Takanobu Kunihiro

Dynamic and static subjective visual vertical with aging

OBJECTIVE Our vestibular function is gradually deteriorating during aging, although, its behavioral consequences are not easily recognized due to a substitution process by other sensory modalities as visual or proprioceptive inputs. METHODS To reveal such a hidden substitution process by visual signals, the measurement of the static as well as the dynamic subjective visual vertical (SVV) was performed among 63 healthy subjects of different age. RESULTS The static SVV was found to be stable among all subjects, whereas the shift of the dynamic SVV during rotation of a background scene gradually increased with age. CONCLUSION This result indicates that the substitution process identified as a function of age in a perceptual test may have its counterpart in postural stabilizing reflex.

Perilymph fistula — 45 case analysis

PURPOSE OF THE STUDY Though perilymph fistula (PLF) is not a rare disease, preoperative diagnosis still remains to be established. Some new diagnostic methods are challenging, but there is still no established diagnostic method except exploratory tympanotomy that verifies the occurrence of leakage. Early diagnosis of PLF is fully depending on history taking and some clinical examinations. To know the clinical features of PLF is one of the greatest helps to make both earlier and accurate diagnosis. In spite of some innovations in clinical examinations classic diagnostic procedure is thought to be still reliable. PROCEDURES We investigated the clinical symptoms, basic tests results and therapeutic results in patients with PLF. RESULTS From 1983 to 1998 PLF was identified in 44 patients (45 ears) with exploratory tympanotomies in our hospital. With respect to clinical history the predisposing factors such as blowing the nose, lifting heavy goods, and landing in an airplane were found in almost half of the patients, while the rest of them had no clear inducing factors. Their major symptoms included hearing loss (93%), vertigo and dizziness (91%), tinnitus (76%), and aural fullness (31%). The patients who have a clear predisposing factor tended to make diagnosis easily; on the other hand the rest of the patients who do not have clear etiology had some diagnostic difficulty. Subjective positive fistula signs were observed in 71% of patients. Vestibular symptoms improved in 80% of patients after closure of PLF. CONCLUSIONS These results suggest that the variety of clinical manifestation make diagnosis more difficult. At the moment meticulous clinical history taking and close follow-up applying repeating fistula tests are the most important for not only earlier but also accurate diagnosis.

Connexin 26 distribution in gap junctions between melanocytes in the human vestibular dark cell area

We have previously demonstrated the presence of gap junctions between melanocytes in the human vestibular organ and have speculated that melanocytes function in maintaining the homeostasis of the microenvironment of the inner ear. The purpose of the present study was to characterize the expression and ultrastructural localization of connexin (Cx) protein in melanocytes of the human vestibular organs. Surgical material was obtained from patients operated on for vestibular schwannoma and was processed for light microscopy, confocal laser scanning microscopy, conventional TEM, and immuno TEM. The specimens were labeled with anti‐Cx26, Cx32, and Cx43 antibodies and examined by light microscopy. Specimens were also labeled with anti‐Cx26 antibody and examined by laser microscopy and immuno‐TEM methods. The specimens examined in this study were mainly dark cell areas from the human vestibular organ, whose epithelial and subepithelial layers are rich in melanocytes. Light‐microscopic immunohistochemical studies showed positive labeling for Cx26 protein between subepithelial melanocytes, and Cx32 was also detected. Use of anti‐Cx26 antibody and confocal laser scanning microscopy revealed high levels of Cx26 around the subepithelial melanocytes. Post‐embedding immuno‐gold transmission electron microscopy showed significant aggregation of gold particles (33.97 ± 8.01% of total gold particles) around the gap junctions of the subepithelial melanocytes. The results of this study indicated that melanocytes are connected through gap junctions that mainly contain Cx26. This suggested that the melanocytes in the human vestibular organ may play a role in transporting material between the endolymph and perilymph. Anat Rec 262:137–146, 2001.

Hypoglossal-facial Nerve Anastomosis Clinical Observation

We have reviewed 35 cases of hypoglossal-facial nerve anastomosis performed during the past 15 years for irreversible peripheral facial paralysis caused by surgery for acoustic neuroma. Of 27 patients who were followed more than 1 year after anastomosis, recovery of serviceable facial function was obtained in 25 (92.6%). Neural deficits secondary to transection of the hypoglossal-facial nerve were minimal or acceptable in most cases. The overall results were better in patients who underwent this procedure within 3 months after surgery for acoustic neuroma as compared with those who did so after 1 year or more. The 2 patients who underwent intracranial facial nerve reconstruction during surgery for acoustic neuroma and showed poor facial recovery have presented a challenge to our strategy in the treatment of such patients.

Hypoglossal-Facial Nerve Anastomosis after Acoustic Neuroma Resection: Influence of the Time of Anastomosis on Recovery of Facial Movement

Facial movement following hypoglossal-facial nerve anastomosis was investigated in 29 acoustic neuroma patients. The amount of facial movement was assessed using both the grading system of House and Brackmann and the revised grading scale of Yanagihara. The data were analyzed to determine the influence of the time elapsed between tumor resection and anastomosis upon recovery of facial movement. A slightly larger number of patients with delayed anastomosis (7-23 months) showed minimally poorer results than those with early anastomosis (within 3 months). However, these differences were not statistically significant. Moreover, there was no apparent relationship between the duration of facial nerve paralysis and the recovery of facial movement within either of these two groups. These results showed that hypoglossal-facial nerve anastomosis can be delayed up to 2 years following tumor resection with only minimal effect on the recovery of facial movement.

