Object. The aim of this study was to describe six variations of the extreme-lateral craniocervical approach, their application, and treatment results. Methods. During a 4-year period 69 patients underwent surgery in which six variations of the extreme-lateral craniocervical approach were performed. The variations included: the transfacetal approach (TFA), performed to treat four lesions in the upper cervical spine anterior or anterolateral to the spinal cord; the retrocondylar approach, to treat five intradural lesions located anterolateral to the medulla oblongata and six vascular lesions to expose the extradural segment of the vertebral artery (VA); the partial transcondylar approach (PTCA), to treat 18 intradural lesions located anterior to the medulla oblongata; the complete transcondylar approach (CTCA), to treat 13 extradural lesions that involved the lower clivus and anterior upper cervical spine; the extreme-lateral transjugular approach, to treat 14 jugular foramen tumors; and the transtubercular approach with or without division of the sigmoid sinus, to treat complex VA and vertebrobasilar junction aneurysms. An anatomical prosection was performed to study the surgical exposure of each of the six variations of the extreme-lateral craniocervical approach. Total removal was achieved in 35 (69%) of the patients with tumor; subtotal resection was achieved in 16 (31%) of those patients. In the 12 patients with VA aneurysms, seven underwent clipping, three underwent trapping and a vein graft bypass procedure, and two underwent trapping without the use of a bypass procedure. In five other patients, different cystic, inflammatory, and other vascular lesions were successfully treated. Fifty percent of the patients who underwent surgery via the TFA, 83% via the of the CTCA, and 11% via the PTCA required an occipitocervical fusion procedure. The mean Karnofsky Performance Scale score was 74.7 preoperatively and 76.4 postoperatively. Major complications were hydrocephalus (nine patients), cerebrospinal fluid leakage (seven patients), worsened cranial nerve function (seven patients), vertebrobasilar vasospasm (one patient), and sigmoid sinus thrombosis (one patient). Conclusions. To treat lesions in the region of the foramen magnum and surrounding areas, the approach should be tailored to each specific lesion to provide the needed exposure without unnecessary operative steps.

Encephaloceles are pathological herniations of brain parenchyma through congenital or acquired osseus-dural defects of the skull base or cranial vault. Although encephaloceles are known as rare conditions, several surgical reports and clinical series focusing on spontaneous encephaloceles of the temporal lobe may be found in the otological, maxillofacial, radiological, and neurosurgical literature. A variety of symptoms such as occult or symptomatic CSF fistulas, recurrent meningitis, middle ear effusions or infections, conductive hearing loss, and medically intractable epilepsy have been described in patients harboring spontaneous encephaloceles of middle cranial fossa origin. Both open procedures and endoscopic techniques have been advocated for the treatment of such conditions. The authors discuss the pathogenesis, diagnostic assessment, and therapeutic management of spontaneous temporal lobe encephaloceles. Although diagnosis and treatment may differ on a case-by-case basis, review of the available literature suggests that spontaneous encephaloceles of middle cranial fossa origin are a more common pathology than previously believed. In particular, spontaneous cases of posteroinferior encephaloceles involving the tegmen tympani and the middle ear have been very well described in the medical literature.

One-hundred patients who had undergone decompressive surgery for lumbar stenosis between 1980 and 1985 were evaluated as to their long-term outcome. Four patients with postfusion stenosis were included. A 5-year follow-up period was achieved in 88 patients. The mean age was 67 years, and 80% were over 60 years of age. There was a high incidence of coexisting medical diseases, but the principal disability was lumbar stenosis with neurological involvement. Results were categorized as either a surgical success or a failure, depending upon the achievement of preset goals within the context of lifestyle and needs. There were no perioperative complications. Initially there was a high incidence of success, but recurrence of neurological involvement and persistence of low-back pain led to an increasing number of failures. By 5 years this number had reached 27% of the available population pool, suggesting that the failure rate could reach 50% within the projected life expectancies of most patients. Of the 26 failures, 16 were secondary to renewed neurological involvement, which occurred at new levels of stenosis in eight and recurrence of stenosis at operative levels in eight. Reoperation was successful in 12 of these 16 patients, but two required a third operation. The incidence of spondylolisthesis at 5 years was higher in the surgical failures (12 of 26 patients) than in the surgical successes (16 of 64). Spondylolisthetic stenosis tended to recur within a few years following decompression. To forestall recurrences, it is suggested that stabilization be carried out at levels of spondylolisthetic stenosis and the initial decompression include adjacent levels of threatening symptomatic stenosis. However, the heterogenicity of this patient population, with varying patterns and levels of symptomatic stenosis, precludes application of rigid surgical protocols.

Animal navigation studies have implicated structures in and around the hippocampal formation as crucial in performing path integration (a method of determining one's position by monitoring internally generated self-motion signals). Less is known about the role of these structures for human path integration. We tested path integration in patients who had undergone left or right medial temporal lobectomy as therapy for epilepsy. This procedure removed approximately 50% of the anterior portion of the hippocampus, as well as the amygdala and lateral temporal lobe. Participants attempted to walk without vision to a previously viewed target 2-6 m distant. Patients with right, but not left, hemisphere lesions exhibited both a decrease in the consistency of path integration and a systematic underregistration of linear displacement (and/or velocity) during walking. Moreover, the deficits were observable even when there were virtually no angular acceleration vestibular signals. The results suggest that structures in the medial temporal lobe participate in human path integration when individuals walk along linear paths and that this is so to a greater extent in right hemisphere structures than left. This information is relevant for future research investigating the neural substrates of navigation, not only in humans (e.g., functional neuroimaging and neuropsychological studies), but also in rodents and other animals.