Idiopathic Polyneuropathy
ABSTRACT & COMMENTARY
By Michael Rubin, MD
Professor of Clinical Neurology at NewYork-Presbyterian Hospital, Cornell Campus
Dr. Rubin is on the speaker’s bureau for Athena Diagnostics and does research for Pfizer and Merck.
Synopsis: Patients presenting with symptoms of polyneuropathy but who have neither neurological signs of polyneuropathy nor electrophysiological studies confirming a polyneuropathy have a good outcome at least 2 years after presentation.
Source: Rosenberg NR, et al. Follow Up of Patients With Signs and Symptoms of Polyneuropathy Not Confirmed By Electrophysiological Studies. J Neurol Neurosurg Psychiatry. 2005:76:879-881.
Patients with symptoms and signs of polyneuropathy, yet with normal electrophysiological studies, are a common conundrum in clinical practice. What can we counsel these patients regarding prognosis? Retrospective review of all such patients seen between 1993-1998 in an outpatient department of a university medical center was undertaken to address this question. All patients were symptomatic, complaining of tingling, burning, pain, numbness, muscle weakness, cramps, or stiffness, and had signs consistent with polyneuropathy, including impaired vibratory, pin-prick, temperature, joint-position, light touch sensation, hyperpathia, muscle weakness, wasting, fasciculations, and loss of deep tendon reflexes. Patients over 65 years were considered normal despite absence of ankle reflexes, atrophy of the extensor digitorum brevis muscle, or impaired vibration sensation at the big toe. All patients had undergone nerve conduction studies, including thermo-sensory threshold testing if a small fiber neuropathy was suspect. Follow-up, performed at 2 years, consisted of the physical section of the Sickness Impact Profile (SIP) categorized as a good (minor symptoms, score < 75 percentile) or poor outcome (severely disabled, score > 75 percentile).
Among 489 persons referred for possible polyneuropathy between 1993-1998, 397 underwent electrodiagnostic studies, 139 of which did not demonstrate evidence of neuropathy. Of these, clinical criteria for neuropathy were not fulfilled in 27 who were excluded, and an additional 38 were not available for follow-up at 2 years, leaving 74 subjects eligible for this study, 35 with symptoms only, and 39 with both symptoms and signs.
Among 15 women and 20 men with symptoms only, mean age was 51 years. Three yielded a diagnosis by follow-up, one each with conversion, erythromelalgia, and ciguatera intoxication. Only one patient among the 35 suffered a poor outcome due to unrelated multiple embolic infarcts. Among 19 women and 20 men with both symptoms and signs, mean age was 58 years, and 24 yielded diagnoses, including spinal stenosis (n = 9), multiple sclerosis (n = 5), dural arteriovenous fistula (n = 2), and 1 each with meningioma, intramedullary tumor, plexopathy, radiculopathy, intermittent claudication, spinal muscular atrophy, syringomyelia, and B12 deficiency. Fifteen of 74 patients were found to have risk factors for polyneuropathy, encompassing diabetes or alcohol abuse, or both, and renal disease.
Diagnosis in idiopathic chronic polyneuropathy is possible in over 60% of patients with both symptoms and signs, even in the absence of electrodiagnostic confirmation, but in less than 10% with symptoms only. Patients in the latter group may be reassured that prognosis is excellent.
Commentary
Do statins (HMG-CoA-reductase inhibitors) cause idiopathic polyneuropathy (IPN)? No, it appears they do not. From a database of 915,066 patients, encompassing 23 affiliated hospitals in Utah and neighboring states, 272 patients were identified as having been admitted with a diagnosis of IPN over a 4-year period. None carried a diagnosis of diabetes, renal insufficiency, alcoholism, cancer, AIDS, Lyme disease, heavy metal intoxication, or hypothyroidism. Neither dosage nor duration of statin use prior to the diagnosis was found to be significantly different in IPN patients, compared to 1360 matched controls.
By Michael Rubin, MD Professor of Clinical Neurology at NewYork-Presbyterian Hospital, Cornell Campus Dr. Rubin is on the speakers bureau for Athena Diagnostics and does research for Pfizer and Merck.You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
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