Compensatory changes in static and dynamic subjective visual vertical in patients following vestibular schwanoma surgery

OBJECTIVE Among patients with vestibular schwanoma (VS), vestibular function is nonhomogeneous, both before and after surgical removal of the VS. This paper reports investigations of neural changes, especially changes in the contribution of visual input to vestibular system integration, after VS surgery. METHODS We examined 33 patients who underwent VS surgery via a middle fossa approach. Static and dynamic subjective visual vertical (SVV) was measured once after surgery and compared to those measured in control subjects. SVVs were assessed using a paradigm requiring the subject to manually adjust an image of a bar to the perceived vertical alignment. SVVs were measured when the background was stationary or rotating. RESULTS In almost all patients, static SVV deviated toward the operated side. In VS subjects, the mean static SVV was 1.8+/-2.2 degrees; the amount of deviation in the dynamic SVV toward the operated side (11.7+/-8.3 degrees ) was significantly larger than that to the intact side (8.8+/-5.5 degrees ). In VS subjects, static SVV was correlated with dynamic SVV only in cases of bar adjustments toward the operated side (R=0.67, P<0.001), but not in cases of adjustments toward the intact, unoperated side. The axis of rotation was defined as the mean value of dynamic SVV for adjustments toward either side. There was only a weak correlation between the static SVV and the axis of rotation (R=0.31; P<0.05) in the control subjects. On the other hand, a more robust correlation between static SVV and axis of rotation was found (R=0.67, P<0.001) in VS subjects. There was no correlation between the static SVV and the deviation of dynamic SVV from static SVV for CCW and CW in control subjects. In contrast, there were significant correlations between static SVV and deviation of dynamic SVV from static SVV for adjustments made toward both operated (r=0.48, P<0.001) and intact sides (r=038, P<0.05). CONCLUSION It is assumed that the amount of deviation in static SVV reflects the individual level of compensation. In addition, increased visual dependency evoked a symmetrical bias of the dynamic SVV from the measures at initial SVV assessment (i.e. static SVV or the center of tilt). As a result, we conclude that the contribution of visual inputs had changed after surgery, while at the same time, each patient used their static SVV as their reference point for orientation.

Classic hypoglossal-facial nerve anastomosis after acoustic neuroma resection: A review of 46 cases

To clarify the factors contributing to patient satisfaction with facial movement after the classic hypoglossal-facial nerve anastomosis, we examined 46 such patients who consented to an interview and video-recording. No correlation was seen between the physician’s evaluation of returned function (according to Yanagihara’s 40-point scale and the grading system of House-Brackmann) and the scores (full marks: 100 points) the patients assigned to their own facial movements. Instead the scores that the patients assigned were closely related to subjective oral dysfunction, such as difficulty in masticating, articulating, and swallowing. Those scores did not correlate with eye-related functional deficits. These findings indicate that modified techniques to minimize the hypoglossal nerve deficit may enhance patient satisfaction without sacrificing recovery of facial movements.

Intracranial Reconstruction of the Facial Nerve Clinical observation

Nine cases of intracranial facial nerve reconstruction are reviewed in this paper. All patients underwent this procedure for severe injury or disruption of the facial nerve during surgery for acoustic neruroma through the modified extended middle cranial fossa approach (1). Satisfactory recovery of facial function was obtained in 4 patients. Three patients underwent hypoglossal-facial nerve anastomosis 1.3-1.5 years later for no or poor recovery of the facial function. One patient refused any further surgical treatment despite unsatisfactory recovery. The remaining 1 patient, during a telephone interview, stated that facial function had not returned at all 1 year and 5 months postoperatively. Although some degree of associated movement or mass movement was unavoidable, facial movement and mimetic facial expression were better in the patients with satisfactory recovery, as compared with those after hypoglossal-facial nerve anastomosis (2). Fibrin glue, which we used in the latest 3 cases instead of suture, seemed to possibly solve the technical difficulty in placing a suture. Facial function after intracranial reconstruction with fibrin glue was as good or better than that after repair by suturing.

Analysis of the Prognosis and the Recovery Process of Profound Facial Nerve Paralysis Secondary to Acoustic Neuroma Resection

The prognosis and the recovery process of facial nerve paralysis were reviewed in 74 patients who, despite preservation of nerve continuity, showed no facial movement after acoustic neuroma resection. In 50 or 67.6% of patients, facial movement recovered sufficiently so as not to require any reanimation procedures. However, no apparent sign of remission was observed for 7-49 months in the other 24 patients (32.4%), and hypoglossal-facial nerve anastomosis was performed in 20 of these patients. When remission was seen, the first sign of muscle movement appeared most frequently after 3-4 months but, in a small number of patients, it was also seen within 1.5 months or after 5-10 months. Based upon these results, the timing of reanimation procedures for facial nerve paralysis following acoustic neuroma resection is discussed.

Steroid-Responsive Sensorineural Hearing Loss Associated with Aortitis Syndrome

Five cases of sensorineural hearing loss associated with aortitis syndrome are presented, and their clinical features are discussed in detail. All patients were middle-aged females. Pure-tone audiometry revealed a high-tone gradual-loss type of configuration, and the recruitment phenomenon was proved to be positive in most cases. The degree of hearing loss correlated well with the erythrocyte sedimentation rate. However, the most remarkable clinical feature was that the hearing loss showed steroid responsiveness in all cases. Based on these clinical features, it was suggested that the steroid-responsive sensorineural hearing loss associated with this syndrome might not be an incidental accompanying symptom but rather one of the local manifestations of the disease arising from similar mechanisms as the systemic inflammatory process. Associated conductive disturbance is also discussed.