Presentations selected from submitted abstracts
Intraspinal tumours : The value of diffusion tensor imaging (DTI) and tractography : A preliminary study
Aims:The aim of this prospective study was to evaluate the value of diffusion tensor imaging in intraspinal cord tumors .Despites the advances made in microsurgical neurosurgery, operations of spinal cord tumors remains challenging. Diffusion weighted imaging is a MR technique that has seen vast application with many efforts undertaken to apply the technique in spinal cord pathologies. Methods:Diffusion tensor imaging was performed in 31 patients with intraspinal lesions. Patients underwent MR imaging on a 3.0T magnet (Verio, Siemens).A standardized MR imaging protocol for the cervical spine was used including T2 and T1-weighted as well as gadolinium enhanced T1 weighted imaging. For diffusion tensor imaging a SE EPI sequence was used in 2 orientations with b-factors of 0 and 900 mm2/sec. 3D Tractography were calculated for all patients. Patients were classified into 3 groups according to the fiber course with respect to the lesion. Furthermore the lesions were rated as resectable or non-resectable. Results:Of the 31 patients (16 male, 15 female; mean age 47,7 ± 17 years, range: 19-74 years), 17 patients showed intramedullary tumors, 12 Patients presented extramedullary intradural tumors and 2 patients had epidural masses. 8 patients had ependymomas, 6 patients had meningiomas, 3 patients had cavernomas, 1 patient showed a ODG another a LGG, 1 patient had a GBM. 1 patient had a chordoma. One patient presented with an hemangioblastoma, 3 patients showed schwannoma and of 1 patient had no histology but a hemangioblastoma was suspected. In 1 patient biopsy was inconclusive-imaging suspected an ependymoma. 2 patients showed Metastasis. One lesion was an epidural abscess with compression of the cord. One patients lesion was an MS Plaque. Additionally this patient presented with an Arachnoidal cyst. The lesions could be classified into 3 types according to the fiber course. In Type 1 (n=14) fibers did not pass through the lesion. In Type 2 (n=8) some fibers crossed the lesion, but most of the lesion volume did not contain fibers. In Type 3 (n=10) the fibers were completely encased by tumor. 20 tumors were considered resectable.Conclusion:These preliminary data suggest that DTI of spinal cord tumors can be capable of showing the effect of tumors on the cord with more sensitivity than conventional MRIand thus having the potential of predicting the resectability.Further prospective studies are needed to confirm these results and effects on patient outcome.
Intraoperative identification of the corticospinal tract and dorsal column of the spinal cord by electrical stimulation
Aims: Anatomical identification of the corticospinal tract (CT) and the dorsal column (DC) of the exposed spinal cord is difficult when anatomical landmarks are distorted by tumour growth. Neurophysiological identification is complicated by the fact that direct stimulation of the DC may result in muscle motor responses due to the centrally activated H-reflex.
This study aims to provide a technique for intraoperative neurophysiological differentiation between CT and DC in the exposed spinal cord.
Methods: Recordings were obtained from 32 consecutive patients undergoing spinal cord tumour surgery from 07/2015–03/2017. A double train stimulation paradigm with an intertrain interval of 60ms was devised with recording of responses from limb muscles.
Results: In non-spastic patients (55% of cohort) an identical second response was noted following the first CT response, but the second response was absent after DC stimulation. In patients with preexisting spasticity (45%), CT stimulation again resulted in two identical responses, whereas DC stimulation generated a second response that differed substantially from the first one. The recovery times of interneurons in the spinal cord grey matter were much shorter for the CT than those for the DC. Therefore, when a second stimulus train was applied 60ms after the first, the CT-fibre interneurons had already recovered ready to generate a second response, whereas the DC interneurons were still in the refractory period.
Conclusions: Mapping of the spinal cord using double train stimulation allows neurophysiological distinction of CT from DC pathways during spinal cord surgery in patients with and without preexisting spasticity.
Ultrasonographic Features of Focal Cortical Dysplasia and their Relevance for Surgical Treatment of Epilepsy
Surgery has shown to be the best therapeutic option for medically refractory cases of FCD-associated epilepsy. Seizure outcome primarily depends on the extent and completeness of resection, making intraoperative visualization and delineation of FCDs essential. Our study assesses the diagnostic yield of intraoperative ultrasound (IOUS) for such lesions.
15 consecutive patients with therapy-refractory epilepsy undergoing IOUS-assisted microsurgical resection of a radiologically suspected FCD were prospectively followed between January 2013 and July 2016. Morphological appearance on IOUS was compared to preoperative postprocessed MRI and the sonographic characteristics were analysed in relation to histological subtype. IOUS was studied in regard to its value to improve completeness of resection and improve postoperative seizure outcome.
In all cases of FCD the surgeon was able to identify the dysplastic area. Visualization of FCD I proved to be more difficult than FCD II and demarcation of its borders were less clear, resulting in residual dysplasia on postoperative coregistered MRI in two out of three patients. In every case of FCD type II, IOUS allowed clear intraoperative visualization and demarcation with high topographical-morphological correlation to preoperative postprocessed MRI. Postoperative MRI showed complete resection in every case of FCD II. Sonographic features and their severity correlate to the underlying histological degree of dysplasia (FCD IA / FCD IB < FCD IC < FCD IIA < FCD IIB). In one patient IOUS showed features atypical for FCD, which proved to be nonspecific gliosis on later histological analysis.
The distinct sonographic features on IOUS allow for intraoperative differentiation between FCD and non-FCD lesions as well as discrimination between the different histological subtypes of FCD. Sonographic demarcation depends on the underlying degree of dysplasia. IOUS allows for more tailored and improved extent of resection by clearly delineating the dysplastic area, which in turn correlates with favorable seizure outcome.
