Stylomastoid Foramen Research Articles

Indication, technique and results of facial nerve reconstruction.

160 patients with various intra- or extracranial pathologies were treated by microsurgical facial nerve reconstruction at Nordstadt Neurosurgical Clinic between 1978 and 1993. Facial nerve reconstruction was accomplished along the anatomical course of the facial nerve from its origin at the brainstem, within the mastoid, at the stylomastoid foramen and within the face. Mostly, reconstruction was indicated because of nerve discontinuity (n = 61), whereas facial nerve reanimation with a donor nerve such as the contralateral facial nerve or the ipsilateral hypoglossal nerve was indicated in 99 cases of loss of a proximal nerve stump. Depending on the site of the lesion reinnervation started at 5 to 15 months postoperatively lasting for 2 to 3 years with overall satisfactory results. 69% of all the patients regained good symmetry on rest, complete eye closure equivalent to House-Brackmann-Score III: Patients with complete failures either suffered of non-related diseases such as cancer leading to death before the estimated time of recovery or were exposed to radiation or received facial nerve reconstruction after long-standing facial deficit and marked muscular atrophy. The indication of the adequate method depends on the clinical course with or without preexisting facial paresis, on considering the intraoperative state of the facial nerve, the identification and microsurgical preparation of adequate nerve stumps, as well as on the adaptation techniques and the postoperative guidance of the patient. We conclude that facial nerve reconstruction by transplantation at either site of the nerve course or by reanimation with a donor nerve are effective and reliable procedures of treatment leading to satisfactory functional and cosmetic results.

Effects of peripheral axotomy on presynaptic axon terminals with GABA‐like immunoreactivity

The facial nerve was unilaterally crushed at its exit from the stylomastoid foramen in three 3-month old male rats. After 10 days survival, before the regenerating axons had reinnervated their target muscles, the facial nucleus was examined to determine central patterns of response in material prepared to demonstrate the presence of GABA-like immunoreactivity with postembedding procedures using gold-labeled secondary antibody. The uninjured nucleus served as a control. In both control and injured nuclei, the GABAergic terminals synapse with all parts of the motor neurons, except the axon, and exhibit diverse morphologies. GABAergic axon terminals vary in their size and in the electron density of their axoplasm and the majority of the terminals contain pleomorphic vesicle profiles that display a range in their packing density and size. In both control and injured facial nuclei, only approximately 40% of the axon terminal profiles with pleomorphic vesicles exhibit GABA immunoreactivity. A morphometric analysis of the synaptic vesicle profiles in the GABA-positive terminals reveals that following axotomy there is no change in the mean number of synaptic vesicle profiles per GABAergic terminal profile. However, the mean size of the synaptic vesicle profiles in these terminals shows an axotomy-induced 50% increase, without change in the shapes of the enlarged vesicle profiles. Also, the numerical density of gold particles associated with the GABA-positive terminals is consistently greater in the injured than the control axon terminals. In the control animals quantitative analysis of the relative distribution of all axon terminal profiles in the neuropil categorized by the shape of their vesicle profiles as round, pleomorphic, or flat is 57:37:6. Ten days after axotomy the ratio of these categories in the injured nucleus has shifted to 35:60:5. This study demonstrates that the functional state of a postsynaptic target can influence the morphology of vesicle profiles in presynaptic elements as well as patterns of its afferent input.

Physical Facial Nerve Block in the Treatment of Hemifacial spasm

Hemifacial spasm consists of irregular, but repetitive clonic twitching of the muscles of one side of the face. Usually it is first involved around the eyes, the repetitive twitching spreads slowly to involve the whole face. It most commonly affects middle aged or elderly women, and usually appears with an aberrant vascular cross-compression near the root entry zone (REZ) of VII nerve. Among numerous approaches to treat facial spasm, only Jannetta's microvascular decompression has confirmed efficacy. However facial nerve block by needle insertion technique seems to be of benefit in patients with mild spasm, the elderly, poor risks and those who refuse the craniotomy. To treat our three patients with hemifacial spasm, we did physical facial nerve block by a direct puncture of the facial nerve trunk just at its exit from the stylomastoid foramen. Satisfactory results were obtained by the treatment employed. This technique is a valuable method in the treatment of hemifacial spasm.

