Connectivity-based thalamus parcellation and surgical targeting of somatosensory subnuclei.

OBJECTIVE: The anatomy of the posterolateral thalamus varies substantially between individuals, presenting a challenge for surgical targeting. Patient-specific, connectivity-based parcellation of the thalamus may effectively approximate the ventrocaudal nucleus (Vc). This remains to be robustly validated or assessed as a method to guide surgical targeting. The authors assessed the validity of connectivity-based parcellation for targeting the Vc and its potential for improving clinical outcomes of pain surgery. METHODS: A cohort of 19 patients with regional, chronic neuropathic pain underwent preoperative structural and diffusion MRI, then progressed to deep brain stimulation targeting the Vc based on traditional atlas coordinates. Surgical thalami were retrospectively segmented and then parcellated based on tractography estimates of thalamocortical connectivity. The location of each patient's electrode array was analyzed with respect to their primary somatosensory cortex (S1) parcel and compared across patients with reference to the thalamic homunculus. RESULTS: Ten patients achieved long-term pain relief. Sixty-one percent of an average array (interquartile range 42%-74%) was located in the S1 parcel. In patients who achieved long-term benefit from surgery, array location in the individually generated S1 parcels was medial for face pain, centromedial for arm pain, and centrolateral for leg pain. Patients who did not benefit from surgery did not follow this pattern. Standard stereotactic coordinates of electrode locations diverged from this pattern. CONCLUSIONS: Connectivity-based parcellation of the thalamus appears to be a reliable method for segmenting the Vc. Identifying the Vc in this way, and targeting mediolaterally as appropriate for the region of pain, merits exploration in an effort to increase the yield of successful surgical procedures.

Human Dorsal Root Ganglion Stimulation Reduces Sympathetic Outflow and Long-Term Blood Pressure.

This study hypothesized that dorsal root ganglion (DRG) stimulation would reduce sympathetic nerve activity and would alter hemodynamic variables. This study directly recorded muscle sympathetic nerve activity during ON and OFF stimulation of the DRG while measuring hemodynamic parameters. DRG stimulation significantly reduced the firing frequency of sympathetic nerves, as well as significantly reducing blood pressure, with greater reductions evident when stimulation was left-sided. Left-sided DRG stimulation lowers sympathetic nerve activity, leading to long-term phenotypic changes. This raises the potential of DRG stimulation being used to treat de novo autonomic disorders such as hypertension or heart failure.

30-day outcomes in hip fracture patients during the COVID-19 pandemic compared to the preceding year.

AIMS: To establish if COVID-19 has worsened outcomes in patients with AO 31 A or B type hip fractures. METHODS: Retrospective analysis of prospectively collected data was performed for a five-week period from 20 March 2020 and the same time period in 2019. The primary outcome was mortality at 30 days. Secondary outcomes were COVID-19 infection, perioperative pulmonary complications, time to theatre, type of anaesthesia, operation, grade of surgeon, fracture type, postoperative intensive care admission, venous thromboembolism, dislocation, infection rates, and length of stay. RESULTS: In all, 76 patients with hip fractures were identified in each group. All patients had 30-day follow-up. There was no difference in age, sex, American Society of Anesthesiologists (ASA) classification or residence at time of injury. However, three in each group were not fit for surgery. No significant difference was found in 30-day mortality; ten patients (13%) in 2019 and 11 patients (14%) in 2020 (p = 0.341). In the 2020 cohort, ten patients tested positive for COVID-19, two (20%) of whom died. There was no significant increase in postoperative pulmonary complications. Median time to theatre was 20 hours (interquartile range (IQR) 16 to 25) in 2019 versus 23 hours (IQR 18 to 30) in 2020 (p = 0.130). Regional anaesthesia increased from 24 (33%) cases in 2019 to 46 (63%) cases in 2020, but ten (14%) required conversion to general anaesthesia. In both groups, 53 (70%) operations were done by trainees. Hemiarthroplasty for 31 B type fractures was the most common operation. No significant difference was found for intensive care admission or 30-day venous thromboembolism, dislocation or infection, or length of stay. CONCLUSION: Little information exists on mortality and complications after hip fracture during the COVID-19 pandemic. At the time of writing, no other study of outcomes in the UK has been published.Cite this article: Bone Joint Open 2020;1-7:415-419.

