Kristofer Ramina

Safe Resection of Arteriovenous Malformations in Eloquent Motor Areas Aided by Functional Imaging and Intraoperative Monitoring

BACKGROUND: Arteriovenous malformations (AVMs) proximal to motor cortical areas or motor projection systems are challenging to manage because of the risk of severe sensory and motor impairment. Surgical indication in these cases therefore remains controversial. OBJECTIVE: To propose a standardized approach for centrally situated AVMs based on functional imaging and intraoperative electrophysiological evaluation. METHODS: We conducted a retrospective analysis of 15 patients who underwent surgical treatment for AVMs in motor cortical areas or proximal to motor projections. Preoperative assessment included functional magnetic resonance and 3-dimensional tractography. Operations were performed under continuous electrophysiological monitoring aided by direct brain stimulation. We identified critical bloody supply to the motor areas by temporary occluding the feeding vessels under electrophysiological monitoring. Clinical outcome was evaluated with the modified Rankin Scale. RESULTS: Total resection was achieved in 12 cases, whereas electrophysiology limited total extirpation in 3 cases. A significant reduction of motor evoked potentials by up to 15% of the initial values was associated with good recovery of motor function; in contrast, the disappearance of potentials correlated with long-term impairment. The mean follow-up time was 13 months, and clinical assessments revealed overall functional improvement (P < .05). After surgery, 11 patients were asymptomatic or presented with only minor neurological deficits. CONCLUSION: Surgical resection of AVMs in eloquent motor areas can be considered a safe option for selected cases when performed in conjunction with a detailed functional assessment. Possible selection criteria for surgical treatment are discussed in light of the presented clinical data. ABBREVIATIONS: AVM, arteriovenous malformation DSA, digital subtraction angiography DTI, diffusion tensor imaging fMRI, functional magnetic resonance imaging MEP, motor evoked potential mRS, modified Rankin Scale SEP, somatosensory evoked potential

Prophylactic nimodipine treatment for cochlear and facial nerve preservation after vestibular schwannoma surgery: a randomized multicenter Phase III trial

OBJECTIVE A pilot study of prophylactic nimodipine and hydroxyethyl starch treatment showed a beneficial effect on facial and cochlear nerve preservation following vestibular schwannoma (VS) surgery. A prospective Phase III trial was undertaken to confirm these results. METHODS An open-label, 2-arm, randomized parallel group and multicenter Phase III trial with blinded expert review was performed and included 112 patients who underwent VS surgery between January 2010 and February 2013 at 7 departments of neurosurgery to investigate the efficacy and safety of the prophylaxis. The surgery was performed after the patients were randomly assigned to one of 2 groups using online randomization. The treatment group (n = 56) received parenteral nimodipine (1-2 mg/hr) and hydroxyethyl starch (hematocrit 30%-35%) from the day before surgery until the 7th postoperative day. The control group (n = 56) was not treated prophylactically. RESULTS Intent-to-treat analysis showed no statistically significant effects of the treatment on either preservation of facial nerve function (35 [67.3%] of 52 [treatment group] compared with 34 [72.3%] of 47 [control group]) (p = 0.745) or hearing preservation (11 [23.4%] of 47 [treatment group] compared with 15 [31.2%] of 48 [control group]) (p = 0.530) 12 months after surgery. Since tumor sizes were significantly larger in the treatment group than in the control group, logistic regression analysis was required. The risk for deterioration of facial nerve function was adjusted nearly the same in both groups (OR 1.07 [95% CI 0.34-3.43], p = 0.91). In contrast, the risk for postoperative hearing loss was adjusted 2 times lower in the treatment group compared with the control group (OR 0.49 [95% CI 0.18-1.30], p = 0.15). Apart from dose-dependent hypotension (p < 0.001), no clinically relevant adverse reactions were observed. CONCLUSIONS There were no statistically significant effects of the treatment. Despite the width of the confidence intervals, the odds ratios may suggest but do not prove a clinically relevant effect of the safe study medication on the preservation of cochlear nerve function after VS surgery. Further study is needed before prophylactic nimodipine can be recommended in VS surgery.

