The combined supra- and infratentorial approach has been subdivided into three variations: the retrolabyrinthine technique (petrous bone resection with preservation of hearing); the translabyrinthine technique (greater petrous bone resection and sacrifice of hearing); and the transcochlear technique (maximum petrous drilling, sacrifice of hearing, and transposition of the facial nerve). These three variations maximize temporal bone drilling and therefore provide exquisite exposure of the clivus and petrous regions with minimal or no brain retraction. The superior petrosal sinus is always sacrificed and the tentorium completely cut. The sigmoid sinus can be transected or kept intact, depending on the venous drainage and the degree of exposure required. A series of 46 patients who underwent the combined approach is presented.

Essential tremor (ET) is increasingly thought to involve a heterogeneous group of patients, with some also exhibiting symptoms of Parkinson's disease (PD), including cognitive deficits. The goal of this study was to utilize a broad battery of neuropsychological measures to compare the cognitive function of 33 ET patients with that of 33 matched PD patients and 21 normal controls. Results indicated that the ET group performed significantly worse than controls across multiple cognitive domains, but performed remarkably similar to PD patients, consistent with frontosubcortical dysfunction.

This article reports the outcomes of 654 consecutive patients treated during a 4.5-year period. Patients had a microdiscectomy, a laminectomy plus microdiscectomy, or a decompressive laminectomy with a microdiscectomy. The causes of ruptured discs were lifting (31.4%), falls (10.2%), and sports (10.0%). Almost all patients had complained of leg pain (99%), and 79% had radicular pain in a dermatomal distribution. Thirty-three percent of the patients had been involved in industrial accidents, and 6% had legal claims pending during the surgical period. Almost 11% of the patients had complications, and there was one death caused by abdominal arterial bleeding. Patients were also rated according to the Prolo Functional-Economic Outcome Rating Scale to improve the ability to compare series in the future. Almost 80% of the patients had good outcomes as defined by scores on this scale of 8 (16.2%), 9 (33.2%), and 10 (26.9%). Several conclusions can be drawn from the results of this series: 1) most patients had good outcomes; 2) patients with nonindustrial injuries had better outcomes than did patients with industrial injuries; 3) professionals with legal concerns and laborers with industrial insurance had good outcomes; and 4) the Functional-Economic Outcome Rating Scale appears to be a useful tool for comparing different procedures more objectively and for comparing the outcomes across series.

Both standard spectral analysis and time-dependent phase correlation techniques were applied to 27 pairs of tremor-related single units in the globus pallidus internus (GPi) and EMG of patients with Parkinson's disease (PD) undergoing stereotactic neurosurgery. Over long time-scales (approximately 60 s), GPi tremor-related units were statistically coherent with restricted regions of the peripheral musculature displaying tremor. The distribution of pooled coherence across all pairs supports a classification of GPi cell/EMG oscillatory pairs into coherent or noncoherent. Analysis using approximately 2-s sliding windows shows that oscillatory activity in both GPi tremor units and muscles occurs intermittently over time. For brain/muscle pairs that are coherent, there is partial overlap in the times of oscillatory activity but, in most cases, no significant correlation between the times of oscillatory subepisodes in the two signals. Phase locking between coherent pairs occurs transiently; however, the phase delay is similar for different phase-locking subepisodes. Noncoherent pairs also show episodes of transient phase locking, but they occurred less frequently, and no preferred phase delay was seen across subepisodes. Tremor oscillations in pallidum and EMGs are punctuated by phase slips, which were classified as synchronizing or desynchronizing depending on their effect on phase locking. In coherent pairs, the incidence of synchronizing slips is higher than desynchronizing slips, whereas no significant difference was seen for noncoherent pairs. The results of this quantitative characterization of parkinsonian tremor provide a foundation for hypotheses about the structure and dynamical functioning of basal ganglia motor control networks involved in tremor generation.