Dorsal Root Ganglion Stimulation for the Treatment of Chronic Neuropathic Knee Pain.

BACKGROUND: To elucidate the efficacy of dorsal root ganglion stimulation in the treatment of chronic neuropathic pain confined to the knee. METHODS: Retrospective analysis of prospectively collected data of 14 consecutive patients undergoing dorsal root ganglion stimulation for chronic knee pain, in a single center. The primary outcome measure was pain reduction assessed by numeric pain rating scale score preoperatively and postoperatively. Secondary outcomes included quantification of percentage of pain area covered by stimulation, and reduction in usage of opioid medications. Responders were defined as patients that experienced a greater than or equal to 50% improvement in their preoperative pain score. RESULTS: Fourteen patients were implanted with dorsal root ganglion stimulator electrodes; 8 had a single L3 lead implanted, 1 patient had a single L4 lead implanted, and 3 patients had 2 leads implanted (L3 and L4). Two patients had their leads explanted: 1 for non-efficacy, and 1 for repeated electrode displacement. The most common indication for surgery was type 2 complex regional pain syndrome, secondary to either trauma or postoperative chronic pain (either knee replacement or arthroscopy). Median preoperative numeric rating scale score was 8.5, median postoperative numeric rating scale score was 2 (P = 0.002, Wilcoxon signed rank test). The median improvement in pain score was 80%. All 12 patients undergoing chronic stimulation were responders. Median coverage of pain area was 85%. All but 1 patient who was on opioid medication prior to surgery had reduced the dosage of regular opioid. CONCLUSIONS: In selected patients, dorsal root ganglion stimulation is an extremely efficacious means of treating otherwise refractory chronic knee pain.

The pedunculopontine region and breathing in Parkinson's disease.

OBJECTIVE: Respiratory abnormalities such as upper airway obstruction are common in Parkinson's disease (PD) and are an important cause of mortality and morbidity. We tested the effect of pedunculopontine region (PPNr) stimulation on respiratory maneuvers in human participants with PD, and separately recorded PPNr neural activity reflected in the local field potential (LFP) during these maneuvers. METHODS: Nine patients with deep brain stimulation electrodes in PPNr, and seven in globus pallidus interna (GPi) were studied during trials of maximal inspiration followed by forced expiration with stimulation OFF and ON. Local field potentials (LFPs) were recorded in the unstimulated condition. RESULTS: PEFR increased from 6.41 ± 0.63 L/sec in the OFF stimulation state to 7.5 L ± 0.65 L/sec in the ON stimulation state (z = -2.666, df = 8, P = 0.024). Percentage improvement in PEFR was strongly correlated with proximity of the stimulated electrode contact to the mesencephalic locomotor region in the rostral PPN (r = 0.814, n = 9, P = 0.008). Mean PPNr LFP power increased within the alpha band (7-11 Hz) during forced respiratory maneuvers (1.63 ± 0.16 µV2/Hz) compared to resting breathing (0.77 ± 0.16 µV2/Hz; z = -2.197, df = 6, P = 0.028). No changes in alpha activity or spirometric indices were seen with GPi recording or stimulation. Percentage improvement in PEFR was strongly positively correlated with increase in alpha power (r = 0.653, n = 14 (7 PPNr patients recorded bilaterally), P = 0.0096). INTERPRETATION: PPNr stimulation in PD improves indices of upper airway function. Increased alpha-band activity is seen within the PPNr during forced respiratory maneuvers. Our findings suggest a link between the PPNr and respiratory performance in PD.

More than meets the MRI: case report of a carcinoid tumour metastasis mimicking a meningioma.

Cerebral metastases from carcinoid tumours are rarely reported and confer a much poorer prognosis than carcinoid metastases elsewhere in the body. We describe a case of carcinoid brain metastasis closely resembling a meningioma on magnetic resonance imaging (MRI), and review current treatment options.

