Anterior communicating artery division in the endoscopic endonasal translamina terminalis approach to the third ventricle: an anatomical feasibility study.

BACKGROUND: Endonasal endoscopic approaches (EEA) to the third ventricle are well described but generally use an infrachiasmatic route since the suprachiasmatic translamina terminalis corridor is blocked by the anterior communicating artery (AComA). The bifrontal basal interhemispheric translamina terminalis approach has been facilitated with transection of the AComA. The aim of the study is to describe the anatomical feasibility and limitations of the EEA translamina terminalis approach to the third ventricle augmented with AComA surgical ligation. METHODS: Endoscopic dissections were performed on five cadaveric heads injected with colored latex using rod lens endoscopes attached to a high-definition camera and a digital video recorder system. A stepwise anatomical dissection of the endoscopic endonasal transtuberculum, transplanum, translamina terminalis approach to the third ventricle was performed. Measurements were performed before and after AComA elevation and transection using a millimeter flexible caliper. RESULTS: Multiple comparison statistical analysis revealed a statistically significant difference in vertical exposure between the control condition and after AComA elevation, between the control condition and after AComA division and between the AComA elevation and division (p < 0.05). The mean difference in exposed surgical area was statistically significant between the control and after AComA division and between elevation and AComA division (p < 0.01), whereas it was not statistically significant between the control condition and AComA elevation (NS). CONCLUSION: The anatomical feasibility of clipping and dividing the AComA through an EEA has been demonstrated in all the cadaveric specimens. The approach facilitates exposure of the suprachiasmatic optic recess within the third ventricle that may be a blind spot during an infrachiasmatic approach.

Vagal nerve stimulation: relationship between outcome and electroclinical seizure pattern.

In recent years, vagal nerve stimulation (VNS) has been proposed as a possible way to improve the control of refractory (partial and generalized) seizures. To date, however, there is no complete understanding of the underlying mechanism for this action nor are there any available guidelines or criteria for the selection of those candidates that might be most suitable for this kind of neuromodulating surgery. This report presents evidence that should be helpful in defining the clinical criteria for using VNS for the treatment of refractory seizures. We report on 17 patients with severe partial refractory epilepsy and polymorphous seizures, who have been operated on previously or who were excluded from epilepsy surgery and for whom, at least, one seizure type has been electrographically recorded. Sixteen of these patients also had falling seizures. Our objective was to identify responders and to correlate the outcome of their seizures with the EEGraphic onset of their seizure. Follow-up ranged from 4 to 9 years. The results of this study indicate a significant reduction of seizures in only four patients and better outcome in patients where the onset of seizure activity occurred in the temporal area. Patients with frontal or frontocentral seizures resulted in the poorest outcomes. In four patients with Lennox-Gastaut syndrome VNS produced no significant reduction of seizures, while falling seizures decreased significantly in three patients with retropulsive falls. These results of this small series of patients suggest that VNS might be more suitable in patients with temporal rather than frontal or central seizure onset. Further studies are required to support this hypothesis.

A simple method to assess accuracy of deep brain stimulation electrode placement: pre-operative stereotactic CT + postoperative MR image fusion.

OBJECTIVE: To describe a method for the measurement of the accuracy of deep brain stimulation (DBS) electrode placement with the use of image fusion technologies. PATIENTS AND METHODS: Ten consecutive patients suffering from movement disorders underwent DBS electrode placement. Postoperative MR images were fused with the pre-operative stereotactic CT. The placement error in the anteroposterior, lateral and vertical planes was calculated. RESULTS: The anteroposterior mean error +/- SD was 0.61 +/- 0.22 mm (range 0.2-0.9 mm). The lateral mean error +/- SD was 0.65 +/- 0.27 mm (range 0.2-2.2 mm). The vertical mean error +/- SD was 0.82 +/- 0.31 mm (range 0.3-1.6 mm). CONCLUSIONS: This technique provides a simple and precise method for the evaluation of the accuracy of DBS electrode placement.

Stimulation of the posterior hypothalamus for treatment of chronic intractable cluster headaches: first reported series.

OBJECTIVE: To describe the results of deep brain stimulation of the ipsilateral posterior hypothalamus for the treatment of drug-resistant chronic cluster headaches (CHs). A technique for electrode placement is reported. METHODS: Because recent functional studies suggested hypothalamic dysfunction as the cause of CH bouts, we explored the therapeutic effectiveness of posterior hypothalamic stimulation for the treatment of CHs. Five patients with intractable chronic CHs were treated with long-term, high-frequency, electrical stimulation of the posterior hypothalamus. Electrodes were stereotactically implanted in the following position: 3 mm behind the midcommissural point, 5 mm below the midcommissural point, and 2 mm lateral to the midline. RESULTS: Since this treatment, all five patients continue to be pain-free after 2 to 22 months of follow-up monitoring. Two of the five patients have remained pain-free without any medication, whereas three of the five required low doses of methysergide (two patients) or verapamil (one patient). No adverse side effects of chronic, high-frequency, hypothalamic stimulation have been observed, and we have not encountered any acute complications resulting from the implant procedure. There have been no tolerance phenomena. CONCLUSION: These preliminary results indicate a role for posterior hypothalamic stimulation, which was demonstrated to be safe and effective, in the treatment of drug-resistant chronic CHs. These data point to a central pathogenesis for chronic CHs.

Chronic motor cortex stimulation for movement disorders: a promising perspective.

Five patients affected by thalamic hand and international myoclonus have been evaluated and selected for chronic motor cortex stimulation. A quadripolar electrode strip was placed epidurally under local anesthesia through an MR-image-guided single precentral burr hole placed following the morphologic recognition of the central sulcus. Intra-operative stimulation was used to induce muscle contraction at the affected site to confirm the correct placement of the electrode. A one-week trial period preceded the implant of an internal pace-maker under general anesthesia. A remarkable decrease in pain was reported by four patients together with the reduction of dystonia and rigidity in thalamic hand and marked decrease of intentional myoclonus. No complications or undesired side effects of electrode implant and stimulation were observed.