Central somatosensory conduction slowing in adults with isolated elevated plasma level of homocysteine

Abstract

Aim: Elevated plasma level of homocysteine (eHcy) is a recognized risk factor for dementia. However, whether the central conduction is affected in patients with an isolated eHcy is unknown. In this study, we addressed whether central conduction is altered in adults with eHcy. Methods: Evoked potential studies including somatosensory (SSEP), visual (VEP) and brainstem auditory evoked potentials (BAEP), were performed to evaluate central conduction in patients with isolated eHcy. Results: Nine SSEP, 7 VEP, and 6 BAEP were studied in 9 patients with eHcy (age: 63.3 ± 7.5 years old, mean ± standard deviation, male/female: 4/5). SSEP with median nerve stimulation was delayed in peak latency of N9 (5/9/55.6%, abnormal/total subjects/percentage), N13 (7/9/77.8%), N20 (6/9/66.7%), and/or interpeak latency of N9-N13 (5/9/55.6%), N13-N20 (5/9/55.6%), and N9-N20 (4/9/44.4%). There was one delayed P100 latency (1/7/14.3%) in 7 VEP. BAEP was within normal limits in all the 6 subjects tested. Conclusion: Our pilot study provided neurophysiologic evidence of central conduction slowness in patients with eHcy, which may be due to a large diameter fiber dysfunction within the somatosensory, but not the visual and auditory, white matter pathway. The central conduction slowing in eHcy may be relevant to the pathophysiologic background for slowing the central processing.

Homocysteine and Peripheral Neuropathy

“…Neurophysiologic studies of patients with eHcy-induced PN showed evidence of mildly mixed demyelination and distal axonal degeneration, suggestive of a mild largefiber sensorimotor neuropathy [6]. Interestingly, central somatosensory large fibers may also be involved [7]. eHcy exerts neurotoxic effects causing neuronal injury by overstimulating NMDA receptors, inducing calcium influx [8] which provokes excitotoxic and oxidative stress, damages DNA and leads to neuronal death or apoptosis, which has been demonstrated in laboratory in vitro cell culture and in vivo animal studies [9].…”