STN-DBS electrode placement accuracy and motor improvement in Parkinson's disease: systematic review and individual patient meta-analysis.

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is an effective neurosurgical treatment for Parkinson's disease. Surgical accuracy is a critical determinant to achieve an adequate DBS effect on motor performance. A two-millimetre surgical accuracy is commonly accepted, but scientific evidence is lacking. A systematic review and meta-analysis of study-level and individual patient data (IPD) was performed by a comprehensive search in MEDLINE, EMBASE and Cochrane Library. Primary outcome measures were (1) radial error between the implanted electrode and target; (2) DBS motor improvement on the Unified Parkinson's Disease Rating Scale part III (motor examination). On a study level, meta-regression analysis was performed. Also, publication bias was assessed. For IPD meta-analysis, a linear mixed effects model was used. Forty studies (1391 patients) were included, reporting radial errors of 0.45-1.86 mm. Errors within this range did not significantly influence the DBS effect on motor improvement. Additional IPD analysis (206 patients) revealed that a mean radial error of 1.13±0.75 mm did not significantly change the extent of DBS motor improvement. Our meta-analysis showed a huge publication bias on accuracy data in DBS. Therefore, the current literature does not provide an unequivocal upper threshold for acceptable accuracy of STN-DBS surgery. Based on the current literature, DBS-electrodes placed within a 2 mm range of the intended target do not have to be repositioned to enhance motor improvement after STN-DBS for Parkinson's disease. However, an indisputable upper cut-off value for surgical accuracy remains to be established. PROSPERO registration number is CRD42018089539.

The Intraoperative Microlesion Effect Positively Correlates With the Short-Term Clinical Effect of Deep Brain Stimulation in Parkinson's Disease.

OBJECTIVE: During the surgical procedure of deep brain stimulation (DBS), insertion of an electrode in the subthalamic nucleus (STN) frequently causes a temporary improvement of motor symptoms, known as the microlesion effect (MLE). The objective of this study was to determine the correlation between the intraoperative MLE and the clinical effect of DBS. MATERIALS AND METHODS: Thirty Parkinson's disease (PD) patients with Movement Disorder Society (MDS) Unified Parkinson's Disease Rating Scale (UPDRS) part III (MDS-UPDRS III) scores during bilateral STN-DBS implantation were included in this retrospective study. MDS-UPDRS III subscores (resting tremor, rigidity, and bradykinesia) of the contralateral upper extremity were used. During surgery, these subscores were assessed directly before and after insertion of the electrode. Also, these subscores were determined in the outpatient clinic after 11 weeks on average (on-stimulation). All assessments were performed in an off-medication state (at least 12 hours of medication washout). RESULTS: Postinsertion MDS-UPDRS motor scores decreased significantly compared to preinsertion scores (p < 0.001 for both hemispheres). The MLE showed a positive correlation with the clinical effect of DBS in both hemispheres (rho = 0.68 for the primarily treated hemisphere, p < 0.001, and rho = 0.59 for the secondarily treated hemisphere, p < 0.01). CONCLUSION: The MLE has a clinically relevant correlation with the effect of DBS in PD patients. These results suggest that the MLE can be relied upon as evidence of a clinically effective DBS electrode placement.

A Systematic Review of Definitions for Dysphagia and Dysphonia in Patients Treated Surgically for Degenerative Cervical Myelopathy.

STUDY DESIGN: Systematic review. Surgical decompression for degenerative cervical myelopathy (DCM) is associated with perioperative complications, including difficulty or discomfort with swallowing (dysphagia) as well as changes in sound production (dysphonia). This systematic review aims to (1) outline how dysphagia and dysphonia are defined in the literature and (2) assess the quality of definitions using a novel 4-point rating system. METHODS: An electronic database search was conducted for studies that reported on dysphagia, dysphonia or other related complications of DCM surgery. Data extracted included study design, surgical details, as well as definitions and rates of surgical complications. A 4-point rating scale was developed to assess the quality of definitions for each complication. RESULTS: Our search yielded 2,673 unique citations, 11 of which met eligibility criteria and were summarized in this review. Defined complications included odynophagia (n = 1), dysphagia (n = 11), dysphonia (n = 2), perioperative swelling complications (n = 2), and soft tissue swelling (n = 3). Rates of dysphagia varied substantially (0.0%-50.0%) depending on whether this complication was patient-reported (4.4%); patient-reported using a modified Swallowing Quality of Life questionnaire (43.1%) or the Bazaz criteria (8.8%-50.0%); or diagnosed using an extensive protocol consisting of clinical assessment, a bedside swallowing test, evaluation by a speech and language pathologist and a modified barium swallowing test/fiberoptic endoscopy (42.9%). The reported incidences of dysphonia also ranged significantly from 0.6% to 38.0%. CONCLUSION: There is substantial variability in reported rates of dysphagia and dysphonia due to differences in data collection methods, diagnostic strategies, and definitions. Consolidation of nomenclature will improve evaluation of the overall safety of surgery.