Experimental study on antidromic evoked potential of the facial nerve for clinical application

Antidromic evoked potentials (AEPs) of the facial nerve were registered from the external auditory canal (EAC) of guinea pigs to clarify the origin of AEP and to compare diagnostic values of AEP with those of conventional evoked electromyography (eEMG). 1) The latency of AEP registered from EAC was compared with those from three points along the fallopian canal. The results showed that the latency from the pyramidal portion was almost equal to that from EAC. 2) AEPs were registered from EAC following sectioning of the intratemporal portion of the facial nerve at five points between the geniculate ganglion and the stylomastoid foramen. The waveform of the AEP was biphasic when the nerve was cut proximal to the pyramidal portion. It was monophasic when sectioned peripheral to that portion. These results, together with findings from experiment 1, indicate that AEP reflects the evoked potential generated around the pyramidal portion of the facial nerve, and that AEP is useful for the topodiagnosis of facial palsy. 3) AEP and eEMG were registered to assess changes in elicitability following compression of the facial nerve. Disappearance and reappearance of the AEP reflected well the function of the facial nerve as compared to the eEMG. This also indicates that AEP is a potentially sensitive and reliable diagnostic parameter for predicting the prognosis of facial palsy. 4) Registration of AEPs was attempted in three normal human subjects and in seven patients with Bell's palsy. AEP were recordable in all three normal men. Recording was however, possible in only two of seven patients on the involved side.(ABSTRACT TRUNCATED AT 250 WORDS)

Histopathological study of the recovery process in experimental facial nerve palsy induced by freezing

The facial nerve has a specific anatomical feature in that it pursues a relatively long course through a bony canal, originating in the fundus of the internal auditory meatus, until emerging at the stylomastoid foramen. Facial nerve palsy, which is often observed clinically, exhibits a high recovery rate of facial movement. There is no consensus, however, as to the influence of the anatomical features of the facial nerve on the pathological evolution of the palsy. The purpose of this study is to investigate how histological alterations, following injury of the nerve, are influenced by the anatomical feature mentioned above. Mongolian gerbils, weighing 60 g-90 g, were used. Facial nerve palsy was induced by freezing the tympanic part of the facial nerve. Myringotomy was then performed using microscope. The middle ear space was frozen at -2 degrees C to -8 degrees C for 30 seconds through perforation with dimethylether liquid propane gas. Facial nerve palsy was confirmed by loss of the blink reflex and whisker movement. Specimens were removed from the tympanic part of the facial nerve, embedded in epon, and the sections were examined under light and electron microscopy. Out of 16 ears (13 animals) thus frozen, 15 (94%) exhibited complete facial palsy. Facial movement recovered within the 21-to 35-day period after freezing. At thirty-six hours after freezing, thin regenerating axons were seen in Schwann cell basal lamina scaffolds. Even on the seventh day after freezing, when connective tissue around the nerve trunk was thickest, regenerating axons continued to grow and did not degenerate.(ABSTRACT TRUNCATED AT 250 WORDS)

Total Facial Nerve Decompression for Restoration of Facial Palsy Associated with Temporal Bone Fracture

For restoration of facial palsy associated with temporal bone fracture, decompression of the facial nerve between the lesion and the stylomastoid foramen is reliable surgical treatment and valuable to minimize residual palsy and sequela such as synkinesis and contracure of the face. When the fracture involves the geniculate ganglion and its vicinity, a total decompression of the intratemporal facial nerve from the internal auditory canal to the stylomastoid foramen is required. Two surgical approaches, translabyrinthine approach and combined middle fossatransmastoid approach, are available for the total decompression. Surgical techniques in these two approaches are described in detail together with indication for each approach, surgical complications and the results.

Facial nerve near the external auditory meatus in man: computer reconstruction study--preliminary report.

The anatomy of the facial nerve relative to its intratemporal and extratemporal courses varies over time with developmental changes. Otologic and parotid surgery in infants and children demands detailed knowledge of the precise anatomy of the facial nerve with respect to the tympanic ring and external auditory canal. The authors analyzed this area using our three-dimensional (3-D) computer-aided reconstruction and measurement method studying the spatial relations of the facial nerve to the tympanic ring and stylomastoid foramen. Temporal bones from five normal individuals aged 36 gestational weeks, 3 months, 8 months, 4 years, and 17 years were retrieved from the temporal bone collection stored at the Elizabeth McCullough Knowles Otopathology Laboratory in Pittsburgh. Three-dimensional reconstruction of the facial nerve comparing the developmental anatomy across the various age groups provides the surgeon with the technical information necessary to address problems in this area.

Motor evoked potentials from magnetic stimulation of dorsal spinal roots

The facial nerve (CN VII) emerges from the facial nerve nucleus in the pons. It is accompanied by CN VIII along its cisternal pathway, as well as at the internal auditory meatus. Its petrous pathway includes a labyrinthine segment, a horizontal tympanic segment and a vertical mastoid segment until the stylomastoid foramen. It then continues to the parotid gland. Pontine impairment is usually associated with other neurological symptoms. Lesions of the cerebellopontine angle (most often meningioma and schwannoma) initially result in impairment of CN VIII. The impairment of CN VII takes second place. Peripheral impairment (outside of a traumatic context) is most often due to Bell's palsy.

