CHAPTER 71 - Peripheral neuropathic pain: Classifications, mechanisms, and treatments

Abstract

Peripheral neuropathic pain (PNP) is a commonly presenting subset of clinical disorders encompassing such classic diseases as painful diabetic neuropathy, trigeminal neuralgia, and chronic regional pain syndrome. Peripheral pain with distinct neuropathic characteristics is found in 6.9-10% of the general population. Painful Diabetic Peripheral Neuropathy occurs in 1/3 of patients with Diabetic Peripheral Neuropathy (DPN), including up to 5.7 million patients in the United States alone. Peripheral neuropathic pain generally involves a lesion of a peripheral nerve. When the injury or disease affects the peripheral nervous system, then associated pain is called peripheral neuropathic pain. PNP differs from central pain syndromes by the presence of positive and negative sensory phenomena which offer a challenge to patients and providers to describe and categorize. It is characterized by negative sensory phenomena such as loss of sensory perception, often reported as numbness, and positive sensory findings such as pain, allodynia, and hyperalgesia. This translates to the physical examination findings of a deficit in at least one modality, for example, light touch, and concurrent positive sensory phenomena to another sensory modality, such as dysesthesia to cold. Treatments of PNP are directed at the pathophysiology and symptoms, including vitamin supplementation, pain modulating medications, therapeutic modalities, neuromodulation, and surgery. A definitive restructuring of this cluster of diseases is underway, utilizing common phenotypic findings from examinations.