Takashi Tsubuku

Downbeat positioning nystagmus is a common clinical feature despite variable phenotypes in an FHM1 family

Clinical examinations and mutational analyses were carried out in three patients of a Japanese familial hemiplegic migraine (FHM) pedigree. Each affected member demonstrated a broad clinical spectrum that included hemiplegic migraine with progressive cerebellar ataxia, migraine without aura, and episodic ataxia. Despite this variability, all members exhibited marked downbeat positioning nystagmus, and magnetic resonance images (MRI) all showed cerebellar atrophy predominantly of the cerebellar vermis. All affected members had a T666M missense mutation in the protein encoded by the CACNA1A gene (calcium channel, voltage-dependent, P/Q type, alpha 1A subunit). Although clinical features associated with the T666M CACNA1A mutation are highly variable, downbeat positioning nystagmus may be an important clinical feature of this disease.

Parotidectomy by U-shaped SkinIncision for small Benign Tumors

Parotidectomy by U-shaped Skin Incision for small Benign Tumors Objectives: The facelift incision has been used as a more cosmetically favorable alternative to the traditional cervicofacial, S-shaped incision for parotidectomy. However, the facelift incision has the disadvantage of requiring a long skin incision and wide skin-flap elevation. As an alternative, we analyzed the application and safety of a more limited U-shaped skin incision for parotidectomy. Methods: A U-shaped incision, consisting of pre- and postauricular incisions and a curved incision around the earlobe, was applied in 28 female patients. Their tumors were located in the superficial region of the parotid gland except one patient with a deep lobe tumor. Maximum diameter of the tumor was <3 cm. As a control, 18 patients with a S-shaped incision, who had superficial tumors <3 cm in diameter, were selected. Operative time and postoperative complications were retrospectively compared between the two incision approaches. Results: No significant difference in operative time was observed between U-shaped incision and S-shaped incision. The frequencies of temporary facial paralysis and salivary fistula were comparable between the two surgical methods. Conclusion: The U-shaped incision approach is feasible for parotidectomy in patients with small (<3 cm) benign tumors located in the superficial region of the parotid gland.

Impairments in Estimation of Target Velocity in SCA 6

Objective: Perception during visual motion is a fundamental function for the equilibrium system. Neural substrates for these systems are still incompletely known. We examined the role of cerebellum for those systems in Spinocerebellar ataxia type 6 patients. Method: Seven SCA6 patients and 7 age-matched normal controls participated in this study. Two tasks were tested. Task 1 examined subjects’ ability to estimate the timing of a target movement indicated by a finger movement. Task 2 examined the ability to match the remembered velocity of visual pattern movement. Results: In Task 1, when the target was always visible, the difference between the 2 groups was not significant at 2°/s and 5°/s of target movement. At 8°/s, there was significant difference between them. During the 50% target blanking condition, the patients showed lower successful ratios at 5°/s and 8°/s, respectively. In Task 2, when both subject groups fixated a stationary spot, there was no significant difference between the two groups at 2°/s and 5°/s. However, at 8°/s, the difference was significant. When a fixation spot was not presented, the difference was significant at all three velocities. Conclusion: Most SCA6 patients exhibited a larger variability in their timing estimation, and their estimations significantly lagged compared with controls. The present findings shed light on the mechanisms of estimation of target velocity and timing of movement initiation and support the conclusion that the cerebellum is involved in these functions.

Analysis of Floccular Purkinje (P-) Cell Discharge during 3D Pursuit

We investigated the spatial distribution of simple-spike response types of Purkinje cells (P-cells) within the cerebellar nodulus and uvula during sinusoidal head rotation in vertical plane in awake cats. Cells demonstrating the strongest response to the roll plane tended to be located in a parasagittal band extending more than 1.0 mm lateral to the midline, while those with the strongest response to pitch plane tended to be located in a band extending up to 1.0 mm from the midline. These findings suggest that there are at least 2 sagittal functional zones with a rostrocaudal extent in the search area examined in the present study. Such spatial information might be transmitted to the brainstem nuclei to control motor dynamics for the optokinetic responses under head-tilt conditions in each specific plane.

P109: Eye, Head, and Gaze Movement during Gaze Pursuit in SCA6

ing and circumferential crimping. CONCLUSIONS: The use of the smart self-crimping shape-memory Nitinol stapes piston provides more consistent piston positioning and crimping force. Use of the smart self-crimping shape-memory Nitinol stapes piston eliminates the drawbacks of manual crimping in stapedotomy and provides a technical simplification of the stapedotomy procedure in patients with otosclerosis. This should reduce stapes prosthesis loosening, displacement and incus erosion and allow for more reliable and consistent hearing results.