Facial nerve hypofunction in hemifacial spasm patients

The facial nerve (CN VII) emerges from the facial nerve nucleus in the pons. It is accompanied by CN VIII along its cisternal pathway, as well as at the internal auditory meatus. Its petrous pathway includes a labyrinthine segment, a horizontal tympanic segment and a vertical mastoid segment until the stylomastoid foramen. It then continues to the parotid gland. Pontine impairment is usually associated with other neurological symptoms. Lesions of the cerebellopontine angle (most often meningioma and schwannoma) initially result in impairment of CN VIII. The impairment of CN VII takes second place. Peripheral impairment (outside of a traumatic context) is most often due to Bell's palsy.

Audiological study in guinea pigs with type I allergy induced in the inner ear.

Time course studies of electrocochleography and the auditory brain stem response were performed in guinea pigs that were passively sensitized by sera containing antidinitrophenyl reaginic antibody and specifically challenged by dinitrophenyl-bovine serum albumin injected through the stylomastoid foramen. A negative summating potential on electrocochleography was observed from 12 to 48 hours, but not at 72 hours, after the specific challenge. A threshold increase on the auditory brain stem response was observed 15 minutes after the specific challenge; the threshold recovered to the prechallenge level within 7 days. Further, we used Tranilast, a blocking agent of chemical mediator release from mast cells, before the specific challenge. A negative summating potential and head deviation were not observed after the use of this agent. These results suggest that the auditory change provoked in the inner ear of the sensitized guinea pig may have been induced by type I allergy.

Mental health in children

Summary: We present five cases of intraparotid facial nerve schwannoma. In four of the five cases, tumors arising from the main facial nerve trunk were centered just below the skull base near the stylomastoid foramen and had a small cranial extension into the lower facial nerve canal. In three cases, each tumor had higher signal intensity around the periphery on T2-weighted images (target sign). These findings may be highly suggestive of an intraparotid facial nerve schwannoma.

Recovery from Facial Paralysis Following Crush Injury of the Facial Nerve in Hamsters: Differential Effects of Gender and Androgen Exposure

In recent studies, we have shown that administration of androgens to male hamsters enhances functional recovery from facial paralysis induced by facial nerve crush at the level of the stylomastoid foramen. Furthermore, we have established that the mechanism behind this enhancement of regeneration involves an acceleration of the rate of regeneration, without a shortening in the delay of sprout formation. From those studies, several unexpected findings of inherent sex differences emerged. First, intact (nongonadectomized) females have a faster facial nerve regeneration rate than males and, second, testosterone has a less dramatic effect on the rate of regeneration in females compared to males. In the present study, we explored these novel findings of sex differences in the response of motor neurons to injury. Adult intact female hamsters were subjected to right facial nerve crush axotomy at the level of stylomastoid foramen and either implanted with two or four silastic capsules containing 5α-dihydrotestosterone, or sham-implanted for controls. A group of adult intact male hamsters was also subjected to right facial nerve crush axotomy. Animals were observed daily, beginning on Day 1 postoperatively and continuing throughout a 3-week recovery period for signs of functional recovery from facial paralysis. The average day of return of each of four behavioral components (semi-blink, blink reflex, full vibrissae movement, and complete recovery) was calculated for all four experimental groups. The results indicate that intact females recover functional return of movement following crush injury significantly faster than intact males. In contrast to our previous findings in male hamsters, administration of exogenous steroids does not accelerate recovery from facial paralysis in adult female hamsters. Why these sex differences in both inherent recovery from peripheral nerve injury and in the ability of androgens to augment regeneration occur is unknown, but will be interesting to explore from a molecular perspective in future studies.

