Morphometric changes of sensorimotor structures in focal dystonia

Abstract

Idiopathic cervical dystonia (CD) and benign essential blepharospasm (BEB) are the most common forms of focal dystonia. Previous autopsy and imaging studies suggested that these disorders are not accompanied by structural brain abnormalities. However, recent brain voxel-based morphometry (VBM) studies of these conditions suggest that there actually may be changes in gray matter. The objective of this stdy was to detect possible gray matter abnormalities in patients with CD and BEB using VBM and to compare the results between the two conditions and with age- and gender-matched controls. High-resolution MRI was employed to evaluate healthy controls and individuals with BEB and CD. Eleven BEB, 9 CD, and 14 healthy control subjects were imaged. VBM revealed alterations of gray matter structures involved in sensorimotor processing in the individuals with focal dystonia. In CD subjects there was increased gray matter in the thalamus, caudate head bilaterally, superior temporal lobe, and left cerebellum, while gray matter was decreased in the putamen bilaterally. BEB subjects had increased gray matter in the caudate head and cerebellum bilaterally as well as decrease in the putamen and thalamus bilaterally. These findings strongly underline the recent notion that idiopathic focal dystonias might have a detectable structural correlate. They also demonstrate structural similarities of the investigated focal dystonias, possibly reflecting a shared common pathophysiological origin.

A Transverse and Longitudinal MR Imaging Voxel-Based Morphometry Study in Patients with Primary Cervical Dystonia

“…6 By contrast, unlike other authors who reported a GM increase in the thalamus, caudate nucleus, and left cerebellum, 6 we found no GM volume increase in any sensorimotor network structure. We attribute the discrepancies to several factors: We studied a larger sample of patients with CD than those studied by Obermann et al 6 and Egger et al 7 ; our patients had a longer disease duration and were younger than those reported by others. 6,7 Mapping the progression of changes in GM volume with time in the same patients showed that GM volumes in the left primary sensorimotor cortex decreased further during the subsequent 5-year interval.…”

“…We attribute the discrepancies to several factors: We studied a larger sample of patients with CD than those studied by Obermann et al 6 and Egger et al 7 ; our patients had a longer disease duration and were younger than those reported by others. 6,7 Mapping the progression of changes in GM volume with time in the same patients showed that GM volumes in the left primary sensorimotor cortex decreased further during the subsequent 5-year interval. The GM changes we found in patients with CD suggest a disease-related loss of neuronal density in the caudate, putamen, and sensorimotor cortex.…”

“…3,4 Cross-sectional studies using MR imaging-VBM, a technique that can evaluate intergroup and intragroup voxel-wise differences in GM volumes, have detected ultrastructural brain changes in apparently normal brain tissue in patients with CD. [5][6][7] In these patients, regional GM abnormalities have been described in both subcortical and cortical structures, though controversial findings have been reported by the various authors. Whereas some found GM volume focally increased in the motor cortex, cerebellum, and GPi but decreased in the caudal SMA, dorsolateral frontal cortex, and visual cortex in patients with CD, 5 others reported increased GM volumes in the thalamus, caudate head, superior temporal lobe, and left cerebellum.…”

“…Whereas some found GM volume focally increased in the motor cortex, cerebellum, and GPi but decreased in the caudal SMA, dorsolateral frontal cortex, and visual cortex in patients with CD, 5 others reported increased GM volumes in the thalamus, caudate head, superior temporal lobe, and left cerebellum. 6 Yet others described an increased GM volume (though not statistically significant) in the GPi and SMA. 7 These inconsistent results, the small numbers of patients with CD studied, and the lack of longitudinal VBM studies leave the topographic distribution of brain abnormalities in CD unclear.…”

Dystonia Pathophysiology: A Critical Review

“…Contradictory results have been found with voxel-based morphometry. Some studies noticed increased volumes in the sensorimotor cortex (132), putamen (133), globus pallidus (134) and cerebellum (135), but other decreased volumes in the putamen (136) sensorimotor cortex (137), cerebellum and thalamus (136,137). These results must be interpreted in a phenomenological perspective since dfferent types of dystonia may yield different results.…”