The Prevalence of Cerebrovascular Abnormalities Detected in Various Diagnostic Subgroups of Spontaneous Subarachnoid Hemorrhage in the Modern Era.

OBJECTIVE: To determine prevalence of cerebrovascular abnormalities in diagnostic subgroups of spontaneous subarachnoid hemorrhage (SAH) in a regional neurosurgical center in the modern era. METHODS: Data of 609 consecutive patients with spontaneous SAH in a 3-year period (August 2010 to August 2013) were prospectively collected. Patients were divided into 3 diagnostic subgroups: computed tomography (CT) positive for SAH; CT negative but positive cerebrospinal fluid examination by spectrophotometry for SAH; CT negative for SAH and inconclusive cerebrospinal fluid examination. All patients fit for intervention underwent CT angiography with or without digital subtraction angiography to identify vascular abnormalities for subsequent treatment. RESULTS: Of 609 patients, 554 were fit for further investigation and consideration of further intervention; 514 patients had confirmed SAH. Mean patient age was 54.0 years; 61.5% of patients were women. Of patients, 390 (75.9%) showed vascular abnormalities on angiography. There were 438 patients (85.2%) with confirmed SAH diagnosed on CT scan (group 1). Vascular abnormalities were detected in 81.1% of patients; 18.9% of patients with positive CT scan had no identifiable cause of SAH. Of patients with confirmed SAH, 76 (14.8%) had negative CT scan but positive lumbar puncture (group 2); 46.1% of patients in this group had vascular abnormalities. Three patients with inconclusive cerebrospinal fluid examination had lesions requiring treatment. Median length of hospital stay in group 1 patients was longer than median length of hospital stay in group 2 patients. CONCLUSIONS: Frequency of vascular abnormalities in spontaneous SAH is lower than the traditionally quoted figure, which has diagnostic and prognostic implications for patient management.

Routine radiographs one day after anterior cervical discectomy and fusion are neither necessary nor cost-effective.

OBJECTIVES: Anterior cervical discectomy and fusion (ACDF) is a common operative treatment of compressive pathology of the cervical spinal cord, when caused by one or more degenerated intervertebral discs or related osteophytes. In addition to intra-operative radiographs to confirm spinal level before discectomy and implant position after insertion, traditional practice is to obtain post-operative antero-posterior and lateral plain radiographs (XR) before hospital discharge, despite a paucity of evidence supporting their benefit to patient care. Minimising unnecessary radiation to radiosensitive neck structures is desirable, and furthermore, with increasing financial pressure on healthcare resources, routine investigations should be clinically justified and evidence-based. We aim to compare the utility of routine post-operative cervical spine X-rays following ACDF. METHODS: We compare two groups of consecutive patients undergoing ACDF in a single UK neurosurgical centre. The first group (n = 109) received routine post-operative XR imaging, and the second group (n = 113) received radiographs only when clinically indicated. RESULTS: There were no differences in post-operative complication rates (4.6% vs. 5.3%), or requirement for further imaging or of further operative intervention (1.8% vs. 0.9%). The group that did not have routine post-operative radiographs had a significantly shorter stay in hospital (median two days vs. three days). There were no patients in either group where post-operative XR changed clinical management and mandated revision surgery or further imaging. All cases requiring surgery or further imaging were identified by clinical deterioration. CONCLUSIONS: We suggest that the practice of obtaining routine radiographs of the cervical spine following ACDF should be abandoned, unless there is a clear clinical indication.

Optimising treatment strategies in spinal ependymoma based on 20years of experience at a single centre.