Spectroscopy imaging in intraoperative MR suite: tissue characterization and optimization of tumor resection

BackgroundMR spectroscopy (MRS) measurements are common practice in the preoperative diagnostic regimen, but no evidence exists concerning their value in intraoperative MRI (iMRI) setting. We sought to examine the feasibility of intraoperative MRS and to assess the clinical value of the method in optimizing the gliomas resection.MethodsForty-five patients with low- and high-grade gliomas underwent iMRI-assisted surgery, including pre- and intraoperative MRS measurements. During the intraoperative control scan, MRS was performed at the resection margin. Peak areas under the major metabolites (N-acetyl-aspartate: NAA; choline: Cho; and creatine: Cr) resonances were estimated, and their ratios entered in the statistical analysis.ResultsConcerning preoperative MRS imaging, mean Cho/NAA and Cho/Cr ratios in low-grade gliomas were 2.3 and 1.2, respectively. The average Cho/NAA and Cho/Cr ratios in the high-grade gliomas were 3.9 and 2.3, respectively. In 12 out of 20 cases with low-grade gliomas, intraoperative conventional MR imaging showed suspected tumor remnant and MRS diagnosed correctly the tissue signal alterations in 10 out of those 12 cases. MRS could characterize gadolinium-enhancing or non-enhancing tumor remnants in all cases with high-grade tumors. Thus, it could help achieve total tumor resection unless the latter was contraindicated due to increased risk of neurological complications.ConclusionsMR spectroscopy (MRS) in an iMRI setting is feasible, facilitating preoperative glioma staging as well as satisfactory characterization of suspected tumor remnants. Thus, it may be helpful tool for an extended tumor resection.

Surgery of cavernous hemangioma of the optic nerve: case report and review.

A case of a cavernous hemangioma of the optic nerve is presented. Cavernous malformations of the cranial nerves are quite rare and have been reported to involve the third nerve, the seventh nerve in the temporal bone, the seventh and the eighth nerves in the internal auditory canal as well as the optic chiasm and optic nerve. We present a case of a patient with a cavernous hemangioma within the right optic nerve, which could be removed by microsurgery with preservation and improvement of vision. Literature on this rare location of cavernoma is reviewed.

Spinal metastasis of endometrial stromal sarcoma: Clinicopathological features and management

BACKGROUND Endometrial Stromal Sarcoma (ESS) is a rare uterine malignancy which often metastasizes several years after initial diagnosis. Thoracic spine is a rare ESS metastatic site and its proper management is still not a consensus. We discuss the histopathological features and the management strategies through an illustrative case of a 77 year-old woman with metastasis to the thoracic spine 13 years after total hysterectomy for ESS. METHODS Review of the literature and identification of 5 patients, including our present case, with ESS involving the spinal cord. We discuss the outcomes achieved after each therapy. In our case, the patient presented a mass involving the thoracic spinal canal constricting the spinal cord at T7 level. A two-level decompression laminectomy was performed and the lesion was partially excised. RESULTS The histopathological along with the immunohistochemical profile mitotic rate indicated the endometrial stromal cells origin of the tumor, confirming the diagnosis of a low-grade ESS metastasis. The patient was managed with surgery in combination with postoperative radiation therapy. CONCLUSIONS The small number of published cases precludes definitive conclusions regarding standard management. However, it seems that treatment of metastatic ESS to the spine matches the same general concepts of spine metastasis, namely surgery followed by radiation therapy, due to clinical improvement and long-term disease control of the reported cases. Hormonal therapy may be considered in recurrent disease with strong expression of estrogen and progesterone receptors. However, these findings need confirmation in larger studies.

Prophylactic nimodipine treatment and improvement in hearing outcome after vestibular schwannoma surgery: a combined analysis of a randomized, multicenter, Phase III trial and its pilot study

