Corticonuclear innervation to facial muscles in normal controls and in patients with central facial paresis

Abstract

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.

Changes in oro-facial function and hand-grip strength during a 2-year observation period after stroke

“…In contrast to the control group their chewing efficiency was not correlated to the number of occlusal units. This supports the hypothesis that the reduced chewing efficiency in stroke patients might rather be dominated by neurophysiological impairment of the oro-facial structures [32,33] than the dental state [2].…”

Lip muscle training in stroke patients with dysphagia

“…Spontaneous remission of dysphagia [6,7] and facial palsy is usually observed within 2Á3 weeks after the stroke incident [8]. In this early post-stroke period it is difficult to assess if improvement of dysphagia is a spontaneous improvement or due to any therapeutic interventions.…”

Longstanding Effect and Outcome Differences of Palatal Plate and Oral Screen Training on Stroke-Related Dysphagia

“…aspiration, cough, drooling, food leakage, leakage through the nose, long meal times, and retention of food in the mouth, resolve over the first 7 days in one third of patients [4][5][6]. After one month, remaining dysphagia of around 10% is regarded to be more or less of chronic character [7,8].…”