The caudal zona incerta target within the posterior subthalamic area is an investigational site for deep brain stimulation (DBS) in Parkinson disease (PD) and tremor. The authors report on a patient with tremor-predominant PD who, despite excellent tremor control and an otherwise normal neurological examination, exhibited profound difficulty swimming during stimulation. Over the last 20 years, anecdotal reports have been received of 3 other patients with PD who underwent thalamic or pallidal lesioning or DBS surgery performed at the authors' center and subsequently drowned. It may be that DBS puts patients at risk for drowning by specifically impairing their ability to swim. Until this finding can be further examined in larger cohorts, patients should be warned to swim under close supervision soon after DBS surgery.
OBJECTIVEPosterior subthalamic area (PSA) deep brain stimulation (DBS) targeting the zona incerta (ZI) is an emerging treatment for tremor syndromes, including Parkinson’s disease (PD) and essential tremor (ET). Evidence from animal studies has indicated that the ZI may play a role in saccadic eye movements via pathways between the ZI and superior colliculus (incerto-collicular pathways). PSA DBS permitted testing this hypothesis in humans.METHODSSixteen patients (12 with PD and 4 with ET) underwent DBS using the MRI-directed implantable guide tube technique. Active electrode positions were confirmed at the caudal ZI. Eye movements were tested using direct current electrooculography (EOG) in the medicated state pre- and postoperatively on a horizontal predictive task subtending 30°. Postoperative assessments consisted of stimulation-off, constituting a microlesion (ML) condition, and high-frequency stimulation (HFS; frequency = 130 Hz) up to 3 V.RESULTSWith PSA HFS, the first saccade amplitude was significantly reduced by 10.4% (95% CI 8.68%–12.2%) and 12.6% (95% CI 10.0%–15.9%) in the PD and ET groups, respectively. With HFS, peak velocity was reduced by 14.7% (95% CI 11.7%–17.6%) in the PD group and 27.7% (95% CI 23.7%–31.7%) in the ET group. HFS led to PD patients performing 21% (95% CI 16%–26%) and ET patients 31% (95% CI 19%–38%) more saccadic steps to reach the target.CONCLUSIONSPSA DBS in patients with PD and ET leads to hypometric, slowed saccades with an increase in the number of steps taken to reach the target. These effects contrast with the saccadometric findings observed with subthalamic nucleus DBS. Given the location of the active contacts, incerto-collicular pathways are likely responsible. Whether the acute finding of saccadic impairment persists with chronic PSA stimulation is unknown.
BACKGROUND AND IMPORTANCE Cavum septum pellucidum (CSP) and cavum vergae (CV) cysts are common incidental findings on imaging studies. However, they may rarely present with symptoms related to the obstruction of the foramen of Monro by the cyst leaflets. There is no consensus regarding the management of symptomatic CSP and CV cysts. We present an original transcavum interforniceal endoscopic fenestration technique. The step-by-step surgical procedure and two illustrative cases are presented. CLINICAL PRESENTATION A 31-yr-old male and a 24-yr-old woman presented with symptomatic CSP and CV cysts. For both patients, neuronavigation was used to plan the procedure. An endoscope was introduced into the cyst through a right frontal burr-hole. After an examination of the endoscopic anatomy, a communication between the cyst and the third ventricle was performed using an endoscopic forceps. In both cases, directly after the fenestration, cerebrospinal fluid (CSF) passed through the communication, and the collapse of the cyst was appreciated. Symptoms were relieved in both patients, and neuropsychological assessment improved. Postoperative imaging showed a reduction in the cyst bulge, and patent foramen of Monro. CONCLUSION Endoscopic fenestration of CSP and CV cysts to the third ventricle through an interforniceal navigated approach is a feasible and efficient surgical procedure. Theoretical advantages include a single tract through noneloquent brain, a perpendicular trajectory to the membrane for fenestration, and a large CSF space beyond the fenestration point.
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