Condition

Distinguishing features

Guillain-Barré syndromea

History of recent infection; paresthesias; frequently ascending paralysis; early deep areflexia; in advanced disease elevated CSF protein levels; abnormal EMG results

Myasthenia gravis

Recurrent paresis; abnormal EMG results; sustained response to cholinesterase inhibitors

Stroke

Frequently asymmetric paresis; CNS abnormalities observed on neuroimaging studies

Poisoning with substances having neurodepressant effectsb

History of exposure to toxic agents; high levels of drugs or toxins in body fluids

Lambert-Eaton syndrome

Increased muscle strength with prolonged contraction; confirmed small cell lung cancer; EMG results similar to botulism

CNS infectionsc

Altered mental status; CNS abnormalities on neuroimaging studies and EEG; abnormal CSF

CNS tumor

Frequently asymmetric paresis; CNS abnormalities on neuroimaging studies

Inflammatory myopathies

Increased creatine kinase levels

Complications of diabetes mellitus

Sensory neuropathy; paresis involving only few cranial nerves

Hypothyroidism

Abnormal test results

a Including variants of Guillain-Barré syndrome, particularly Miller-Fisher syndrome.

b For instance, acute ethyl alcohol intoxication, poisoning with organic phosphates, carbon monoxide, nerve gas, magnesium.

c Particularly involving the brainstem.