Weakness may be due to a number of conditions.
Upper motor neuron:
(1) stroke
(2) intracranial space-occupying lesion
Upper motor neuron, spinal cord:
(1) transverse myelitis
(2) spinal cord infarct
(3) epidural or subdural hemorrhage
(4) intervertebral disc herniation with cord compression
(5) tumor
(6) multiple sclerosis
Lower motor neuron:
(1) amyotrophic lateral sclerosis
(2) poliomyelitis
(3) intervertebral disc herniation with compression of spinal nerve root
(4) Guillain-Barre syndrome
(5) ciguatera poisoning
(6) tetrodotoxin poisoning
(7) paralytic shellfish poisoning
(8) porphyria
(9) heavy metal poisoning (lead, other)
(10) alcohol or drug-related
(11) diabetes
(12) plexopathy
(13) peripheral nerve compression
Neuromuscular junction disorder:
(1) myasthenia gravis
(2) Lambert-Eaton myasthenic syndrome
(3) botulism
(4) tick paralysis
(5) organophosphate poisoning
Myopathy:
(1) polymyositis
(2) electrolyte-induced
(3) alcohol or drug-induced
(4) muscular dystrophy
(5) endocrinopathy
Other:
(1) conversion disorder
(2) malingering
(3) chronic fatigue syndrome
(4) anxiety disorder
(5) fibromyalgia
