Precision targeting in the globus pallidus interna: insights from the multicenter, prospective, blinded VA/NINDS CSP 468 study.

OBJECTIVE: Deep brain stimulation (DBS) targeting the globus pallidus interna (GPi) has been shown to significantly improve motor symptoms for the treatment of medication-refractory Parkinson's disease. Yet, heterogeneity in clinical outcomes persists, possibly due to suboptimal target identification within the GPi. By leveraging robust sampling of the GPi and 6-month postsurgical outcomes, this study aims to determine optimal symptom-specific GPi DBS targets. METHODS: In this study, the authors analyzed the anatomical lead location and 6-month postsurgical, double-blinded outcome measures of 86 patients who underwent bilateral GPi DBS. These patients were selected from the multicenter Veterans Affairs (VA)/National Institutes of Neurological Disorders and Stroke (NINDS) Cooperative Studies Program (CSP) 468 study to identify the optimal target zones ("sweet spots") for the control of overall motor (United Parkinson's Disease Rating Scale [UPDRS]-III), axial, tremor, rigidity, and bradykinesia symptoms. Lead coordinates were normalized to Montreal Neurological Institute space and the optimal target zones were identified and validated using a leave-one-patient-out approach. RESULTS: The authors' findings revealed statistically significant optimal target zones for UPDRS-III (R = 0.37, p < 0.001), axial (R = 0.22, p = 0.042), rigidity (R = 0.20, p = 0.021), and bradykinesia (R = 0.23, p = 0.004) symptoms. These zones were localized within the primary motor and premotor subdivisions of the GPi. Interestingly, these zones extended beyond the GPi lateral border into the GPi-globus pallidus externa (GPe) lamina and into the GPe, but they did not reach the GPi ventral border, challenging traditional surgical approaches based on pallidotomies. CONCLUSIONS: Drawing upon a robust dataset, this research effectively delineates specific optimal target zones for not only overall motor improvement but also symptom subscores. These insights hold the potential to enhance the precision of targeting in subsequent bilateral GPi DBS surgical procedures.

Management of rare atlantoaxial synovial cyst case with extension to the cerebellopontine angle: illustrative case.

BACKGROUND: Synovial cysts are a common finding in degenerative spine disease, most frequently involving the facet joints of the lumbar spine. Synovial cysts are less common in the cervical spine and rarely involve the atlantoaxial junction. OBSERVATIONS: In this case report, the authors detail a unique presentation of a left atlantoaxial synovial cyst with large intracranial extension into the cerebellopontine angle causing progressive cranial nerve palsies resulting in tinnitus, vertigo, diminished hearing, gait imbalance, left trigeminal hypesthesia, left facial weakness, and dysarthria. The patient underwent a retromastoid craniectomy for resection of the synovial cyst, resulting in improvement and resolution of symptoms. Follow-up occurred at 6 weeks, 3 months, and 5 months postoperatively without recurrence on imaging. LESSONS: The authors describe acute and long-term management of a unique presentation of an atlantoaxial synovial cyst including retromastoid craniectomy, intervals for follow-up for recurrence, and possible treatment options in cases of recurrence. A systematic literature review was also performed to explore all reported cases of craniocervical junction synovial cysts and subsequent surgical management.

The Poised Cannula Technique Reduces the Stereotactic Error of the Fiducial-Less Frameless DBS Procedure.

BACKGROUND: In this study, we describe a technique of optimizing the accuracy of frameless deep brain stimulation (DBS) lead placement through the use of a cannula poised at the entry to predict the location of the fully inserted device. This allows real-time correction of error prior to violation of the deep gray matter. METHODS: We prospectively gathered data on radial error during the operative placements of 40 leads in 28 patients using frameless fiducial-less DBS surgery. Once the Nexframe had been aligned to target, a cannula was inserted through the center channel of the BenGun until it traversed the pial surface and a low-dose O-arm spin was obtained. Using 2 points along the length of the imaged cannula, a trajectory line was projected to target depth. If lead location could be improved, the cannula was inserted through an alternate track in the BenGun down to target depth. After intraoperative microelectrode recording and clinical assessment, another O-arm spin was obtained to compare the location of the inserted lead with the location predicted by the poised cannula. RESULTS: The poised cannula projection and the actual implant had a mean radial discrepancy of 0.75 ± 0.64 mm. The poised cannula projection identified potentially clinically significant errors (avg 2.07 ± 0.73 mm) in 33% of cases, which were reduced to a radial error of 1.33 ± 0.66 mm (p = 0.02) after correction using an alternative BenGun track. The final target to implant error for all 40 leads was 1.20 ± 0.52 mm with only 2.5% of errors being >2.5 mm. CONCLUSION: The poised cannula technique results in a reduction of large errors (>2.5 mm), resulting in a decline in these errors to 2.5% of implants as compared to 17% in our previous publication using the fiducial-less method and 4% using fiducial-based methods of DBS lead placement.

Mycobacterium fortuitum Meningitis: Approach to Lumboperitoneal Shunt Infection.

Mycobacterium fortuitum is a rare, opportunistic pathogen most frequently contracted through contact with a contaminated source. An immunocompetent 26-year-old female patient presented to our institution with an infected lumboperitoneal (LP) shunt presenting as continued nonhealing wounds. After multiple debridements, shunt revisions, and wound closure failures, infectious disease specialists were consulted. The wound cultures returned positive for M. fortuitum and the shunt was removed. Cerebrospinal fluid studies revealed significant pleocytosis with normal opening pressure, and the patient was diagnosed as having secondary meningitis. After shunt removal, the patient was treated with intravenous and oral antibiotics, resulting in infection resolution. Five months later, a new LP shunt was placed without infection recurrence. Although M. fortuitum was previously reported in neurosurgical patients with ventriculoperitoneal shunts, which are summarized here, to date this is the first case in the literature of M. fortuitum meningitis from an LP shunt. This case demonstrates the importance of clinicians considering uncommon and slow-growing pathogens, as well as consulting infectious disease specialists for patients with persistent, unexplained infections.

Spinal subdural hematoma and ankylosing spondylitis: case report and review of literature.

INTRODUCTION: Spinal subdural hematomas are rare, disabling hemorrhages. Ankylosing spondylitis (AS) is a relatively common inflammatory condition of the spine that can progress to a fragile, unstable fusion vulnerable to fracture. While spinal epidural hematomas have been described, subdural hematomas to date have not been reported in AS. In this report, we describe the unique case of a patient on warfarin with AS who developed a spinal subdural hematoma and fracture in the absence of trauma. We then discuss the pathogenesis, presentation, prognosis, and management strategies for this unique diagnosis. CASE PRESENTATION: A 60-year-old man with recent AS diagnosis and atrial fibrillation on warfarin presented with 96 h of low back pain and 24 h of leg weakness and urinary retention. CT imaging revealed a bamboo spine and fracture of the posterior elements at L4, while MR revealed a hematoma with thecal sac compression. The warfarin was reversed and the patient taken to the operating room; on laminectomy, however, no hematoma was encountered. The patient then underwent intraoperative ultrasound, durotomy, and evacuation of a thick subdural hematoma, followed by posterior fusion. DISCUSSION: This case represents the first report of an AS patient who developed a subdural hematoma requiring evacuation. Although rare, the clinician should maintain a broad differential and be familiar with this unique pathology, particularly in high-risk patients, such as those with suspected fractures or on warfarin. In patients with back pain and myelopathic symptoms, rapid diagnosis followed by prompt evacuation allows for the best opportunity for neurologic recovery.