Katsuya Ishido

Surgical control of akinesia in Parkinson's disease

Posteroventral pallidotomy (PVP) was carried out in 86 patients with Parkinsons disease, who presented marked bradykinesia, freezing of gait and postural defect associated with rigidity and tremor in 82 patients (bradykinesia type), and similar gait and postural problems with minimum signs of rigidity and tremor in 4 (pure akinesia type). The stereotactic coordinates of Leksells device were calculated from MRI and conventional ventriculography. The final target was defined by microelectrode techniques in the basal ganglia. The microrecording study revealed a very high background activity in the internal pallidum in patients of the bradykinetic type, however, a much lower pallidal activity in patients of the pure akinesia type. Fifty-eight patients underwent unilateral PVP, and 28 underwent bilateral surgery. Following PVP, rigidity tremor and poor reciprocal movements were significantly improved especially in the contralateral extremities. The most dramatic findings were the reversal of akinetic symptoms and wearing-off phenomena. The patients were followed up for 3-30 months (mean = 8) after surgery. Of the 82 bradykinesia type patients, good result were obtained in 48 (58%), fair results in 26 (32%), and minor improvement or no change in 8 (10%). In all the 4 patients of the pure akinesia type, recurrence of the akinetic symptoms occurred after a temporal improvement lasting a few days to 3 month after surgery. There was worst dysarthria in 3 patients, hemiparesis in 1 and partial motor aphasia in 1. The visual field problem was not complicated in any patients. These findings suggest that akinetic symptoms in PD are implicated in overactive pallidal outputs with putative GABAergic modulator by excessively inhibiting pedunculopontine nucleus activity (midbrain locomotor and posture regions) as well as thalamic activity. Partial interruption of the pallidal efferents eliminates the akinetic symptoms by disinhibitory effects on the target structures. The pathology of PD of the pure akinesia type is supposedly in the brainstem and should be excluded from indication of pallidotomy.

Tremor induced by toluene misuse successfully treated by a Vim thalamotomy

A 22 year old man developed a vigorous tremor of 5 Hz in his right hand, after a 7 year history of toluene misuse. T2 Weighted MRI depicted marked decreases in the signal intensity of the basal ganglia, red nucleus, and thalamus on both sides. The stereotactic coagulation of the left nucleus ventrointermedius (Vim) of the thalamus abolished the tremors in his right hand. This patient clearly exhibited the pathological involvement of rubral lesions in generation of a toluene induced tremor on MRI. Toluene induced tremor is an irreversible symptom which persists even after stopping toluene misuse, therefore in medically intractable cases, it should be positively treated by a Vim thalamotomy.

Visual evoked potentials in the vicinity of the optic tract during stereotactic pallidotomy

We recorded visual evoked responses in eight patients with Parkinsons disease, using a depth electrode either at or below the stereotactic target in the ventral part of the globus pallidus internus (GPi), which is located immediately dorsal to the optic tract. Simultaneously, scalp visual evoked potentials (VEPs) were also recorded from a mid-occipital electrode with a mid-frontal reference electrode. A black-and-white checkerboard pattern was phase reversed at 1 Hz; check size was 50 min of arc . Pallidal VEPs to full field stimulation showed an initial positive deflection, with a latency of about 50 ms (P50), followed by a negatively with a mean latency of 80 ms (N80). The mean onset latency of P50 was about 30 ms. P50 and N80 were limited to the ventralmost of the GPi and the ansa lenticularis. Left half field stimulation evoked responses in the right ansa lenticularis region while right half field stimulation did not, and vice versa. These potentials thus seemed to originate posterior to the optic chiasm. The scalp VEPs showed typical triphasic wave forms consisting of N75, P100 and N145. The location of the recording electrode in the ansa lenticularis region did not modify the scalp VEP. These results suggest that P50 and N80 are near-field potentials reflecting the compound action potentials from the optic tract. Therefore, N75 of the scalp VEPs may represent an initial response of the striate cortex but not of the lateral geniculate nucleus.

