ABSTRACT
INTRODUCTION: We tested whether a change in head/neck position initiates head deviation in drug-naïve patients with cervical dystonia and to identify the electrophysiological and neuroanatomical correlates of dystonic head rotation. METHODS: Twenty-five consecutive drug-naïve patients with cervical dystonia and 25 healthy controls underwent the simultaneous surface electromyographic (EMG) recording of sternocleidomastoid (SCM) muscle contractions during head/neck position changes, blink reflex recovery cycle (BRrc), DAT-SPECT, and advanced structural neuroimaging analysis using voxel-based morphometry (VBM). RESULTS: Surface EMG recordings of SCM muscle activity during changes in head/neck position demonstrated an insignificant asymmetric low amplitude of the SCM muscle contractions in the horizontal position in both patients and controls, but an asymmetric high amplitude in SCM muscle contractions leading to abnormal head movements in vertical positions in patients with cervical dystonia. All controls had a symmetric low increase in amplitude of SCM muscle contractions in response to changes in head/neck position. VBM analysis in 19 patients showed abnormal decreases of gray matter (GM) volume in the bilateral motor (localized in the homunculus of the head) and premotor cortices when compared to controls. In addition, the side of these neuroanatomical changes was asymmetrically related to abnormal head deviations in these patients. All subjects had normal results during BRrc and DAT-SPECT. CONCLUSIONS: The passage from inactive horizontal position to active vertical head/neck posture initiates head deviation in drug-naïve patients with cervical dystonia, and the anatomical correlates of this dystonic head rotation is a restricted abnormal pattern of GM changes in the motor cortices.
Subject(s)
Electromyography , Head Movements/physiology , Magnetic Resonance Imaging , Motor Cortex/pathology , Neck Muscles/physiopathology , Neuroimaging/methods , Torticollis/physiopathology , Adult , Blinking , Case-Control Studies , Dopamine Plasma Membrane Transport Proteins/analysis , Female , Gray Matter/pathology , Humans , Male , Middle Aged , Motor Cortex/physiopathology , Muscle Contraction , Posture , Reflex, Abnormal , Rotation , Tomography, Emission-Computed, Single-Photon , Torticollis/pathologyABSTRACT
In this study, we used an automated segmentation of regions of interest and co-registration to diffusion tensor imaging (DTI) images to investigate whether microstructural abnormalities occur in gray structures of the frontal-subcortical circuits in patients with amyotrophic lateral sclerosis (ALS). Twenty-four patients with probable or definite sporadic ALS and 22 healthy controls were enrolled in the study. Thirteen out of 24 ALS patients and all of the control subjects underwent a detailed neuropsychological evaluation. DTI was performed to measure mean diffusivity (MD) and fractional anisotropy in the frontal cortex, caudate, putamen, globus pallidus, thalamus, amygdala and hippocampus. MD values of ALS patients were significantly higher in the frontal cortex (P = 0.023), caudate (P = 0.01), thalamus (P = 0.019), amygdala (P = 0.012) and hippocampus (P = 0.002) compared to controls. MD of these structures significantly correlated to a variable degree with neurological disability and neuropsychological dysfunctions. The increased MD values in several cortical and subcortical gray structures and their correlations with neuropsychological variables substantiate a multisystemic degeneration in ALS and suggest that dysfunctions of frontal-subcortical circuits could play a pivotal role in frontal impairment and behavioral symptoms in ALS patients.
Subject(s)
Amyotrophic Lateral Sclerosis/pathology , Brain/pathology , Adult , Aged , Aged, 80 and over , Amygdala/pathology , Basal Ganglia/pathology , Diffusion Magnetic Resonance Imaging , Diffusion Tensor Imaging , Female , Frontal Lobe/pathology , Humans , Male , Middle AgedABSTRACT
PURPOSE: This study is aimed at investigating the neuroanatomical patterns characterizing dystonic tremor in comparison with essential tremor. METHODS: Voxel-based morphometry and cortical thickness data of 12 patients with dystonic tremor, 14 patients with essential tremor and 23 age- and sex-matched healthy control subjects were analyzed. RESULTS: Patients with dystonic tremor showed a thickening and increased gray matter volume (surviving whole-brain correction for multiple comparisons) of the left sensorimotor cortex when compared to other groups. Otherwise, patients with essential tremor were characterized by a subtle atrophy of the anterior cerebellar cortex. DISCUSSION: Our multimodal structural neuroimaging study demonstrated that patients with dystonic tremor and essential tremor are characterized by different neuroanatomical abnormalities. The involvement of the sensorimotor cortex in patients with dystonic tremor suggests that this disorder may share some pathophysiological mechanisms with focal dystonia.
