTG) on chromosome 19.
Autosomal dominant. DMPK gene encoding for myotonin protein kinase.
Shows anticipation (worse symptoms and signs in next generations, earlier presentation if increase in repeat length)
Causes abnormally sustained muscle contraction after voluntary contraction ceases. Worsened by cold/emotions/exercise.
Starts in adulthood (20-30 years old)
Frontal balding, cataracts, bilateral ptosis, facial weakness (myopathic facies), wasting of temporalis and masseter, wasted and weak sternocleidomastoids (swan neck), muscle weakness (proximal and distal), grip myotonia, gynaecomastia, cardiomyopathy and arrhythmias, testicular atrophy, diabetes, peripheral neuropathy, oesophageal/biliary tree/bowel involvement (dysphagia, constipation/diarrhoea, reflux), aspiration and bronchiectasis, nodular thyroid, psych problems, mild intellectual impairment, hypersomnia
Differential Diagnosis: fascioscapulohumeral dystrophy (face and neck weakness, ptosis, winged scapula, hypertrophy of deltoids)
EMG- dive bomber pattern, waxing and waning of potentials. Repetitive discharges with minor stimulation.
Muscle biopsy- fibre atrophy type 1, no inflammation
CK- normal/mildly elevated
Associated features: glucose/Hba1c (diabetes), ECG (long PR, long QT, heart block), CXR (cardiomegaly), slit lamp examination (cataracts)
MDT: ophthalmology, gastroenterology, cardiology, respiratory, endocrinology, neurology, SALT, physio, OT, GP, psychiatry, geneticist
Medical: phenytoin/ quinine/ procainamide/ mexiletine for myotonia
Manage complications eg. pacemaker for heart block, diabetes, obstructive sleep apnoea
Surgical: anaesthesia is high risk, cataract removal
Third CN palsy
- Complete (compressive cause)/partial ptosis (medical cause) of single eyelid (paralysis of LPS muscle)
- Dilated pupil not reactive to direct/consensual light/accommodation (lose parasym supply to pupil)
- Eye abducted and depressed (unopposed LR6, SO4)
- Diplopia in all directions
- Difficulty with medial and superior gaze
Causes of CN III lesion:
- Midbrain stroke/SOL/demyelination (may have hemiparesis, cerebellar signs, INO, RAPD)
- Posterior communicating artery aneurysm
- Cavernous sinus pathology- thrombosis, internal carotid artery aneurysm, pituitary tumour etc. (may have associated CN abnormalities IV, Va, VI)
- Supraorbital fissure pathology eg. tumour, thyroid eye disease, fracture (may have associated CN abnormalities IV, Va, VI)
- Orbital mass/inflammation/cellulitis
- Herniation of uncus through tentorium (false localising sign)
- Other: 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
Differential Diagnosis of dilated pupil: Holmes Adie, mydriatic eye drops, tricyclic antidepressants, amphetamines, phaeochromocytmoa, congenital.
If compressive (pupil dilated)/brainstem signs/other CNs involved/acute and sudden headache: urgent MRI/MRA/CTA +/- treat the cause eg. neurosurgery referral for coiling/clipping an aneurysm.
If pupil spared and isolated CN 3 palsy with complete external dysfunction and patient is old with vascular risk factors: check BP, glucose, lipids, FBC, ESR/CRP/PV, TFTs, HIV and observe. MRI brain if no cardiovascular risk factors at presentation. Optimise cardiovascular risk factors. No driving, climbing, heavy machinery. Eye patch/prism for diplopia. Review at 3 months. If not recovered, perform MRI head. Note: some clinicians feel that it is safest to image all CN 3 palsies regardless of pupil involvement, pain, age, presence of CVS risk factors.
- Partial ptosis of single eyelid
- Miosis of pupil with intact light reflex and accommodation
|Central- hypothalamus, brainstem and cervical cord||Preganglionic- superior mediastinum||Postganglionic- neck|
|Loss of sweating (face, arm, trunk)||Loss of sweating on face||No Loss|
NB: likely other neurological signs
|Trauma to brachial plexus
Neurofibroma at T1
Cervical lymph nodes
Cavernous sinus thrombosis
Trauma/surgery to neck
|MRI brain and spine||CXR, CT Thorax, lymph node biopsy||MRI/A head and neck
MRI cavernous sinus and orbits
Pancoast’s tumour: wasting of ipsilateral hand muscles, T1 (+/- C7-8) sensory loss, clubbing, tracheal deviation, lymph nodes, ipsilateral chest signs.
Differential Diagnosis of small pupil: Argyll-Robertson pupil (syphilis), opiates, pilocarpine drops
To confirm diagnosis of Horner’s syndrome:
- Cocaine 4%- normal pupil dilates, no dilatation at 60 minutes of affected pupil
- Apraclonidine 0.5%- miosis of normal pupil, relative mydriasis of affected pupil due to denervation hypersensitivity
- Hydroxyamphetamine 1%- NA is released from postganglionic neuron causing pupil to dilate if central/preganglionic cause but not if postganglionic cause
Management: treat the cause.
Written by Dr Sarah Kennedy
Resources used to write this document include those listed in the resources section of this webpage.