Sensory Neuropathy

Excerpt

Sensory neuropathies refer to a host of diseases that result in loss of sensation throughout the body. Collectively, sensory neuropathies can result from a plethora of conditions. These sensory neuropathies may be subdivided into small fiber pain-dominant and large fiber ataxia-predominant pathologies.

Appropriate treatment and management are determined by sensory neuropathy classification, which is based on nerve size and degree of myelination. When assessing small fiber neuropathies, the small somatic Aδ and small unmyelinated C fibers are of particular interest. These fibers transmit noxious and thermal signals and regulate preganglionic sympathetic and parasympathetic function via the Aδ fibers and postganglionic autonomic function via the C fibers. Disruption of the normal physiological state of these fibers typically results in burning and shooting pain with paresthesia.

In contrast, large fiber neuropathies result from attenuating Aβ fibers, which regulate the proprioceptive signals of vibration and touch. Grossly speaking, patients with sensory ataxia likely possess deformation to the dorsal columns of the spinal cord as well as the dorsal root ganglia. Although ataxia is pathognomonic for large-fiber sensory neuropathy, subsequent damage to smaller fibers may occur. As such, some diseases may yield mixed etiology polyneuropathies, composed of small and large fibers (eg, diabetes mellitus), and present some of the most significant public health burdens in modern-day medicine.

Classic clinical findings include complaints of "pins and needles" and "electricity" in the affected extremities, which follow a stocking-glove pattern. Evaluation of sensory neuropathy primarily revolves around neurophysiological examination and dermatopathological studies such as skin biopsy, the current validated gold standard for diagnosing small fiber neuropathy. Guidelines on specific treatment modalities for sensory neuropathies have not been defined. The majority of the data regarding treatments are based on expert opinions, along with well-constructed research. Treatments include injection of intravenous immunoglobulins, methotrexate, corticosteroids, infliximab, plasma exchange, and various oral topical medications, depending on the etiology. This activity reviews the evaluation and management of patients with sensory neuropathies.