Longitudinal changes of motor cortical excitability and transcallosal inhibition after subcortical stroke.

OBJECTIVE: A general lack of longitudinal studies on interhemispheric interactions following stroke led us to use transcranial magnetic stimulation (TMS) to examine changes in corticospinal/intracortical excitability and transcallosal inhibition over a 1-year period following subcortical stroke. METHODS: We measured TMS parameters such as motor threshold (MT), short-interval intracortical inhibition (SICI), and ipsilateral silent period (iSP) and evaluated clinical scores at three time-points (T1, T2, and T3) in 24 patients and 25 age-matched healthy subjects. RESULTS: At T1, we observed reduced MTs and SICIs with prolonged iSPs in the unaffected hemisphere (UH). In contrast, increased MTs and reduced SICIs were observed in the affected hemisphere (AH). These abnormalities gradually reduced and no MEP response to TMS at T1 predicted a worse prognosis. The prolonged iSP at T1 was associated with more severe impairments, but it did not necessarily predict a worse prognosis after 1year. CONCLUSIONS: UH excitability was increased at the post-acute time-period, which may have resulted in enhanced transcallosal inhibition to the AH. However, it is unclear whether there was a causal relationship between the enhanced transcallosal inhibition and the extent of clinical recovery. SIGNIFICANCE: This is the first study to demonstrate changes in transcallosal inhibition over a longitudinal period following stroke.

Motor excitability after the C reflex in cortical reflex myoclonus.

Twelve patients with cortical reflex myoclonus were electrophysiologically investigated. From the results of the recording of the C reflex during voluntary contraction, cortical reflex myoclonus was classified into three subtypes: type I; C reflex with recurrent C reflex (C'), type II; double C reflexes (C1, C2) and type III; C reflex with evident inhibition. The jerk-locked motor evoked potential (MEP) showed different mechanisms in the C' and C2 reflexes. The findings of cortical delay, facilitatory effect of peripheral stimulation on MEP and jerk-locked MEP indicate that both cortical reflex myoclonus and the silent period after the C reflex in patients with type III cortical reflex myoclonus might originate from a change of cortical excitability of the motor cortex.

[Longitudinally extensive spinal cord lesion in a case of Neuro-Behçet disease].

A 56-year-old right-handed man with recurrent orogenital aphtoid ulcers and bilateral uveitis had presented with memory disturbance, dressing apraxia and constructional apraxia at age 53. Neuro-Behçet disease was diagnosed based on pathergy test results and positivity for HLA-B51. Four months after azathioprine was introduced, he presented with subacute spastic paraparesis and urinary retention at age 56. Neurological examination demonstrated hyperreflexia in the lower limbs without pathological reflexes. He also showed memory disturbance, dressing apraxia and constructional apraxia. Spinal cord MRI showed a longitudinally extensive spinal cord lesion (LESCL) from C1 to Th3 with partial gadolinium enhancement from C6 to C8. Brain MRI showed moderate atrophy of the right temporal and parietal lobes without contrast enhanced lesion. There were hyperintense lesions in the pons, bilateral periventricular white matter and right parietal subcortical white matter. Cerebrospinal fluid analysis showed mild lymphocytic pleocytosis. After intravenous methylprednisolone treatment, clinical symptoms largely resolved and the abnormal intensities with contrast enhancement of the cord disappeared. However, higher cortical dysfunctions were not changed. LESCL may reflect inflammatory venous vasculitis with edema extending along the neural fibers since the lesion shows excellent responses to steroid without neurological sequelae. Differential diagnosis of neurological diseases demonstrating LESCL should include Neuro-Behçet disease.