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Our findings indicate that the hand area in the cerebral motor cortex is located in the middle to lower portion of the anterior wall of the central sulcus, that is, in Brodmann area 4. We present our 8 patients showing isolated hand palsy due to a discrete cortical infarction on MRI to expand the knowledge about cortical localization of the hand area.

The authors studied 11 patients with subinsular stroke (subIS) located in a deep border zone between lenticulostriate arteries and small insular cortical penetrating branches of the middle cerebral artery. The typical clinical features of subIS were motor deficits (11 patients), sensory disturbances (6 patients), transcortical motor aphasia and hypophonia (2 patients), and transient dysphagia at stroke onset (5 patients). Large artery disease and cardioembolic mechanisms may give rise to subIS by hemodynamic mechanisms.

Recently it has been proposed that corticobulbar innervation of the lower facial muscles is bilateral, that is from both right and left sides of the motor cortex. The objectives of this study were, i) to evaluate the corticonuclear descending fibers to the perioral muscles and, ii) to determine how central facial palsy (CFP) occurs and often recovers rapidly following a stroke. Eighteen healthy volunteers and 28 patients with a previous history of a stroke and CFP (mean ages: 51 and 61 years) were investigated by TMS (transcranial magnetic stimulation) with a figure of eight coil. Intracranial facial nerve and cortical motor evoked potentials (MEPs) were recorded from the perioral muscles. The periorbital MEPs were also studied. The absence of MEPs in both perioral muscles with TMS of the affected hemisphere was the most obvious abnormality. Also, central conduction time was significantly prolonged in the remaining patients. The mean amplitude of the affected hemisphere MEPs was diminished. The amplitudes of the unaffected hemisphere MEPs recorded from the intact side were enhanced especially in the first week following the stroke. During TMS, only the blink reflexes were elicited from the periorbital muscles due to stimulus spreading to trigeminal afferent nerve fibers. It is concluded that perioral muscles are innervated by the corticobulbar tract bilaterally. CFP caused by a stroke is generally incomplete and mild because of the ipsilateral cortical and multiple innervations out of the infarction area, and recovers fast through cortical reorganisation.