Burr hole trepanation for chronic subdural hematomas: is surgical education safe?
Aim: To investigate the safety and efficacy of surgical education for neurosurgical residents in the evacuation of chronic subdural hematomas (cSDH) by burr hole trepanation.
Methods: This is a retrospective analysis of prospectively collected data on consecutive patients receiving burr hole trepanation for uni- or bilateral cSDH. Patients operated by a supervised neurosurgery resident (teaching cases) were compared to patients operated by a board-certified faculty neurosurgeon (BCFN; nonteaching cases). The primary endpoint was surgical revision for any reason until last follow-up. The secondary endpoint was occurrence of any complication until last follow up. Clinical status, type of complications, mortality, length of surgery (LOS) and hospitalization (LOH) were tertiary endpoints.
Results: A total of n=253 cases were analyzed, of which n=217 (85.8%) were teaching and n=36 (14.2%) nonteaching cases. The study groups were balanced in terms of age, sex, surgical risk (ASA score) and preoperative status (Karnofsky Performance Scale (KPS), modified Rankin Scale (mRS), National Institute of Health Stroke Scale (NIHSS)). The cohort was followed for a mean of 242 days (standard deviation 302). In multivariate analysis, teaching cases were as likely as nonteaching cases to require revision surgery (OR 0.65, 95% CI 0.27 – 1.59; p=0.348) as well as to experience any complication until last follow-up (OR 0.79, 95% CI 0.37 – 1.67, p=0.532). Mean LOS was about ten minutes longer in teaching cases (53.0 ± 26.1min vs. 43.5 ± 17.8 min; p=0.036), but LOH was similar. There were no group differences in clinical status, mortality and type of complication at discharge and last follow-up.
Conclusions: Burr hole trepanation for cSDH can be safely performed by supervised neurosurgical residents enrolled in a structured training program, without increasing the risk for revision surgery, perioperative complications or worse outcome.
Should primary pituitary surgery for prolactinomas be limited to selected patients with microadenomas?
AIMS Consensus guidelines recommend dopamine (DA-) agonists as the first-line approach for treating prolactinomas. Although consideration of a primary surgical approach in selected patients with microadenomas is warranted, upfront surgery in patients with macroprolactinomas remains controversial, wherefore data from studies in large cohorts are sparse. In the present audit of practice in a dedicated tertiary referral center, we therefore investigated whether tumor size impacts on the long-term control of hyperprolactinemia following primary pituitary surgery with the aim of identifying risk factors for persistent long-term hyperprolactinemia and dependence on DA-agonists.
METHODS Retrospective case-note study of prospectively collected data on patients with micro- and macroprolactinomas treated with primary pituitary surgery without prior DA-agonists. The clinical, biochemical and radiological responses to first-line surgery were analyzed. The primary endpoint was patients’ dependence of DA-agonists at last follow-up. The secondary endpoint was postoperative complications. Independent risk factors for persistent long-term hyperprolactinemia and dependence on DA-agonists were calculated using multivariate logistic regression.
RESULTS A microadenoma was noted in 46 (54%) and macroadenoma in 40 (46%) patients. Median follow-up was 80 (range, 13–408) months. Long-term prolactin levels significantly decreased in all patients, independent of the initial tumor size. Long-term remission was obtained in 82% of patients with a micro- and 75% of patients with a macroprolactinoma (p = 0.60). Control of hyperprolactinemia required DA-agonists in 26% of patients with micro- vs 48% of those with macroadenomas (p = 0.05). There was no surgical related mortality and morbidity was minimal. Cavernous sinus invasion (OR 6.2, 95% CI 1.2-31.9, p = 0.03) but not tumor size (OR 1.2, 95% CI 0.4-4.1, p = 0.72) was an independent predictor for long-term dependence on DA-agonists following primary surgery.
CONCLUSION Our data indicate that in a dedicated tertiary referral center first-line surgery is a valuable alternative not only for micro- but also for macroprolactinomas that have not infiltrated the cavernous sinus.
Long-term impact of primary medical and surgical therapy on bone mineral density in men versus women with prolactinomas
Aims: Studies on the prevalence of pathological bone mineral densities (pBMD) in large cohorts of men and women with prolactinomas treated either primary surgically or medically are scarce. In the present study, we aimed at comparing the impact of the two therapeutic approaches on bone density in both sexes.
Methods: This cohort study included all consecutive prolactinoma patients with osteodensitometric data at study entry and at long-term follow-up (≥ 12 months). BMD was assessed by dual-energy X-ray absorptiometry. The primary endpoint was the impact of either approach on the prevalence of pBMD in both sexes. The secondary endpoint was the assessment of risk factors for long-term pBMD.
Results: 100 patients (40 men, 60 women) met inclusion criteria. At baseline, men had a significantly higher prevalence of pBMD than women (28 vs 2%, p < 0.001). Primary medical therapy was considered in 47 and first-line surgery in 53 patients. Median duration of follow-up was 79 months (range 13–408 months). Long-term prolactin values significantly decreased in both groups regardless of the primary treatment, with a persistent need for DA-agonists in 75% of men compared to 42% of the women (p = 0.001). The prevalence of pBMD in men remained significantly higher than in women (37% vs 7%, p < 0.001), independent of the primary treatment strategy. Persistent hyperprolactinemia and male sex were independent risk factors for pBMD at last follow-up in prolactinoma patients.
Conclusions: The prevalence of pBMD in men remains significantly higher than in women, independent of the primary treatment strategy. Osteoporosis prevention and treatment mainly focuses on women, but bone loss in men with prolactinomas should not be underestimated. A pBMD as “end organ damage” reflects the full range of the disease and might become a surrogate marker for the severity of long-lasting hyperprolactinemia.