Accuracy, precision, and safety of stereotactic, frame-based, intraoperative MRI-guided and MRI-verified deep brain stimulation in 650 consecutive procedures.

OBJECTIVE: Suboptimal lead placement is one of the most common indications for deep brain stimulation (DBS) revision procedures. Confirming lead placement in relation to the visible anatomical target with dedicated stereotactic imaging before terminating the procedure can mitigate this risk. In this study, the authors examined the accuracy, precision, and safety of intraoperative MRI (iMRI) to both guide and verify lead placement during frame-based stereotactic surgery. METHODS: A retrospective analysis of 650 consecutive DBS procedures for targeting accuracy, precision, and perioperative complications was performed. Frame-based lead placement took place in an operating room equipped with an MRI machine using stereotactic images to verify lead placement before removing the stereotactic frame. Immediate lead relocation was performed when necessary. Systematic analysis of the targeting error was calculated. RESULTS: Verification of 1201 DBS leads with stereotactic MRI was performed in 643 procedures and with stereotactic CT in 7. The mean ± SD of the final targeting error was 0.9 ± 0.3 mm (range 0.1-2.3 mm). Anatomically acceptable lead placement was achieved with a single brain pass for 97% (n = 1164) of leads; immediate intraoperative relocation was performed in 37 leads (3%) to obtain satisfactory anatomical placement. General anesthesia was used in 91% (n = 593) of the procedures. Hemorrhage was noted after 4 procedures (0.6%); 3 patients (0.4% of procedures) presented with transient neurological symptoms, and 1 experienced delayed cognitive decline. Two bleeds coincided with immediate relocation (2 of 37 leads, 5.4%), which contrasts with hemorrhage in 2 (0.2%) of 1164 leads implanted on the first pass (p = 0.0058). Three patients had transient seizures in the postoperative period. The seizures coincided with hemorrhage in 2 of these patients and with immediate lead relocation in the other. There were 21 infections (3.2% of procedures, 1.5% in 3 months) leading to hardware removal. Delayed (> 3 months) retargeting of 6 leads (0.5%) in 4 patients (0.6% of procedures) was performed because of suboptimal stimulation benefit. There were no MRI-related complications, no permanent motor deficits, and no deaths. CONCLUSIONS: To the authors' knowledge, this is the largest series reporting the use of iMRI to guide and verify lead location during DBS surgery. It demonstrates a high level of accuracy, precision, and safety. Significantly higher hemorrhage was encountered when multiple brain passes were required for lead implantation, although none led to permanent deficit. Meticulous audit and calibration can improve precision and maximize safety.

Right- Versus Left-sided Exposures of the Recurrent Laryngeal Nerve and Considerations of Cervical Spinal Surgical Corridor: A Fresh-Cadaveric Surgical Anatomy of RLN Pertinent to Spine.

STUDY DESIGN: Cadaveric study on fresh unprocessed, nonpreserved, undyed specimens which have not previously been reported. OBJECTIVE: We aimed to perform surgically relevant exposures of the anterior cervical spine with particular attention to observing the potential vulnerabilities of the RLN on right and left. SUMMARY OF BACKGROUND DATA: Vulnerability of the RLN in the anterior cervical spine approach on the right versus left is the subject of ongoing debate. Although most cadaveric studies focus on course variations, structural relations of RLN, they have been done in preserved (fixed) cadavers without relevance to the needs of spinal exposure. METHODS: Twelve fresh undyed cadavers had extensive layer by layer dissections by 2 surgeons (one with extensive experience as anatomy dissector). Both sides were explored for vulnerability during cervical spinal procedures. Each dissection was carried out in a phased approach and deliberately explored beyond what can be afforded in live surgery to allow the reader to conceptualize a better view of the structures. RESULTS: In all specimens, we consistently demonstrated that the right surgical corridor involved manipulation of the nerve and its branches especially below C5 to achieve optimum midline access: in the right corridor, the RLN is on its oblique course to the tracheoesophageal groove. On the left, RLN is already in the tracheoesophageal groove and out of the surgical field involving minimal direct mobilization of the nerve. CONCLUSION: RLN surgical anatomy photographed here is novel in using fresh unprocessed cadaveric specimens which has previously not been reported.Right surgical corridor, below C5, involves retraction/manipulation of RLN for achieving optimum spinal midline access, highlighting potential surgical vulnerability of right RLN. LEVEL OF EVIDENCE: 3.

Berry's Ligament and the Inferior Thyroid Artery as reliable anatomical landmarks for the Recurrent Laryngeal Nerve (RLN): a fresh-cadaveric study of the cervical spine. The RLN relevant to spine.

