Myasthenia gravis (MG) is an autoimmune disorder caused by antibodies directed against the postsynaptic neuromuscular junction of skeletal muscle. MG is characterized by fluctuating weakness that worsens with activity and…
Motor neuron disease refers to a disease process affecting one or both of the two neurons in the motor circuit: (1) the upper motor neurons (UMNs), which originate in the…
The lumbosacral plexus is formed from the L1–S3 nerve roots. It is divided into an upper component (the lumbar plexus), which innervates hip flexion, hip adduction, and knee extension, and…
The brachial plexus is formed from the C5–C8 and T1 nerve roots. It is divided into three trunks: the upper trunk is formed by the junction of the C5 and…
Carpal tunnel syndrome (CTS) refers to symptomatic compression of the median nerve in the wrist as it passes through the carpal tunnel, which is bounded by the carpal bones and…
Mononeuropathy multiplex (sometimes referred to as mononeuritis multiplex) is defined as lesions affecting two or more nerves that cannot be explained by a single root or plexus injury. The involvement…
Neuropathies associated with monoclonal gammopathies (paraproteinemias) are relatively uncommon. Paraprotein subtypes most frequently associated with polyneuropathy include heavy chains (IgM, IgA, and IgG) and light chains (kappa or lambda). Determining…
Nerve conduction studies (NCSs) can determine whether a neuropathy is due to injury to the nerve axon (axonal neuropathy) or to the myelin sheath (demyelinating neuropathy). As the number of…
Polyneuropathy that involves the distal aspects of the limbs (at least initially) in a symmetric pattern is a common neurologic presentation. Sometimes referred to as a “stocking-glove” distribution, the most…
Electrophysiologic study of the peripheral nervous system typically involves nerve conduction studies (NCS) and needle examination of the muscle (electromyography; EMG). NCS/EMG is useful to localize a lesion (root/plexus/nerve/neuromuscular junction/muscle)…
