Muscle weakness Flashcards
What is the movement pathway?
Motor cortex Medulla/spinal cord Anterior horn Motor neurone Neuromuscular junction Muscle
What can affect the motor cortex?
Stroke, tumour, MS
What can affect the medulla/SC?
Stroke, tumour, MS
What can affect the anterior horn?
MND
What can affect the motor neurone?
MND, neuropathy
What can affect the NMJ?
Myasthenia Gravis
What can affect the muscle?
Myopathy
If their are bulbar sx what is this suggestive of?
MND, MG
If there are opthalmoplegia?
MG, mitochondrial
If there is facial involvement?
MG
If there is fatigue-ability?
NMJ
If there is relapse remission
inflammatory
if it is fixed?
Stroke
Describe peripheral neuropathy
Chronic and slowly progressive
Starts in the legs and longer nerves (length dependent)
Weakness, numbness, LMN
Commonest cause of a peripheral neuropathy?
Diabetes
Other causes of peripheral neuropathy?
Vitamin deficiency e.g. B12 /Folate Toxins: - Alcohol - Chemotherapy - Amiodarone - Lead - Aluminium Metabolic disorders: - Thyroid, uraemia HIV Paraneoplastic Syndromes Hereditary neuropathies: - Charcot Marie Tooth/ Hereditary sensory and motor neuropathy - Hereditary liability to pressure palsies
Causes of mononeuritis multiplex
vasculitides
connective tissue disorders - sarcoid
Causes of mononeuropathy
Median nerve entrapment at the wrist most common ( Carpal Tunnel Syndrome)
Ulnar nerve at elbow common (handlebar palsy)
Radial nerve in axilla common (wrist drop)
Common peroneal nerve in leg
Investigations for a neuropathy
History and examination \+/-Neuropathy screen \+/-Vasculitic screen \+/-EMG/NCS \+/-CSF study \+/-nerve biopsy
Bloods for neuropathy screen
FBC ESR U+E, glucose, TFT, CRP, Serum electorophoresis B12 Folate Anti Gliadin (TPHA, HIV)
Bloods for a vasculitic screen
FBC, ESR
U+ECr, CRP
ANA, ENA, ANCA, anti dsDNA, RhF, Complement, Cryoglobulins
Tx for neuropathies
20% no tx (neuropathic analgesia e.g. gabapentin, pregablin)
Treat/remove underlying cause e.g. gluten, sugar
Steroids in inflammatory
Myasthenia gravis cause
NMJ, antibodies attack the Ach binding sites therefore no muscle activation
Other sx of MG
THYMUS DYSFUNCTION
- *fatigueable weakness:
- Neck and face (head drop, ptosis)
- extraoccular (complex diplopia)
- Bulbar (speech, swallow) particularly elderly
- Breathing
MG ix
AChR antibodies EMG Repetitve stimulation looks at NMJ CT thorax Tensilon test
MG treatment
Acetylcholine esterase inhibitors (pyridostigmine) – symptomatic
Immunosuppresants
Steroids (start slowly)
Azathioprine/Methotrexate/mycophenolate
Thymectomy
Monitor FORCED VITAL CAPACITY and bulbar function
What is a myasthenic crisis?
- severe weakness including resp and bulbar muscles
- high risk of death
- urgent review by neurologists and anaesthetic review
Uncommon muscle disorders
Most genenetic muscular dystrophies - Duchenne, Becker, FSH, LGD Inflammatory muscle disease - Polymyositis, Dermatomyositis Mitochondrial disorders
Muscle investigation
CK
EMG
ESR/CRP
+/-Genetics (DMD/Becker)
+/-biopsy
Muscle disorder treatment
Remove causal agent Supportive: MDT - OT (aids adaptations) - Physio (prevent contracture) - Back - Renal - Diet Immunosuppress if inflammatory Steroids/gene therapies