Testosterone enhancement of the nerve cell body response to injury: evidence using in situ hybridization and ribosomal DNA probes

In axotomized peripheral motoneurons capable of successful regeneration, one of the earliest morphological indicators of the injury response occurs within the nucleolus. In the initial part of this investigation, we mapped the nucleolar response of injured adult hamster facial motoneurons from a molecular perspective, utilizing in situ hybridization and ribosomal DNA probes complementary to stable rRNA. Recently, we have discovered that the gonadal steroid, testosterone propionate (TP), accelerates recovery from facial paralysis in the hamster by increasing the rate of regeneration of the fastest regrowing axons. In the second part of this study, the hypothesis that TP accomplishes these effects on facial nerve regeneration through an enhancement of the nerve cell body response to injury was tested using in situ hybridization and rDNA probes. Adult intact male hamsters were subjected to right facial nerve axotomies at the stylomastoid foramen. One-half of the axotomized animals received subcutaneous implants of TP, with the remainder sham implanted. In situ hybridization with tritiated rDNA probes was accomplished and levels of hybridizable rRNA assessed both qualitatively and quantitatively. Axotomy alone induced an upregulation in rRNA levels, with peak changes occurring by 24 hr postoperative and continuing through postoperative day 4. These molecular changes in the nucleolar response preceded, by a full day, any morphological signs of the nucleolar reactive pattern previously found in this cell type, and, as such, point to the usefulness of in situ hybridization as a tool to identify the earliest events associated with the axon reaction. A secondary smaller increase in rRNA levels was observed during the later stages of regeneration. TP significantly augmented the ribosomal response to injury, with levels of rRNA increased as early as 6 hr and the magnitude of the response greater than that occurring following axotomy alone. These results provide the first mechanistic step in the identification of the cellular processes underlying gonadal steroid augmentation of neuronal reparative processes. We conclude that TP accelerates the "switch" from a normal to a reparative state and suggest that this priming effect may be causally related to the differential effects of TP on the regenerative properties of this cell type.

Fazialisparese bei gutartigem Parotistumor: Fallbeschreibung und Literaturübersicht

Generally, typical symptoms are significant for malignant parotid tumours: The infiltration of surrounding structures and facial paralysis. A case is reported where a benign parotid tumour (lymphadenitis) caused facial paralysis. Parotidectomy and the removal of the lymph node near the stylomastoid foramen led to complete restitution. A review of the literature of the past 40 years mentions 16 cases of benign neoplasms of the parotid gland that caused facial paralysis, such as pleomorphic adenoma, Warthin's tumour, oncocytoma, benign parotid cysts, chronic parotitis, lymphadenitis and parotid abscess.

Magnetic stimulation of the facial nerve

Intracranial activation of the facial nerve and the face-associated motor cortex are now possible with noninvasive magnetic stimulation techniques. Compound muscle action potentials (CMAPs) and the Blink reflex, in response to magnetic stimulation, were investigated. Subjects were 10 normal controls and 2 Bell's palsy patients. CMAPs were elicited in the orbicularis oris muscle by magnetic stimulation at the parieto-occipital skull and stylomastoid foramen. Furthermore, CMAPs were evoked by a magnetic coil oriented over the cortex. CMAP recording was possible with magnetic stimulation and the latencies of CMAPs at the parieto-occipital skull were slightly greater than those at the stylomastoid foramen. In 10 normal subjects, the mean onset latency following transcranial magnetic stimulation of the facial nerve at the parieto-occipital skull was 5.07 msec (SD = 0.40), while transcutaneous latency at the stylomastoid foramen was 2.77msec (SD = 0.539). In the blink reflex, R1 latency was 10.99 msec (SD = 1.27), ipsilateral-R2 latency was 37.46 msec (SD = 2.57), and contralateral-R2 latency was 38.925 msec (SD = 3.20). The blink reflex thus had a configuration similar to that evoked by conventional electrical stimulation. In the patients with Bell's palsy, CMAPs elicited by magnetic stimulation were of low amplitude with normal latency. However, in the blink reflex, only a contralateral R2 response could be recorded, and R1 and ipsilateral-R2 showed no response to stimulation at the affected side. Investigation of patients with Bell's palsy using this technique may therefore prove useful in the evaluation of peripheral facial nerve disorders.

Large and small coils in magnetic stimulation of the proximal portion of the facial nerve.

Magnetic stimulation (Magstim model 200) was performed with a large coil (14 cm in diameter) and a small coil (7 cm in diameter) in 12 healthy persons. Muscle potentials were obtained from ipsilateral orbicularis oris and nasalis muscles when magnetic stimulation was performed by placing a large or small magnetic coil at T6 or by placing a large magnetic coil at C4. The latency obtained by placing a magnetic coil at T6 was 1.2-1.3 ms (with a large coil) and 1.3-1.4 ms (with a small coil) longer, and the latency obtained by placing a large magnetic coil at C4 was 1.3-1.4 ms longer than the latencies obtained by stimulating at the stylomastoid foramen. The proximal portion of the facial nerve is considered to be stimulated transcranially when magnetic stimulation is performed by placing either a large or small coil at T6 or by placing a large coil at C4.

Neuromas of the facial nerve: a report of 12 cases.