The Role of Magnetic Resonance Imaging to Inform Clinical Decision-Making in Acute Spinal Cord Injury: A Systematic Review and Meta-Analysis.

The clinical indications and added value of obtaining MRI in the acute phase of spinal cord injury (SCI) remain controversial. This review aims to critically evaluate evidence regarding the role of MRI to influence decision-making and outcomes in acute SCI. A systematic review and meta-analysis were performed according to PRISMA methodology to identify studies that address six key questions (KQs) regarding diagnostic accuracy, frequency of abnormal findings, frequency of altered decision-making, optimal timing, and differences in outcomes related to obtaining an MRI in acute SCI. A total of 32 studies were identified that addressed one or more KQs. MRI showed no adverse events in 156 patients (five studies) and frequently identified cord compression (70%, 12 studies), disc herniation (43%, 16 studies), ligamentous injury (39%, 13 studies), and epidural hematoma (10%, two studies), with good diagnostic accuracy (seven comparative studies) except for fracture detection. MRI findings often altered management, including timing of surgery (78%, three studies), decision to operate (36%, 15 studies), and surgical approach (29%, nine studies). MRI may also be useful to determine the need for instrumentation (100%, one study), which levels to decompress (100%, one study), and if reoperation is needed (34%, two studies). The available literature consistently concluded that MRI was useful prior to surgical treatment (13 studies) and after surgery to assess decompression (two studies), but utility before/after closed reduction of cervical dislocations was unclear (three studies). One study showed improved outcomes with an MRI-based protocol but had a high risk of bias. Heterogeneity was high for most findings (I2 > 0.75). MRI is safe and frequently identifies findings alter clinical management in acute SCI, although direct evidence of its impact on outcomes is lacking. MRI should be performed before and after surgery, when feasible, to facilitate improved clinical decision-making. However, further research is needed to determine its optimal timing, effect on outcomes, cost-effectiveness, and utility before and after closed reduction.

A Systematic Review of Definitions for Neurological Complications and Disease Progression in Patients Treated Surgically for Degenerative Cervical Myelopathy.

STUDY DESIGN: Systematic review. OBJECTIVE: This review aims to (1) outline how neurological complications and disease progression are defined in the literature and (2) evaluate the quality of definitions using a novel four-point rating system. SUMMARY OF BACKGROUND DATA: Degenerative cervical myelopathy (DCM) is a progressive, degenerative spine disease that is often treated surgically. Although uncommon, surgical decompression can be associated with neurological complications, such as C5 nerve root palsy, perioperative worsening of myelopathy, and longer-term deterioration. Unfortunately, important questions surrounding these complications cannot be fully addressed due to the heterogeneity in definitions used across studies. Given this variability, there is a pressing need to develop guidelines for the reporting of surgical complications in order to accurately evaluate the safety of surgical procedures. METHODS: An electronic database search was conducted in MEDLINE, MEDLINE in Process, EMBASE and Cochrane Central Register of Controlled Trials for studies that reported on complications related to DCM surgery and included at least 10 surgically treated patients. Data extracted included study design, surgical details, as well as definitions and rates of surgical complications. A four-point rating scale was developed to assess definition quality for each complication. RESULTS: Our search yielded 2673 unique citations, 42 of which met eligibility criteria and were summarized in this review. Defined complications included neurological deterioration, late onset deterioration, perioperative worsening of myelopathy, C5 palsy, nerve root or upper limb palsy or radiculopathy, surgery failure, inadequate decompression and progression of ossified lesions. Reported rates of these complications varied substantially, especially those for neurological deterioration (0.2%-33.3%) and progression of ossified lesions (0.0%-86.7%). CONCLUSION: Reported incidences of various complications vary widely in DCM surgery, especially for neurological deterioration and progression of ossified lesions. This summary serves as a first step for standardizing definitions and developing guidelines for accurately reporting surgical complications. LEVEL OF EVIDENCE: 2.