Inferior Temporal Sulcus as a Site of Corticotomy: Magnetic Resonance Imaging Analysis of Individual Sulcus Patterns

OBJECTIVE Transcortical approaches to the inferior horn often result in quadrant hemianopsia attributable to the injury to the optic radiation. The inferior temporal sulcus (ITS) has received little attention as an entrance point for the transsulcal approach. We used the method of detecting the ITS with magnetic resonance imaging (MRI) scans and investigated the sulcus pattern of ITS, its incidence rate, and the availability of the ITS to the corticotomy for selective amygdalohippocampectomy. METHODS The sulcus patterns of the ITS of 100 temporal lobes in 50 healthy individuals were classified according to the number of interruptions by gyral bridges, and the localization of the ITS was characterized in relation to the outer surface by means of the surface anatomy scan of MRI. RESULTS Most of the ITS was interrupted by one to three gyral bridges (0 bridges, 8%; one bridge, 27%: two bridges, 37%; three bridges, 20%; more than four bridges or no apparent ITS, 8%). When the ITS was present, it was located 15 mm above the orbitotragus line at a point 20 mm anterior to the tragus. The number of gyral bridges was significantly larger in the left temporal lobes than in the right temporal lobes, regardless of the sex of the subject. CONCLUSION The ITS was clearly identified in 72% of the temporal lobes by the oblique sagittal view of MRI scans; thus, in such cases, the ITS was considered to be a candidate for an entrance point of a small temporal corticotomy. The preoperative observation of the ITS in relation to the orbitotragus line by means of MRI may improve the planning of the transsulcal approaches to deeply seated mesial temporal lesions, such as hippocampal sclerosis.

Pleomorphic xanthoastrocytoma with predominantly exophytic growth: case report

Yasushi Miyagi, M.D., Ph.D.,* Satoshi O. Suzuki, M.D., Ph.D.,‡ Toru Iwaki, M.D., Ph.D.,‡ Fumio Shima, M.D., Ph.D.,§ Katsuya Ishido, M.D.,* Takehisa Araki, M.D., Ph.D.† and Kazufumi Kamikaseda, M.D., Ph.D.* *Departments of Neurosurgery and †Neurology, Kaizuka Hospital, Fukuoka, Japan; ‡Departments of Neuropathology and §Clinical Neurophysiology, Neurological Institute, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan

2902 Basal ganglia activity in movement disorders

Hitoshi Su~ukil~~~~, Koji Abe’, Mitinao Mizugaki3, Yasuto Itoyama’ P-selectin, which plays a pivotal role in the transmigration of white blood cells in the cerebral infarct, seems to be important in the pathogenesis of stroke. We investigated the change of immunoreactive P-selectin and HSP72, that is a marker of neuronal injury, in rat brains after transient MCA occlusion. Western blot analysis revealed induction of P-selectin at 12 h and of HSP72 at 24 h after blood flow restoration. Immunohistochemical analysis showed that endothelial cells in the ischemic cortex expressed immunoreactive P-selectin at Id of reperfusion, though it was induced 3d after reperfusion in the endothelial cells of striatum. On the other hand, HSP72 was induced at 8h after reperfusion, with a peak at Id in cerebral cortex and 3d in striatum.

2903 Mechanism of pallidal stimulation therapy for freezing of gait in parkinson's disease

FUMIO SHIMA, KATSUYA ISHIDO, MOTOHIRO KATO Freezing of gait in the patients with Parkinson’s disease (PD) is caused by damage of the structures essential for movements that are self-initiated, and self-guided, and it is well corrected by exteroceptive guidance as known as “paradoxical kinesia” . Posteroventral pallidotomy (PVP) alleviates dramatically bradykinesia, however, it often fails to improve the initial hesitation of gait. Sbjecting the PD patients with marked freezing and minimum signs of bradykinesia and rigidity, we made unilateral stimulation of the internal pallidum (GPi) giving high frequency pulses (120Hz, 0.2~s, l-2V). The deep stimulation therapy (DBS) improved dramatically the locomotion problems in most cases. Effective zone of DBS located anterodorsally to PVP region may connect to the supplementary motor area (SMA) via the thalamic nucleus, and high frequency stimulation of the pallidal zone elliminates freezing by activating the SMA bilaterally.

2902 The globus pallidus gives two outputs differing in somatotopic organization and developmental stage: A hypothesis based on experiences of stereotactic surgery for dystonia

Dystonia tends to generalize involving mainly in the trunk and proximal portion of the extremities in pediatric patients, while it often localizes in the face, neck and hand in adult patients. Previously, we described focal dystonia in adult patients was well controlled by VL thalamotomy. For treatment of dystonia with onset under 10 years of age (n=9), we carried out stereotactic VL thalamotomy in 8 patients and posteroventral pallidotomy (PVP) in 5. Thalamotomy lightened dystonia principally in the face, neck and hands, however, it failed to improve the main motor signs in the trunk and legs. PVP dramatically abolished the central dystonia in the most patients who had only a little benefit from tbalamotomy previously undergone. The surgical effects lasted for years without medical treatments. PVP is well known to alleviate gait and postural problems in Parkinson’s disease possibly by modifying function of the descending pallido-reticula-spinal pathway. Present findings suggest that pathogenesis of dystonia concerns with dysfunction of two pallidal pathway which organize different somatotopy and develop with time lag.