BACKGROUND CONTEXT: Although most cadaveric studies of the Recurrent Laryngeal Nerve (RLN) have focused on course variations, they have usually been done on preserved (fixed and embalmed) cadavers, which renders the RLN immobile and of less surgical landmark value. PURPOSE: Our aim was to perform a thorough exposure in fresh cadavers, with the intention of investigating the Inferior Thyroid Artery (ITA) and Berry's ligament as reliable landmarks for the identification of the RLN in anterior cervical spine surgery. STUDY DESIGN/SETTING: Eight fresh cadavers had layer by layer dissections by two surgeons (one with extensive experience as anatomy dissector) from C2 to T2-T3, with particular attention to illustrating the surgical anatomy of the RLN pertinent to spine. METHODS: We exposed, traced, and referenced the position of RLNs along their entire length bilaterally and examined the reliability of using ITA and superficial fascia of Berry's Ligament as landmark. RESULTS: In all specimens, we were able to verify the entire course of RLNs on both the right and left sides in all cadavers dissected in detail from origin to insertion. The RLNs were consistently associated with the ITA and Berry's ligament bilaterally, with the RLNs passing almost perpendicular to these structures. CONCLUSIONS: We found that the most reliable anatomical landmark for the RLN bilaterally was the ITA and Berry's ligament, both of which would be encountered as readily identifiable structures in anterior cervical spinal exposure before the nerve itself. We believe this will help spinal surgeons to refine their surgical technique to identify RLN where necessary, thus preventing iatrogenic injury. Our landmark protocol of FEEL-LOOK-AVOID can serve as an easy aide-mémoire for intraoperative surgical anatomy of the RLN during ACDF regardless of side.

Reoperation rates in the surgical treatment of spinal metastases.

BACKGROUND CONTEXT: The surgical treatment in spinal metastases has been shown to improve function and neurologic outcome. Unplanned hospital readmissions can be costly and cause unnecessary harm. PURPOSE: Our aim was to first analyze the reoperation rate and indications for this revision surgery in spinal metastases from an academic tertiary spinal institute and, second, to make comparisons on outcome (neurology and survival) against patients who underwent single surgery only. STUDY DESIGN/SETTING: This was an ambispective review of all patients treated surgically over an 8-year period considering their neurologic and survival outcome data. Statistical analysis was performed using IBM SPSS 20. Because all scale values did not follow the normal distribution and significant outlier values existed, all descriptive statistics and comparisons were made using median values and the median test. Crosstabs and Pearson correlation were used to calculate differences between percentages and ordinal/nominal values. For two population proportions, the z test was used to calculate differences. The log-rank Mantel-Cox analysis was used to compare survival. PATIENT SAMPLE: During the 8 years' study period, there were 384 patients who underwent urgent surgery for spinal metastasis. Of these, 289 patients were included who had sufficient information available. There were 31 reoperations performed (10.7%; mean age, 60 years; 13 male, 18 female). Exclusion criteria included patients treated solely by radiotherapy, patients who had undergone surgery for spinal metastasis before the study period, and those who had other causes for neurologic dysfunction such as stroke. OUTCOME MEASURES: The outcomes considered in this study were revised Tokuhashi score, preoperative/postoperative Frankel scores, and survival. METHODS: We performed an ambispective review of all patients treated surgically from our comprehensive database during the study period (October 2004 to October 2012). We reviewed all patient records on the database, including patient demographics and reoperation rates. RESULTS: Reoperations were performed in the same admission in the majority of patients (n=20), whereas 11 patients had their second procedure in subsequent hospitalization. The reasons for their revision surgery were as follows: surgical site infection (SSI; 13 of 31 [42%]), failure of instrumentation (9 of 31 [29%]), local recurrence (5 of 31 [16%]), hematoma evacuation (2 of 31 [6%]), and others (2 of 31 [6%]).When comparing the "single surgery" and "revision surgery" groups, we found that the median preoperative and postoperative Frankel scores were similar at Grade 4 (range, 1-5) for both groups (preoperative, p=.92; postoperative, p=.87). However, 20 patients (8%) from the single surgery group and 7 (23%) from the revision group had a worse postoperative score, and this was significantly different (p=.01). No significant difference was found (p=.66) in the revised Tokuhashi score. The median number of survival days was similar (p=.719)-single surgery group: 250 days (range, 5-2,597 days) and revision group: 215 days (range, 9-1,352 days). CONCLUSION: There was a modest reoperation rate (10.7%) in our patients treated surgically for spinal metastases over an 8-year period. Most of these were for SSI (42%), failure of instrumentation (26%), and local recurrence (16%). Patients with metastatic disease could benefit from revision surgery with comparable median survival rates but relatively poorer neurologic outcomes. This study may help to assist with informed decision making for this vulnerable patient group.