UPPER MOTOR UNIT DISORDERS LOWER MOTOR UNIT DISORDERS Cerebral cortex Anterior horn cell Cerebrovascular infarction Poliomyelitis Cerebrovascular hemorrhage Postasthmatic amyotrophy Ruptured arteriovenous Spinal muscular atrophy malformation Amyotrophic lateral sclerosis Ruptured aneurysm Peripheral nerve Brain tumor hemorrhage Guillain–Barré syndrome Cerebral embolism Erb/Klumpke palsy Transient ischemic attack Heavy metal poisoning Todd postictal paralysis Pharmacologic medicines Amyotrophic lateral sclerosis Marine toxins Spinal cord Acute intermittent porphyria Trauma Neuromuscular junction Cord concussion Botulism Epidural hematoma Myasthenia gravis Fracture Tick paralysis Dislocation Organophosphates Transection Neuromuscular blockers Epidural abscess Snake envenomations Discitis Muscle Spinal cord tumor Muscular dystrophy Transverse myelitis Myotonic dystrophy Anatomic Dermatomyositis Atlantoaxial dislocations Chiari malformations Infectious Tethered spinal cord Pyomyositis Viral myositis Amyotrophic lateral sclerosis Trichinosis Acute flaccid myelitis Metabolic abnormalities Miscellaneous disorders Periodic paralysis Congenital hypothyroidism Rhabdomyolysis/myoglobinuria Benign congenital hypotonia Inborn errors of metabolism Alternating hemiplegia Endocrine disorders Acute hemiplegic migraine