The subthalamic nucleus (STN) has been regarded as an important modulator of basal ganglia output. It receives its major afferents from the cerebral cortex, thalamus, globus pallidus externus and brainstem, and projects mainly to both segments of the globus pallidus, substantia nigra, striatum and brainstem. The STN is essentially composed of projection glutamatergic neurons. Lesions of the STN induce choreiform abnormal movements and ballism on the contralateral side of the body. In animal models of Parkinson's disease this nucleus may be dysfunctional and neurons may fire in oscillatory patterns that can be closely related to tremor. Both STN lesions and high frequency stimulation ameliorate the major motor symptoms of parkinsonism in humans and animal models of Parkinson's disease and reverse certain electrophysiological and metabolic consequences of dopamine depletion. These new findings have led to a renewed interest in the STN. The aim of the present article is to review briefly the major anatomical, pharmacological and physiological aspects of the STN, as well as its involvement in the pathophysiology and treatment of Parkinson's disease.

Object Anterior cervical discectomy (ACD), ACD with interbody fusion (ACDF), ACDF with placement of an anterior plate system (ACDFP), corpectomy, and corpectomy with plate placement are used to fuse the cervical spine. The authors conducted a metaanalysis of studies published after 1990 in which fusion rates achieved with each procedure were reported for patients with degenerative disease at one, two, and three disc levels. Methods Twenty-one papers each included data on at least 25 patients. In each of the 21 studies the average clinical follow up was more than 12 months, and the results were evaluated according to radiographic evidence of fusion and delineated by the number of levels fused. Chi-square and Fisher exact tests were used for comparisons. The mean age of the patients was 46.7 years, 46.6% were female, and the mean follow-up period was 39.6 months. The studies included 2682 patients and the overall fusion rate was 89.5%. For single disc–level disease, fusion rates were 84.9% for ACD, 92.1% for ACDF, and 97.1% for ACDFP (p = 0.0002). For two disc–level disease, fusion rates were 79.9% for ACDF, 94.6% for ACDFP, 95.9% for corpectomy, and 92.9% for corpectomy with plate placement (p = 0.0001). For three disc–level disease, fusion rates were 65.0% for ACDF, 82.5% for ACDFP, 89.8% for corpectomy, and 96.2% for corpectomy with plate placement (p = 0.0001). The use of anterior plates significantly improved fusion for one-level (p < 0.0001), two-level (p < 0.0001), and three-level (p < 0.05) ACDF. There was no significant difference in fusion rates between two-level ACDF and corpectomy with plate placement. Conclusions The anticipated fusion rate is one of several factors that may guide surgical decision making. Anterior cervical decompression and fusion results in high fusion rates. The results of the authors' study show that regardless of the number of levels fused, the use of an anterior cervical plate system significantly increases the fusion rate. For two-disc–level disease, there was no significant difference between ACD with a plate system or corpectomy with a plate system. For three-disc–level disease, however, the evidence suggests that corpectomy with plate placement is associated with higher fusion rates than discectomy with plate placement.

BackgroundPreliminary clinical studies on the safety and efficacy of the pipeline embolization device (PED) for the treatment of small/medium aneurysms have demonstrated high occlusion rates with low complications.ObjectiveTo evaluate the safety and effectiveness of the PED for treatment of wide necked small and medium intracranial aneurysms.MethodsPREMIER is a prospective, multicenter, single arm trial. Patients were treated with the PED for unruptured wide necked aneurysms, measuring ≤12 mm along the internal carotid artery or vertebral artery, between July 2014 and November 2015. At 1 year post-procedure, the primary effectiveness endpoint was complete occlusion (Raymond grade 1) without major parent vessel stenosis (≤50%) or retreatment, and the primary safety endpoint was major stroke in the territory supplied by the treated artery or neurologic death.ResultsA total of 141 patients were treated with PEDs (mean age 54.6±11.3 years, 87.9% (124/141) women). Mean aneurysm size was 5.0±1.92 mm, and 84.4% (119/141) measured <7 mm. PED placement was successful in 99.3% (140/141) of patients. Mean number of PEDs implanted per patient was 1.1±0.26; a single PED was used in 92.9% (131/141) of patients. At 1 year, 97.9% (138/141) of patients underwent follow-up angiography with 76.8% (106/138) of patients having met the study’s primary effectiveness endpoint. The combined major morbidity and mortality rate was 2.1% (3/140).ConclusionsTreatment of wide necked small/medium aneurysms with the PED results in high rates of complete occlusion without significant parent vessel stenosis and low rates of permanent neurologic complications.Trial registrationNCT02186561.

The endonasal endoscopic transclival approach represents a less invasive and more direct approach than a transcranial approach to treat certain moderate-sized midline skull base chordomas. Longer follow-up is necessary to determine comparability to transcranial approaches for long-term control. Large tumors with significant extension lateral to the carotid artery may not be suitable for this approach.