Chronic cryptogenic sensory polyneuropathy - Clinical and laboratory characteristics

Background: Chronic sensory-predominant polyneuropathy (PN) is a common cli nical problem confronting neurologists. Even with modern diagnostic approac hes, many of these PNs remain unclassified. Objective: To better define the clinical and laboratory characteristics of a large group of patients with cryptogenic sensory polyneuropathy (CSPN) ev aluated in 2 university-based neuromuscular clinics. Design: Medical record review of patients evaluated for PN during a 2-year period. We defined CSPN on the basis of pain, numbness, and tingling in the distal extremities without symptoms of weakness. Sensory symptoms and sign s had to evolve for at least 3 months in a roughly symmetrical pattern. Ide ntifiable causes of PN were excluded by history, physical examination findi ngs, and results of laboratory studies. We analyzed clinical and laboratory data from patients with CSPN and compared findings in patients with and wi thout pain. Results: Of 402 patients with PN, 93 (23.1%) had CSPN and stable to slowly progressive PN syndrome. These patients presented with a mean age of 63.2 y ears and a mean duration of symptoms of 62.9 months. Symptoms almost always started in the feet and included distal numbness or tingling in 86% of pat ients and pain in 72% of patients. Despite the absence of motor symptoms at presentation, results of motor nerve conduction studies were abnormal in 6 0% of patients, and electromyographic evidence of denervation was observed in 70% of patients. Results of laboratory studies were consistent with axon al degeneration. Patients with and without pain were similar regarding phys ical findings and laboratory test abnormalities. Only a few patients (<5%) had no evidence of large-fiber dysfunction on physical examination or elect rophysiologic studies. All 66 patients who had follow-up examinations (mean , 12.5 months) remained ambulatory. Conclusions: Cryptogenic sensory polyneuropathy is a common, slowly progres sive neuropathy that begins in late adulthood and causes limited motor impa irment. Isolated small-fiber involvement is uncommon in this group of patie nts. Management should focus on rational pharmacotherapy of neuropathic pai n combined with reassurance of CSPN's benign clinical course.