Weakness
see also floppy infant
1) Weakness OR Asthenia
2) Localise lesion in motor pathway
3) Determine cause
Weakness = reduced power
V functional limitation but not reduced power i.e. not weak
GRADE POWER
Localise
deep tendon reflexes, Babinski sign up in UMN, down in LMN
Generalised: NMJ / cachexia/late motor neurone
Proximal: myopathy inc dystrophies
Distal: neuropathy / early motor neurone
NB Myasthenia gravis (a NMJ) can present in any pattern
sensory in all but pattern can help localise
Nerve conduction: differentiates
Neurological Dx
1) Weakness OR Asthenia
2) Localise lesion in motor pathway
3) Determine cause
Weakness = reduced power
V functional limitation but not reduced power i.e. not weak
- Musculoskeletal
- asthenia = power impaired by pain or joint dysfunction, but normal power
- joint disease: joint pain ?arthritis
- muscle disease: myalgia (not typical of myopathy) ?myositis, rhabdo, cramps, polymyalgia rheumatica, fibromyalgia
- NB some myopathies do present with pain e.g.
- infectious myopathies such as trichinellosis and viral myositis
- certain drug-induced myopathies
- thyroid myopathy
- inherited metabolic myopathies
- asthenia = power impaired by pain or joint dysfunction, but normal power
- Neurological
- paresthesias
- spasticity impairing power
- fatigue
- cardiopulmonary disease, anemia: shortness of breath, chest pain, poor exercise tolerance
- cachexia from
- malignancy (muscle wasting but normal power)
- chronic infectious or inflammatory disease
- depression
GRADE POWER
Localise
- UMN
- motor cortex
- corticospinal tracts
- LMN
- anterior horn cells
- spinal nerve roots
- peripheral nerves
- neuromuscular junction
- muscle
deep tendon reflexes, Babinski sign up in UMN, down in LMN
Generalised: NMJ / cachexia/late motor neurone
Proximal: myopathy inc dystrophies
Distal: neuropathy / early motor neurone
NB Myasthenia gravis (a NMJ) can present in any pattern
sensory in all but pattern can help localise
- dermatomal
- glove and stocking: neuropathy
Nerve conduction: differentiates
- axonal degeneration
- demyelination
- conduction block
- neuropathy (should be no activity at rest)
- Myopathy
- Myopathies
Neurological Dx