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Original Article

Central somatosensory conduction slowing in

adults with isolated elevated plasma level of

homocysteine

Jin Jun Luo , Favio Bumanlag , Ramin Ansari , Ya-Mei Tang , Nae J. Dun 2
3
1
1
1,2
1 Department of Neurology, Temple University School of Medicine, Philadelphia, PA 19140, USA.
2 Department of Pharmacology, Temple University School of Medicine, Philadelphia, PA 19140, USA.
3 Department of Neurology, Sun Yat‑Sen Memorial Hospital, Sun Yat‑Sen University, Guangzhou 510120, Guangdong, China.
ABSTRA CT
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.
Key words: central conduction, evoked potential, homocysteine, hyperhomocysteinemia

INTRODUCTION METHODS

Homocysteine (Hcy) is an intermediary metabolite Neurophysiology laboratory databank of evoked
of amino acid, methionine, during methylation. potentials and the charts of subjects with a clinical
Elevated plasma level of homocysteine (eHcy) diagnosis of eHcy-induced neuropathy [16] seen in the
have been observed in many neurologic and Neuromuscular Clinic were initially retrospectively
psychiatric disorders including stroke, [1,2] cognitive reviewed. The symptoms and signs of neuropathy
impairment, dementia, [3,4] Alzheimer’s disease, [5,6] included the presentation of numbness and tingling
Parkinson’s disease, [6,7] amyotrophic lateral sclerosis, in the distal limbs with a decreased sensation in a
[8]
depression, [6,9-12] schizophrenia and bipolar disorders glove- and/or stocking-like pattern. Data of clinical
and in an animal model, [13,14] indicating eHcy may presentations, physical and neurological examinations,
adversely cause central nervous system dysfunction. [15] history of concomitant comorbidities; and laboratory
Whether eHcy interferes with central conduction as the findings including plasma levels of homocysteine,
pathophysiologic background relevant to the central methyl malonic acid, vitamin B12 and folic acid were
processing slowness is unknown. We, therefore, studied collected. Laboratory data included mean corpuscular
the central conduction in patients with eHcy. volume of red blood cells, glucose, creatinine,
glycosylated hemoglobin, thyroid stimulating hormone,
Access this article online lipids and liver function panels; inflammatory and
Quick Response Code: infectious studies including erythrocyte sedimentation
Website: rate, C-reactive protein, antinuclear antibody, rapid
www.nnjournal.net
plasma reagin, lyme titers, hepatitis profile, and human
[8]
DOI: immunodeficiency virus. Subjects with an isolated
10.4103/2347-8659.149420 eHcy who completed evoked potential studies were
included. Subjects with an identifiable etiology, other

Corresponding Author: Dr. Jin Jun Luo, Departments of Neurology and Pharmacology, Temple University School of Medicine,
3401 North Broad Street, Suite C525, Philadelphia, PA 19140, USA. E‑mail: jluo@temple.edu

26 Neuroimmunol Neuroinflammation | Volume 2 | Issue 1 | January 15, 2015