ABSTRACT Objective: To assess the function of the central and peripheral nervous systems in patients with untreated acromegaly. Methods: We recorded the somatosensory evoked potentials (SSEPs) and brain stem auditory evoked poten- tials (BAEPs) in 10 patients with untreated acromegaly of brief duration and in 20 age- and sex-matched healthy control subjects to evaluate the function of the central nervous system and at least the median and tibial compo- nents of the peripheral nerves. Electrophysiologic studies were done at the time of diagnosis and before the initia- tion of any treatment for acromegaly. We also studied the distal motor latency, nerve conduction velocity, com- pound muscle action potentials, and F response in the per- oneal nerve; the sensory nerve conduction velocity and sensory potential amplitude were measured in the sural nerve. Results: The mean duration of acromegaly (ex- pressed as time elapsed since patients first recognized signs or symptoms) was 2.4 years. The N 9 and N 13 laten- cies in median SSEPs and the N 22 latency in tibial SSEPs were significantly prolonged in patients with acromegaly in comparison with the control group; however, central nervous system components of SSEPs and all components of BAEPs were normal. We also noted abnormalities in peroneal motor and sural sensory nerves. No correlation was found between the neurophysiologic data and the basal growth hormone level, the fasting blood glucose level, or the duration of disease. Conclusion: Our results suggest that peripheral, but not central, nervous system involvement exists in patients with untreated acromegaly of short duration. (Endocr Pract. 1997; 3:118-122) INTRODUCTION Generalized peripheral nerve dysfunction is common in patients with acromegaly (1-4). This neuropathy was found to be predominantly sensory in nature, but severe muscle weakness and wasting have also been reported (5,6). Although believed to be related to the disease process, the generalized peripheral neuropathy was found to occur independently of the associated carbohydrate intolerance, growth hormone (GH) levels, and other endocrinologic dysfunction in this disorder (1,3,6). Moreover, the incidence of unilateral or bilateral carpal tunnel syndrome was found to be 35 to 50% in patients with acromegaly (7-9). Compression neuropathies also have been reported (1,6). To date, however, no study has evaluated the central and peripheral nervous systems by using the brain stem auditory evoked potentials (BAEPs) or somatosensory evoked potentials (SSEPs) in patients with acromegaly. In this study, we recorded SSEPs and BAEPs to assess the function of the central nervous sys- tem and at least the median and tibial components of peripheral nerves in patients with acromegaly. PATIENTS AND METHODS Study Cohort The study group consisted of 10 patients (9 men and 1 woman; from 21 to 65 years old [mean, 32.3 ± 16.2]) with untreated active acromegaly. The diagnostic criterion for active acromegaly used in this study was an elevated fasting nonstressed (basal) GH level that showed either a paradoxic increase or a failure to suppress below 2 ng/mL during an oral glucose tolerance test (10). Patients who had abnormal results on a glucose tolerance test or had hypothyroidism were excluded from our study. Twenty healthy persons (18 men and 2 women; from 20 to 64 years old [mean, 32.0 ± 15.5] and matched for age and sex with the patients who had acromegaly) were selected as control subjects. A history was elicited, and a complete medical examination, including neurologic assessment, was performed in all patients. No patient had other con- current disorders or factors that could have caused polyneuropathy or degenerative disease of the central ner- vous system (such as diabetes mellitus, uremia, collagen disease, cancer chemotherapy, or anticonvulsant therapy). Furthermore, no patient or control subject had a history of a central nervous system disorder. The duration of acromegaly (expressed as time elapsed since the patients first recognized signs or symp- toms) was estimated on the basis of historical data—such as increasing shoe or ring size, coarsening of facial fea- tures, or development of prognathism. Because determin- ing the precise beginning of disease in patients with acromegaly is difficult, we uniformly relied on the patients’ recollection of initial signs or symptoms. All patients and control subjects were informed about the objective of and the procedures involved in the study, and they provided written consent. The protocol had been approved by the Local Ethical Committee of Gulhane School of Medicine. Original Article CENTRAL AND PERIPHERAL NEURAL RESPONSES IN ACROMEGALY Metin Ozata, M.D., 1 Abdullah Ozkardes, M.D., 2 Zeynel Beyhan, M.D., 1 Ahmet Corakci, M.D., 1 and M. Ali Gundogan, M.D. 1 Submitted for publication April 22, 1996 Accepted for publication July 12, 1996 From the Departments of 1 Endocrinology & Metabolism and 2 Neurology, Gulhane School of Medicine, Etlik-Ankara, Turkey. Correspondance to Dr. M. Ozata, Department of Endocrinology, Gulhane School of Medicine, Etlik-Ankara, Turkey 06018. Copyright © 1997 AACE. 118 ENDOCRINE PRACTICE Vol. 3 No. 3 May/June 1997