Segment Of Facial Nerve Research Articles

Degenerative changes in the distal stump of the severed human facial nerve.

Specimens of distal segments of the human facial nerve obtained at reinnervation surgery (hypoglossal-facial anastomosis) were studied by light and electron microscopy. Severance of the facial nerve led to the Wallerian degeneration in the distal segment. When the lesion was made at the intracranial level of the nerve, the sensory bundle remained intact. In a specimen 17 days after section, motor fibers either had disappeared or had loss of axons and advanced stage of myelin breakdown. Sensory fibers appeared intact. In two specimens three months after severance, many Schwann cells of degenerated fibers still possessed degraded myelin; most Schwann cells had ingested myelin and formed endoneurial tubes (bands of Büngner). Endoneurium showed proliferation of fibroblasts and increased collagen deposition. A specimen obtained seven months after section showed fibrosis only. The fifth specimen obtained 30 months after severance of the tympanic segment showed only mild collagenization and well formed, not appreciably shrunken Schwann tubes. The distal stump of human facial nerve appears to undergo less denervation atrophy than demonstrated in the peripheral nerves of experimental animals. The collagenization process appears to be essentially completed already after three months denervation with little change after that. The distal stump of the human facial nerve appears to provide a good structural basis for reinnervation even after prolonged denervation.

Hypoglossal-Facial Nerve Anastomosis for Reinnervation of the Paralyzed Face

The hypoglossal-facial nerve crossover is a valuable surgical procedure for the treatment of certain types of facial paralysis. It is most effective when used as an integral part of a primary ablative operation for the treatment of cancer in this region. In the treatment of long-standing facial paralysis, its application requires an intact peripheral facial nerve system and some functioning mimetic muscles with an obliterated proximal facial nerve segment. It is recognized that other procedures are available for repair in patients who meet essentially these same criteria. The disadvantages are minimal intraoral crippling, mass movements of the face and, in some instances, hypertonia of the face. The advantages are improved facial tone, protection of the eye, intentional facial movements controlled by the tongue, and movements associated with physiological functions of the tongue.

Facial rehabilitation with temporal muscle. New concepts.

Facial rehabilitation, utilizing the transposed temporalis muscle, was performed. Three new innovations of this technique include: (1) The whole muscle is transposed into the face to accomplish augmentation, support, protection for the eye, and movement. (2) Following transposition of the temporalis muscle, its nerve supply is lysed at the foramen ovale. Nerve substitution by a free, autogenous graft from the proximal segment of the ipsilateral facial nerve or crossfacial sural nerve is accomplished. This technique substitutes the facial nerve axons and nuclei for the trigeminal nerve in this muscle and thus eliminates movement on mastication and facilitates the possibility for expression. (3) This muscle may be transposed with a portion of the temporal and parietal bones to add bony architecture to the cheek and orbit.

Stereotaxic trigeminal tractotomy for post-herpetic facial pain.

✓ The development of accurate techniques for spinal stereotaxic surgery facilitates the difficult management of post-herpetic facial pain by making possible destruction of both the spinal trigeminal nucleus and descending tract; it also elminates excitation from the nuclear overlap between cervical and facial segments and intranuclear pathways. The technique is described and three cases reported. Stereotaxic trigeminal tractotomy relieves both the hyperpathia and deep background pain of herpes.

Experiments on the restoration of paralysed muscles by means by means of nerve anastomosis

Restoration of voluntary co-ordinated movements after “nerve crossing,” first demonstrated by Flourens, has since been from time to time the subject of investigation. The conclusions of Flourens have been confirmed by Rawa, Stefani, Howell and Huber, Langley, and myself. A practical application in surgery was first suggested by Letievant, and within the past 12 years considerable development has taken place in this direction. During the past two years I have performed about 30 experiments on monkeys and dogs in order to investigate several points from the physiological standpoint. These experiments fall naturally into three groups. The first deals with the methods of cross union or anastomosis between the peripheral segment of a divided facial nerve and a suitable motor nerve in the neighbourhood. The second series of experiments deals with anastomosis in the fore limb of dogs, in order to investigate some aspects of the question not overtaken by previous work on this part of the subject. The third series deals with the brachial plexus, its functions, and the methods of anastomosis applied to it. The present communication is confined to an account of experiments with the facial nerve, of which there have been 10 performed. Of these 10, 6 were primary anastomosis and 4 secondary anastomosis, that is to say, in 6 the facial was cut, and its peripheral segment immediately anastomosed with the central segment of the substitute nerve, while in 4 the facial was cut, and left unattached for a period, precautions to prevent spontaneous reunion being taken, and then at the end of that period re-exposed, and united to the substitute nerve.

EXPERIMENTS ON THE RESTORATION OF PARALYSED MUSCLES BY MEANS OF NERVE ANASTOMOSIS

Restoration of voluntary co-ordinated movements after “nerve crossing,” first demonstrated by Flourens, has since been from time to time the subject of investigation. The conclusions of Flourens have been confirmed by Rawa, Stefani, Howell and Huber, Langley, and myself. A practical application in surgery was first suggested by Letievant, and within the past 12 years considerable development has taken place in this direction. During the past two years I have performed about 30 experiments on monkeys and dogs in order to investigate several points from the physiological standpoint. These experiments fall naturally into three groups. The first deals with the methods of cross union or anastomosis between the peripheral segment of a divided facial nerve and a suitable motor nerve in the neighbourhood. The second series of experiments deals with anastomosis in the fore limb of dogs, in order to investigate some aspects of the question not overtaken by previous work on this part of the subject. The third series deals with the brachial plexus, its functions, and the methods of anastomosis applied to it. The present communication is confined to an account of experiments with the facial nerve, of which there have been 10 performed. Of these 10, 6 were primary anastomosis and 4 secondary anastomosis, that is to say, in 6 the facial was cut, and its peripheral segment immediately anastomosed with the central segment of the substitute nerve, while in 4 the facial was cut, and left unattached for a period, precautions to prevent spontaneous reunion being taken, and then at the end of that period re-exposed, and united to the substitute nerve.