Corpus callosum volume and interhemispheric transfer in multiple sclerosis

The corpus callosum (CC) is frequently compromised in patients with multiple sclerosis (MS). Structural and functional measurements of the CC may be useful to monitor the progression of the disease. The aim of this pilot study was to determine if bimanual tactile temporal thresholds correlates with CC volume. A tactile temporal threshold is the longest temporal interval that separates the onsets of two tactile stimuli when they are judged by the observer as simultaneous. Judgments to bimanual stimulations require interhemispheric transfer via the CC.

Thresholds were examined in MS patients and matched controls. Magnetic resonance (MR) images were acquired on a 3T MR system within 48 hours of clinical assessment and measurement of thresholds.

Corpus callosum volume was assessed by using a semiautomatic livewire algorithm. The CC volume was smaller (by 21% on average, p < 0.01) and thresholds were higher (by 49% on average, p < 0.03) in MS patients when compared to controls. A significant correlation (r = -0.66, p = 0.01) between CC volume and thresholds emerged for the MS patients.

Measuring treatment benefits of neuroprotective and repair therapies is a well recognized challenge in MS research. The overall findings of this study suggest that these measurements, which involve the transfer of information interhemispherically via the CC, may be promising outcome measures that warrant further scientific exploration to develop a model to measure recovery.