A Structured Approach to the Diagnosis of Peripheral Nervous System Disorders

Zachary N. London, MD, FAAN Peripheral Nerve and Motor Neuron Disorders p. 1130-1160 October 2020, Vol.26, No.5 doi: 10.1212/CON.0000000000000922
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PURPOSE OF REVIEW Neuroanatomic localization and pattern recognition can be used to diagnose both focal lesions and generalized disorders of the peripheral nervous system. This article describes the nature and pattern of sensory and motor deficits associated with lesions of specific spinal nerve roots, plexus, or peripheral nerves. It also describes the patterns of sensory and motor deficits that suggest multifocal or generalized disorders of the motor neurons, sensory neurons, and peripheral nerves.

RECENT FINDINGS The pattern of sensory and motor deficits may be used to distinguish lesions of the peripheral nervous system from those of the central nervous system. The spinal roots, nerve plexus, and peripheral nerves supply specific muscles and receive sensory input from distinctive cutaneous regions. Focal lesions of these structures therefore produce characteristic patterns of sensory and motor deficits. Multifocal or generalized disorders of the peripheral nervous system may be distinguished by categorizing their sensory and motor involvement, proximal and distal predominance, and degree of symmetry. Serum tests, CSF analysis, electrodiagnostic studies, MRI, ultrasound, nerve biopsy, and skin biopsy have unique roles in the diagnosis of suspected neuromuscular disorders.

SUMMARY A structured approach to the diagnosis of nerve and motor neuron disorders can lead to hypothesis-driven diagnostic testing. Ancillary tests should be reserved for cases in which confirming or refuting a diagnosis will change patient management.

Address correspondence to Dr Zachary N. London, 1324 Taubman Center, 1500 E Medical Center Dr, Ann Arbor, MI 48109, [email protected].

RELATIONSHIP DISCLOSURE: Dr London has received personal compensation for speaking engagements from the American Academy of Neurology, the American Association of Neuromuscular & Electrodiagnostic Medicine, the American Clinical Neurophysiology Society, the University of Pennsylvania, and the University of Rochester.


© 2020 American Academy of Neurology.