Twelve patients with facial nerve neurinoma have been treated at The National Hospital, Queen Square, London, during the last 20 years. Nine tumours lay in the middle fossa arising from the area of the geniculate ganglion, two lay in the posterior fossa arising from the segment of the facial nerve in the internal auditory canal, and one tumour arose from the vertical segment of the facial nerve with extracranial extension through the stylomastoid foramen. Two patients had neurofibromatosis. The clinical and radiographic features of those tumours, the operative approaches employed, and the postoperative outcome are described. Complete tumour excision was achieved in all patients; all 12 remain free of recurrence 3-80 months after surgery. Facial nerve function was restored at least in part in all cases by transposition with end-to-end anastomosis, placement of a cable graft from the sural nerve or hypoglosso-facial anastomosis. The major determinant of the outcome of facial nerve function was the duration of preoperative facial paralysis, the results being invariably poor when this was of long duration.

Funicular structure and nerve fiber topography in the extratemporal facial nerve of the guinea pig

The intratemporal portion of the facial nerve has a single bundle, while the extratemporal portion has multiple funiculi. In the guinea pig, the funiculi repeatedly divide and fuse between the stylomastoid foramen and the origin of the inferior labial branch. It remains unknown whether the nerve fibers in each funiculus are topographically organized or not. In this paper, the topographic organization of nerve fibers in a funiculus was clarified in the extratemporal facial nerve trunk of the guinea pig using an anterograde nerve degeneration technique. The author developed a technique in which one funiculus is cut selectively proximal to the origin of the cervical branch or peripheral to the origin of the inferior labial branch using microscissors under an operation microscope. Four to six days after sectioning, the main trunk just peripheral to the sectioned site was examined with toluidine blue staining to confirm that the resultant degeneration was limited to only one funiculus. Then all six main peripheral branches were sectioned and the distribution of degenerated nerve fibers in each branch was examined with toluidine blue staining. In six out of eleven nerves sectioned just proximal to the origin of the cervical branch, the degenerated nerve fibers were localized in one main peripheral branch. In the remaining five nerves, the degenerated nerve fibers spread into two or three main peripheral branches. In all nerves sectioned just peripheral to the origin of the inferior labial branch, the degenerated nerve fibers were localized in only one main peripheral branch, even though they distributed to several funiculi in the same branch.(ABSTRACT TRUNCATED AT 250 WORDS)

顔面神経磁気刺激検査 有用性についての検討

Magnetic stimulation of the peripheral facial nerve with Magstim model 200 was performed in normal human subjects without any history of facial nerve disorders. Contractions of the orbicularis oris and the orbicularis oculi muscles were evoked by magnetic stimulation around the auricle and were compared with those produced by extratemporal electrical stimulation.1) Infra-auricular stimulation with Magstim caused configurations and latency similar to those caused by electrical stimulation at the stylomastoid foramen.2) Contralateral stimulation of any site around the auricle never induced motor evoked potentials of both muscles.3) Changing the site of stimulation from the supra-auricular to the infra-auricular area tended to shorten the latency period.4) Ipsilateral stimulation of the right and left sides resulted in different latencies.Thus, the site of excitation was not defined clearly. We conclude that it is too early to use this method to diagnose conduction block of the facial nerve.

Electron microscopic nerve fiber caliber analysis in the nerve branches to the M. mylohyoideus in mouse.

Nerve fiber counts and caliber analysis of the nerve branches to m. mylohyoideus were performed with an electron microscope on 5 sides from 3 mice. The nerve branches contained an average of 93.6 (54.7%) myelinated fibers, 76.2 (44.6%) unmyelinated fibers and 1.7 (0.7%) undetermined fibers. 60.3% of the myelin sheaths of the myelinated fibers in the nerve branches were 3.5-6.0 microns in major diameter and 67.8% were 2.5-5.0 microns in minor diameter. 81.7% of the axons of the myelinated fibers were 1.5-4.5 microns in major diameter and 83.1% were 1.0-3.5 microns in minor diameter. The diameter frequency distributions of the myelin sheaths and axons of myelinated fibers in the nerve branches were similar in pattern to that of the facial trunk distal to the stylomastoid foramen. On the other hand, these frequency distributions of the nerve branches showed that the diameters of the myelinated fibers of the nerve branches were approximately 1-2 microns smaller than those of the r. digastricus, r. stylohyoideus and the nerve branch to venter rostralis of m. digastricus. Average ratios of the cross-sectional areas of myelin sheaths to those of axons of the myelinated fibers in the various axon area classes were 0.59-1.18, and those ratios tended to decrease in the larger axon classes.