OBJECTIVE In clinical routines, neuroprotective strategies in neurosurgical interventions are still missing. A pilot study (n = 30) and an analogously performed Phase III trial (n = 112) pointed to a beneficial effect of prophylactic nimodipine and hydroxyethyl starch (HES) in vestibular schwannoma (VS) surgery. Considering the small sample size, the data from both studies were pooled. METHODS The patients in both investigator-initiated studies were assigned to 2 groups. The treatment group (n = 70) received parenteral nimodipine (1-2 mg/hour) and HES (hematocrit 30%-35%) from the day before surgery until the 7th postoperative day. The control group (n = 72) was not treated prophylactically. Facial and cochlear nerve functions were documented preoperatively, during the inpatient care, and 1 year after surgery. RESULTS Pooled raw data were analyzed retrospectively. Intent-to-treat analysis revealed a significantly lower risk for hearing loss (Class D) 12 months after surgery in the treatment group compared with the control group (OR 0.46, 95% CI 0.22-0.97; p = 0.04). After exclusion of patients with preoperative Class D hearing, this effect was more pronounced (OR 0.38, 95% CI 0.17-0.83; p = 0.016). Logistic regression analysis adjusted for tumor size showed a 4 times lower risk for hearing loss in the treatment group compared with the control group (OR 0.25, 95% CI 0.09-0.63; p = 0.003). Facial nerve function was not significantly improved with treatment. Apart from dose-dependent hypotension (p < 0.001), the study medication was well tolerated. CONCLUSIONS Prophylactic nimodipine is safe and may be recommended in VS surgery to preserve hearing. Prophylactic neuroprotective treatment in surgeries in which nerves are at risk seems to be a novel and promising concept. Clinical trial registration no.: DRKS 00000328 ( https://drks-neu.uniklinik-freiburg.de/drks_web/ ).

Interobserver variability of the House-Brackmann facial nerve grading system for the analysis of a randomized multi-center phase III trial

BackgroundEvidence of a high interobserver variability of the subjective House-Brackmann facial nerve grading system (HBGS) would justify cost- and time-consuming technological enhancements of objective classifications for facial nerve paresis.MethodA total of 112 patients were recruited for a randomized multi-center trial to investigate the efficacy of prophylactic nimodipine treatment in vestibular schwannoma (VS) surgery. For the present investigation both treatment groups were pooled for the assessment of facial nerve function preoperatively, in the early postoperative course and 1 year after the surgery. Facial nerve function was documented photographically at rest and in motion and classified according to the HBGS by three independent observers (neurosurgeon, neurologist, ENT) and by the investigator of each center.ResultsInterobserver variability was considerably different with respect to the three time points depending upon the severity of facial nerve paresis. Preoperative facial nerve function was normal or only mildly impaired (HB grade I or II) and was assessed consistently in 97%. Facial nerve function deteriorated during the early postoperative course and was subsequently documented without dissent in only 36%, with one grade difference in 45%, two grade difference in 17% and three grade difference in 2%. One year after surgery, facial nerve function predominantly improved resulting in a consistent assessment in 66%. Differing ratings were observed in 34% with one grade deviation in 88% and of two grades in 12%. Patients with differing ratings of two or more grades exhibited considerably worse facial nerve function (p < 0.001).ConclusionsThe HBGS produced comparable results between different observers in patients with normal or only mildly impaired facial nerve function. Interobserver variability increased depending on the severity of facial nerve paresis. The results suggest that the HBGS does not promote uniformity of reporting and comparison of outcomes in patients with moderate or severe facial nerve paresis.

MRI-based radiation-free method for navigated percutaneous radiofrequency trigeminal rhizotomy.

UNLABELLED BACKGROUND/STUDY AIMS: Percutaneous radiofrequency trigeminal rhizotomy (RTR) is a standardized treatment for trigeminal neuralgia, yet it has been associated with serious complications related to the cannulation of the foramen ovale. Some of these complications, such as carotid injury, are potentially lethal. Neuronavigation was recently proposed as a method to increase the procedures safety. All of the techniques described so far rely on pre- or intraoperative computed tomography scanning. Here we present a simple method based on magnetic resonance imaging (MRI) (radiation free) used to target the foramen ovale under navigation guidance. PATIENTS/MATERIAL AND METHODS We retrospectively analyzed nine patients who had undergone navigated percutaneous RTR based solely on preoperative MRI and compared them with 35 patients who underwent conventional RTR guided by fluoroscopy. We analyzed immediate and late outcome and categorized the results into pain free, > 70% pain reduction, and persistent pain. We also compared groups in terms of the duration of the procedure and the complication rates. Here we describe the navigation method in detail and review the anatomical landmarks for target definition. RESULTS The duration of the surgical procedure was similar in both groups (32.1 in the standard technique versus 34.5 minutes with navigation; p = 0.5157). There was no significant difference between groups regarding pain reduction at the immediate (p = 1.0) or late follow-up (p = 0.6284) time points. Furthermore, no serious complications were observed in the navigated group. CONCLUSIONS We present a simple radiation-free method for neuronavigation-assisted percutaneous RTR. This method proved to be safe and effective, and it is especially recommended for young, inexperienced neurosurgeons.