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At least 199 records · Page 11Linked to original sources
PubMed1992

Redirection of the hypoglossal nerve to facial muscles alters central connectivity in human brainstem.

Functional motor control requires perfect matching of central connectivity of motoneurones with their peripheral connections. However, it is not known to what extent central circuitry is influenced by target muscles, either during development or following a lesion. Surgical interventions aimed at restoring function following peripheral nerve lesions provide an opportunity for studying this interaction in the mature human nervous system. We have followed 8 patients in whom the hypoglossal nerve was anastomosed into a lesioned facial nerve, allowing voluntary contractions of the previously paralyzed muscles. We show that, in addition to replacing the facial neurons at peripheral synapses, a new short-latency trigemino-hypoglossal reflex, of the R1 blink reflex type, can be demonstrated in patients showing recovery, implying a sprouting of trigeminal neurons towards hypoglossal motoneurones, over a distance of at least 0.5 cm. These surprising results show an unexpected influence of the periphery in remodelling central connectivity in man.

Adult↗
PubMed1996

Botulinum toxin treatment in the facial muscles of humans: evidence of an action in untreated near muscles by peripheral local diffusion.

In a population of subjects with blepharospasm and facial hemispasm treated for the first time with botulinum toxin type A (BT) in the orbicularis oculi muscle, we performed an electrophysiologic study (compound muscle action potential and motor evoked potential) to assess whether BT effect could be detected in near untreated muscles (orbicularis oris and masseter). There was a significant BT action in nearly untreated muscles with different peripheral innervation that can be explained by local diffusion of the drug.

Action Potentials↗
PubMed1983

The utilization of EMG biofeedback for the treatment of periorbital facial muscle tension.

A case is presented of EMG feedback for reduction of tension in the orbicularis oculi muscle of both eyes. Feedback was provided for reduced firing of the upper and lower segments of the muscle. Within 25 sessions for the left eye and 20 sessions for the right, muscle output was markedly reduced from baseline and the patient reported no longer experiencing discomforting sensations of tightness. Follow-up of the patient 3 months posttreatment revealed that the initial problem of muscle tension no longer existed.

Adult↗
PubMed2003

Effects of immediate and delayed facial-facial nerve suture on rat facial muscle.

OBJECTIVE: To investigate regeneration of the mimic musculature after delayed facial nerve repair. MATERIALS AND METHOD: In 30 rats the facial nerve on the right side was resected and immediately repaired with an end-to-end anastomosis. The entire levator labii muscle was removed on the right side and histochemically and morphometrically analyzed at 7, 14, 21, 28, 90 and 180 days after immediate nerve repair. In a further 20 rats, reinnervation was performed after 4 weeks in a further operation and the muscle was assessed at 14, 28, 90 and 180 days. Seven muscles of four normal rats were used as controls. RESULTS: Three muscle fiber types could be identified by comparative histochemical analysis of two enzymes of succinate dehydrogenase (SDH) and m-ATPase: oxidative glycolytic (FOG) fibers, fast glycolytic (FG) fibers and intermediate muscle fibers that were designated SDH-INT. The number of fibers and the frequency distribution of single-fiber cross-sectional areas were determined for each type of fiber. No significant difference in the cross-sectional area of all fiber types was noted after 180 days when comparing immediate and delayed end-to-end sutures. In contrast, comparison of the fiber-type composition showed a significant increase in the number of FG fibers in the delayed suture, at the expense of FOG fibers. After immediate reinnervation the muscle approximately attained its natural fiber-type composition, whereas after delayed reinnervation the muscle showed an overall loss of oxidative capacity and differentiation towards phasic activity. CONCLUSION: Changes in fiber-type composition following delayed nerve suture are irreversible and have specific effects on the precise function of the muscle. Immediate nerve repair improves axonal reinnervation.

Animals↗
PubMed1990

Recordings from the facial nucleus in the rat: signs of abnormal facial muscle response.

On the basis of results of electrophysiological studies in patients undergoing microvascular decompression (MVD) operations to relieve hemifacial spasm (HFS), we have postulated that the abnormal muscle response characteristically found in patients with HFS is the result of irritation of the facial nerve by the blood vessel that is compressing the facial nerve near its exit from the brainstem in these patients. This abnormal muscle response is seen when one branch of the facial nerve is electrically stimulated and recordings are made from muscles that are innervated by other branches of the facial nerve. We further hypothesized that the facial nucleus is hyperactive in patients with HFS and that the spasm and the abnormal muscle response are results of a phenomenon known as "kindling". These hypotheses are supported by recent studies showing that chronic electrical stimulation of the facial nerve trunk in rats near the brainstem results in an abnormal muscle response that is similar to that seen in patients with HFS. In this paper, we present the results of recording from the facial motonucleus in rats that had been subjected to repeated electrical stimulation of the facial nerve. The results indicate that the abnormal muscle response in these rats was caused by changes in the function of the facial motonucleus. We interpret these results as showing that the physiological abnormalities that give rise to the signs of HFS in man are located in the facial motonucleus, and that the changes in the function of the nucleus are produced by chronic antidromic neutral activity resulting from close contact between a blood vessel and the facial nerve.

Animals↗