Asymmetrical delayed encephalopathy after acute CO intoxication: A case report

A rare case of Holmes tremor in a worker with occupational carbon monoxide poisoning

Parkinsonism and encephalopathy are frequently seen in patients who survive carbon monoxide (CO) poisoning. Neurological findings associated with CO poisoning can emerge immediately after cessation of exposure or following a brief period of pseudo-recovery. When present, the tremor associated with CO poisoning is typical of the postural/intention type. Here, we report on a rare case of toxic encephalopathy with a dominant-hand Holmes-type tremor, characterized by resting, as well as postural and kinetic/intentional components, in a previously healthy 53-year-old man exposed to CO while actively engaged in the process of performing a physically demanding skilled labor task. The unique neuropathological and functional changes that give rise to Holmes-type tremor and how this relates to the selective vulnerability of the inhibitory indirect pathway of the basal ganglia to glutamatergic excitotoxicity mediated by tissue hypoxia are discussed.

Altered white matter metabolism in delayed neurologic sequelae after carbon monoxide poisoning: A proton magnetic resonance spectroscopic study

Proton magnetic resonance spectroscopy ((1)H-MRS) was recently used to examine altered metabolism in the white matter (WM) of patients experiencing carbon monoxide (CO) poisoning; however, only a small number of patients with delayed neurologic sequelae (DNS) were analyzed. We aimed to detect altered metabolism in the WM of patients with DNS using (1)H-MRS; to explore its clinical relevance in the management of patients experiencing CO poisoning. Patients experiencing acute CO poisoning underwent (1)H-MRS and cerebrospinal fluid (CSF) examination within 1week and at 1month after acute poisoning. Metabolites including choline-containing compounds (Cho), creatine (Cr), N-acetylaspartate (NAA), and lactate were measured from the periventricular WM. Myelin basic protein (MBP) concentrations were measured in CSF. Fifty-two patients experiencing acute CO poisoning (15 with DNS, 37 without DNS; median age, 49years; 65% males) underwent (1)H-MRS. Within 1week, NAA/Cr ratios, reflecting neuroaxonal viability, were lower in patients with DNS than in those without DNS (P<0.05). At 1month, when 9 of 15 patients (60%) developed DNS, Cho/Cr ratios were higher, and NAA/Cr and NAA/Cho ratios lower in patients with DNS (P=0.0001, <0.0001, and <0.0001, respectively), indicating increased membrane metabolism and decreased neuroaxonal viability. (1)H-MRS parameter abnormalities correlated with the elevation of MBP in CSF. The presence of a lactate peak was a predictor for a poor long-term outcome. (1)H-MRS within 1week may be useful for predicting DNS development; (1)H-MRS at 1month may be useful for discriminating patients with DNS and predicting long-term outcomes.