Movement-related cortical potentials in patients with Machado-Joseph disease.

OBJECTIVE: Movement-related cortical potentials (MRCP; nomenclature of MRCP components according to Shibasaki and Hallett (Shibasaki H, Hallett M. What is the Bereitschaftspotential? Clin Neurophysiol 2006;117:2341-56) were studied in patients with Machado-Joseph disease (MJD) to elucidate the pathophysiology of voluntary movement. METHODS: We studied nine genetically proven MJD patients and eight age-matched healthy subjects. Multi-channel electroencephalogram (EEG) recordings were obtained during self-paced fast extensions of the wrist. EEG epochs were time-locked to electromyography (EMG) onset or offset of the voluntary EMG burst and averaged. RESULTS: In the MJD patients, the early Bereitschaftspotential (early BP, -1500 to -500ms) was not affected but the late BP was reduced over the central midline area and contralaterally to the movement side. The amplitude of the fpMP, a post-movement MRCP component, was also reduced. In addition, the offset cortical potential in the first 500ms after EMG offset (Moff+500) was attenuated bilaterally over a wide cortical area. CONCLUSIONS: Findings suggest that cortical activations associated with the initiation and termination of a voluntary movement are impaired in MJD patients. SIGNIFICANCE: Abnormalities of pre- and post-movement MRCP components provide researchers with pathophysiological insight into voluntary motor dysfunction in MJD.

Diminution of basal ganglia dopaminergic function may play an important role in the generation of akinetic mutism in a patient with anterior cerebral arterial infarct.

We report the clinical features and dopamine transporter [2-[[2-[[[3-(4-chlorophenyl)-8-methyl-8-azabicyclo[3.2.1]oct-2-yl]methyl](2-mercaptoethyl)amino]ethyl]amino]ethanethiolato(3-)-N2,N20,S2,S20]oxo-[1R-(exo-exo)]-[99mTc] technetium([99mTc]TRODAT-1) image finding in an 86-year-old woman with akinetic mutism due to infarction of bilateral anterior cerebral arterial territories. TRODAT-1 is a cocaine analogue that can be labeled with technetium-99m and bound to the dopamine transporter (DAT) site. It reflects primarily the integrity of presynaptic dopamine neuron terminals. With the evolution of the clinical features, the TRODAT SPECT images change from bilateral diminution of radioactivity uptake at the 81st-day check point to normal pattern at the 6-month one when the akinetic mute manifestations were nearly gone. This novel illustration suggests that the akinetic mutism caused by anterior cerebral arterial infarct is closely linked to the perturbation of the subcortical dopaminergic system. And the amelioration of the clinical features concordantly evolved with the restoration of the dopaminergic function.

Clinical, imaging and electrophysiological studies of corticobasal degeneration.

Corticobasal degeneration (CBD) is a rare neurodegenerative disorder characterized by distinctive clinical manifestations including asymmetric akinetic-rigid syndrome and higher cortical dysfunctions. We characterized the clinical, electrophysiological and imaging presentations in four patients with CBD. All patients exhibited unilateral hand dystonia, rigidity and apraxia, but showed no significant response to levodopa therapy. Surface electromyography demonstrated short duration and stimulus-sensitive myoclonus in three of the four patients. On the other hand, there was no "giant" SEPs (somatosensory evoked potentials), and the backaveraged electroencephalography did not show any jerk-locked cortical potentials. Brain magnetic resonance imaging showed asymmetrical cortical atrophy. [99mTc]HMPAO single-photon emission computed tomography (SPECT) revealed decreased regional cerebral blood flow in the frontoparietal areas and thalamus opposite to the more severely affected limb. [99mTc]TRODAT-1 SPECT showed decreased uptake in the striatum of the affected hemisphere. These data supported that there are abnormal cortical excitability and asymmetric pathological change of the affected hemisphere in the patients with CBD.