Weakness Flashcards
What associated features should you ask about?
- Blackout, seizures
- Headaches (explore)
- Visual problems
- Balance / hearing / vertigo and dizziness
- Speech and swallowing
- Chest pain and SOB
- Weight loss, appetite change, fever, fatigue, sweats
- Joint pain, back pain, hip pain
- Incontinence, anaesthesia
- Muscle wasting
- Funny sensations, numbness, tingling
What PMH should you specifically enquire about?
Diabetes
Spinal pathology
What medications should you specifically enquire about?
LT corticosteroids
What FHx should you specifically enquire about?
Muscular Dystrophy
Autoimmune disorders
What are the features of Myopathy vs Neuropathy?
Myopathy
- Gradual onset
- Proximal muscles affected
- Selective muscles
- DTR preserved
Neuropathy
- Acute rapid onset
- Numbness and tingling
- Autonomic dysfunction, bladder problems
- Paraesthesia
- Distal weakness
What are the features of Duchenne’s muscular dystrophy?
Presents @ 4 years old
- Problems standing up
- Clumsy walking
- Respiratory failure
CK >40x the normal
What are the features of polymyositis and dermatomyositis?
This is a rheumatological condition
- Slow onset and progressive
- Bilateral Myalgia & Arthralgia
- Dysphagia & Dysphonia
- Fever
What is the treatment for poly/dermatomyositis?
Prednisolone 1mg/kg/day
What is myasthenia gravis?
An autoimmune condition affecting AChR of the postsynaptic membrane at the skeletal muscle, resulting in muscle weakness and fatiguability.
What muscles does myasthenia gravis tend to affect (in order) and what symptoms does this result in?
Extraoccular - Double vision
Levator Palpebrae - Ptosis
Bulbar muscles - Chewing and swallowing
Face and neck muscles - Drooping
What are some associations of myasthenia gravis that you should ask about when taking a history?
Other autoimmune conditions
- Thyrotoxicosis
- Diabetes
- Rheumatoid Arthritis
- Thymoma
What investigations should be carried out for myasthenia gravis?
Tinsilon test: Injection of edrophonium improves strength
Vital capacity
Chest CT or MRI
Antibodies
- AChR receptor antibody present in more than 90%
- MuSK receptor antibody if seronegative
EMG
- Decremental muscle response on repeated stimulation
Plasma thyroxine to rule out associated thyroid disorder
What is the treatment for myasthenia gravis?
Anticholinesterase e.g. Pyridostigmine up to 6x a day
What immunosuppressants may be indicated for myasthenia gravis, and what must be administered on top as prophylaxis?
Prednisolone on alternating days due to side effect of muscle weakness
Give osteoporosis prophylaxis
Can also give azathioprine on top
When may thymectomy be indicated in myasthenia gravis?
If
- Onset <50 years
- Not improved with anticholinesterase
What is the danger in a myasthenia crisis and what is the immediate treatment?
Respiratory depression
Immediate artificial ventilation
Plasma exchange
IV Ig
What is Lambert-Eaton syndrome?
Myasthenic disorder
Can be paraneoplastic, result of small cell lung cancer, or can be autoimmune
NO Bulbar or Extra-occular manifestations…
Therefore SPARES THE EYES
Loss of DTR
Weakness is usually truncal and proximal muscles, especially of the pelvic girdle and thighs.
Weakness and loss of DTR IMPROVES WITH EXERCISE!
EMG is diagnostic.
What is the management of muscular dystrophy?
- Supportive
- Genetic counselling
- Orthosis (brace/splint) and prednisolone may help prolong ambulatory phase
What question should you ask if you suspect infection or encephalitis as a cause of weakness?
Recent overseas travel
What are the key elements in the history of MS?
Visual disturbance in one eye Peculiar sensory phenomenon Fatigue Foot dragging or slapping Leg cramping Urinary frequency Bowel dysfunction 20-40 years old
What are the key findings of examination of MS?
Top to toe
Incorrect response to Ishihara plates, desaturation
Pale optic disc
Abnormal eye movements (Intranuclear ophthalmoplegia)
Spasticity
Increased muscle tone
Increased DTR
Motor weakness and plegia
What are the key findings on investigation of MS?
MRI head - White matter hyperintensities
MRI spinal cord - demyelinating lesions especially C-spine
LP - oligoclonal bands
EP - prolongation of conduction, asymmetrical visual EP
What are the key elements in the history of GBS?
Often there is a PRECEDING VIRAL / BACTERIAL INFECTION
PROGRESSIVE, ASCENDING, SYMMETRICAL muscle WEAKNESS
FLACCID PARALYSIS of LOWER EXTREMITIES before upper extremities
PROXIMAL muscles before distal affected
with
PARAESTHESIA of HANDS and FEET
accompanied by BACK or LEG PAIN
RESPIRATORY DISTRESS if chest involved
What are the key findings on examination in GBS?
AREFLEXIA
OROPHARYNGEAL WEAKNESS
FACIAL WEAKNESS
SPEECH PROBLEMS
OPTHALMOPLEGIA
Dysautonomia (sinus tachy, labile BP, posturoal hypo, urinary retention, ileus)
What are the key findings on investigation in GBS?
LP - PROTEIN IS >1g/L
Spirometry - reduced VC
Nerve conduction studies - PROLONGED DISTAL LATENCIES
What are the key findings on investigation in MG?
Serum Anti-AchR antibody
Anti-MuSK antibody
MG Crisis - Reduced FVC
CT Chest - Thymic enlargement