Spinal ependymomas are rare tumours, with total resection favoured where possible. Several case series assessing the outcome following neurosurgical treatment for spinal ependymoma advocate the usage of adjuvant radiotherapy in cases of subtotal resection, or in unencapsulated tumours. We assessed the outcome of 61 consecutive cases of spinal ependymoma in a single centre over a 20year period using a variety of outcome measures. Sex distribution was equal, with a mean age at surgery of 43.6years (range 5-76years). Overall, most tumours occurred in the lumbosacral region (70.5%), with fewer in the thoracic (27.9%) and cervical regions (18.0%). Myxopapillary features were seen in 41.0% of tumours, and were more common when occurring in the lumbar region (51.2%). Gross total resection was achieved in 52.5%, subtotal resection in 37.7% and biopsy alone in 9.8% of patients and 31.1% received adjuvant radiotherapy. Two-thirds of patients achieved an excellent post-operative neurological outcome (Frankel grade E). Tumour recurrence was rare. Gross total resection and good preoperative neurological condition were most strongly predictive of good outcome. Post-operative radiotherapy did not seem to confer survival benefit in this case series, even in cases of incomplete resection, leading us to question its utility for all cases of spinal cord ependymoma.

Defending a traditional practice in the modern era: The use of lumbar puncture in the investigation of subarachnoid haemorrhage.

INTRODUCTION: Acute severe headache is a common medical presentation, and a common area of diagnostic uncertainty. Subarachnoid haemorrhage (SAH) is the cause in a minority of patients and has a high rate of morbidity and mortality. Therefore, its conclusive diagnosis with computed tomography (CT) or lumbar puncture (LP) is paramount. With advancement in imaging technology, emerging evidence now suggests that LP is no longer required for a subset of patients as CT has 100% sensitivity in detecting SAH, when performed under specific conditions. OBJECTIVES: To assess the proportion of patients with conclusive CSF xanthochromia results following a negative CT scan in suspected SAH to determine the diagnostic efficacy of LP. METHODS: CSF bilirubin and oxyhaemoglobin spectrophotometric absorbance data from all centres in a regional health board were identified for consecutive patients over a 6-month period. Results were stratified as conclusive (positive or negative), or inconclusive according to national guidelines. RESULTS: 239 of 255 (93.7%) results were conclusive: 89.0% were negative (227 of 255). 4.7% of results were positive (12 of 255), revealing 4 cerebral aneurysms requiring treatment. 16 out of 255 (6.3%) samples were inconclusive, yielding 1 aneurysm requiring treatment. In the same period, there were 27 CT-positive cases of SAH. CONCLUSIONS: LP has a high diagnostic yield, eliminating the need for neurosurgical opinion or investigation in almost 90% of cases. The test is both cost and time efficient and subjects only a small number of patients to the radiation and contrast risks of angiography.

The Diagnosis and Management of Brain Arteriovenous Malformations in a Single Regional Center.

BACKGROUND: Cerebral arteriovenous malformations are vascular abnormalities in which arteriovenous shunting occurs through an abnormal vascular network (nidus) in the parenchyma. These lesions typically present by the third decade of life with cerebral bleeding, seizures, headache, or neurologic deficits; however, they are sometimes found incidentally. METHODS: A retrospective analysis of intracranial AVMs referred to a single regional center, over a 7-year period, was performed to review the clinical presentation, pathologic features and management outcomes from January 2005 to December 2012. RESULTS: We identified 142 patients (56% female, age range 4-69 years). Emergency referrals accounted for 87% of the cohort with the most frequent presentation being headache and/or hemorrhage. More than half (52%) of the cases were observed to have a neurologic deficit on examination. The modal Spetzler-Martin Grade was 3 with 76% of lesions located in areas of eloquent brain and 57% of cases in the dominant hemisphere. Half of the cases had multiple feeder vessels, and 29% were associated with aneurysms. The nidus was obliterated in 91% of cases actively managed. Two thirds of patients were successfully treated with a single modality, the most common being embolization. Only 8% of cases were managed conservatively. Additionally, 93% of aneurysms identified were treated successfully. The complication rate was 7% with 2% of reported infection. CONCLUSIONS: The burden of AVM management is significantly enhanced by the number of emergency referrals. Interestingly, complication rates are higher in the unruptured cohort. Surgical management is the most effective modality, but it carries the highest complication rate. This accompanied by the challenges of AVM anatomy and associated pathology argue for expert service provision in a single center.