Effects of Spontaneous Chronic Hypoglycemia on Central and Peripheral Nervous System in Insulinoma Patients before and after Surgery: A Neurophysiological Follow-Up

Abstract

To investigate the effects of spontaneous chronic hypoglycemia on the peripheral and central nervous system, a multimodal neurophysiological evaluation [median somatosensory (mSEP), brain stem auditory (BAEP), and visual (VEP) evoked potentials recordings] was performed in seven insulinoma patients before and 3 and 6 months after surgical removal of tumor.Before surgery, mSEP findings showed abnormal reduction in peripheral wrist-Erb conduction velocity in three patients as well as a pathological increase in Erb-N13, N13-N20, and Erb-N20 conduction times in five cases. BAEP and VEP recordings gave pathological results in two patients. Moreover, during hypoglycemia, the III-V and I-V interpeak latencies of BAEPs were significantly prolonged (P Ͻ 0.01 and P Ͻ 0.005, respectively) compared to recordings in euglycemia.After 6 months, a mSEP recovery, even if partial was noted in four patients, BAEPs were normalized in one case, and VEPs were unmodified. Compared to presurgery data, these recordings showed a significant (P Ͻ 0.05), but incomplete, shortening of BAEPs (III-V and I-V interpeak latencies) and mSEPs (Erb-N13 and Erb-N20 conduction times).Our findings demonstrate that multiple and selective neurophysiological abnormalities are present in insulinoma patients, confirm that hypoglycemia impairs suddenly brain stem function, and show that after tumor removal, long recovery times for improvement of some neurophysiological anomalies are requested. (J Clin Endocrinol Metab 82: 1447-1451, 1997) I T IS WELL known that hypoglycemia depresses cerebral energy metabolism. Thus, it is likely to cause a temporary impairment of cerebral functions and, less frequently, can produce permanent brain damage and death (1, 2). Cortical and hippocampal atrophy and ventricular enlargement may occur (3); sometimes diffuse demyelinization has been observed (3).At the peripheral level, insulin-induced hypoglycemia has been shown to produce acute axonal degeneration in both nondiabetic and diabetic animals (4) and to alter the anterograde fast components of axonal transport in rats (5). Furthermore, a distal symmetrical predominantly motor neuropathy is a rare syndrome that can occur in patients with hypoglycemia secondary to insulinoma (6 -9).During the past few years, a number of studies have examined the effects of hypoglycemia on central nervous system functions, and neurophysiological as well as neuropsychological changes have been noted (10 -14). However, the extent and mechanisms of nervous system impairment during hypoglycemia have not yet been fully described.The electrophysiological techniques potentially offer objective means of assessing peripheral and central nervous system function (15). Moreover, the recording of electrical events occurring along the somatosensory, auditory, and visual pathways constitutes a noninvasive diagnostic tool in the detection of even subclinical nervous system impairments.To our knowledge, peripheral along with central nervous system function in patients suffering from spontaneous hyp...

Effect of Insulin‐Induced Hypoglycaemia on the Peripheral Nervous System: Focus on Adaptive Mechanisms, Pathogenesis and Histopathological Changes

“…In support of this, in another study, the induction of repeated hypoglycaemic episodes of 3 h/day on four consecutive days in rats caused several endoneurial microvessel changes, including endothelial swelling and oedema of the endoneurium (Table ), which were shown to be partially reversible after a 7‐day recovery period with less severe endothelial swelling and resolution of endoneurial oedema . In agreement, humans with insulinomas show partial resolution of clinical symptoms (mainly sensorimotor disturbances) after resection of the insulinomas , indicating that nerve and muscle changes induced by the hyperinsulinaemic hypoglycaemia accompanying insulinomas are reversible to some degree.…”

Hypoglycemic neuropathy

“…These abnormalities may show some long-term recovery [101]. These abnormalities may show some long-term recovery [101].…”

“…However, since then few studies dealing with the effects of insulinoma-related hypoglycemia on the PNS of patients have been published. Neurophysiological analysis has revealed slowed muscle nerve conduction velocities [64,101] and there is electromyographic evidence for denervation of skeletal muscle [53,131]. Neurophysiological analysis has revealed slowed muscle nerve conduction velocities [64,101] and there is electromyographic evidence for denervation of skeletal muscle [53,131].…”

Neurologic damage in hypoglycemia

“…Some degree of long-term recovery from these abnormalities has been achieved through surgical removal of the islet cell tumors (Pozzessere et al, 1997;Olsen and Abraham, 1999;Heckmann et al, 2000;Suzuki et al, 2007). Some degree of long-term recovery from these abnormalities has been achieved through surgical removal of the islet cell tumors (Pozzessere et al, 1997;Olsen and Abraham, 1999;Heckmann et al, 2000;Suzuki et al, 2007).…”