Lasse Dührsen

Minimally invasive approach for small ventrally located intradural lesions of the craniovertebral junction

OBJECT The surgical management of lesions ventral to the neuraxis at the level of the craniovertebral junction (CVJ) and upper cervical spine is challenging. Here, the authors describe a minimally invasive dorsal approach for small ventrally located intradural lesions at the CVJ as an alternative for the more extensive classic transoral approach or variants of suboccipital approaches. METHODS Between 2012 and 2014, 6 symptomatic patients with a small lesion of the ventral aspect at the CVJ level were treated using a minimally invasive dorsal approach at the University Medical Center in Hamburg-Eppendorf, Germany. The anatomical distance between the posterior atlantooccipital membrane and the posterior atlantoaxial ligament, as determined by CT images, was assessed in the treated patients and in 100 untreated persons. RESULTS The authors treated 6 patients (mean age 54.7 years) who had a clinical presentation of mild neurological symptoms that disappeared after resection. Minimally invasive surgical dorsal access was achieved by using tubular systems and using the natural space between the occiput (C-0) and C-1, and in 1 case between C-1 and C-2, without having to remove bony structures. The postoperative course in each of the 6 patients was uneventful. The neuropatho-logical findings confirmed a meningotheliomatous meningioma (WHO Grade I) in 5 cases and an extramedullary cavernous hemangioma in 1 case. MRI confirmed complete resection of all the lesions. The atlantooccipital distances ranged from 3 to 17 mm (mean 8.98 mm) in the supine neutral position, and the atlantoaxial distances ranged from 5 to 17 mm (mean 10.56 mm). There were no significant differences between women and men (atlantooccipital p = 0.14; atlantoaxial p = 0.72). CONCLUSIONS The results of this study demonstrate that the minimally invasive dorsal approach using the space between C-0 and C-1 or C-1 and C-2 provides direct and sufficient exposure for the safe surgical resection of small ventrally located intradural lesions at the CVJ level while reducing the necessity for musculoskeletal preparation to a minimum.

A novel threshold criterion in transcranial motor evoked potentials during surgery for gliomas close to the motor pathway

OBJECTIVE Warning criteria for monitoring of motor evoked potentials (MEP) after direct cortical stimulation during surgery for supratentorial tumors have been well described. However, little is known about the value of MEP after transcranial electrical stimulation (TES) in predicting postoperative motor deficit when monitoring threshold level. The authors aimed to evaluate the feasibility and value of this method in glioma surgery by using a new approach for interpreting changes in threshold level involving contra- and ipsilateral MEP. METHODS Between November 2013 and December 2014, 93 patients underwent TES-MEP monitoring during resection of gliomas located close to central motor pathways but not involving the primary motor cortex. The MEP were elicited by transcranial repetitive anodal train stimulation. Bilateral MEP were continuously evaluated to assess percentage increase of threshold level (minimum voltage needed to evoke a stable motor response from each of the muscles being monitored) from the baseline set before dural opening. An increase in threshold level on the contralateral side (facial, arm, or leg muscles contralateral to the affected hemisphere) of more than 20% beyond the percentage increase on the ipsilateral side (facial, arm, or leg muscles ipsilateral to the affected hemisphere) was considered a significant alteration. Recorded alterations were subsequently correlated with postoperative neurological deterioration and MRI findings. RESULTS TES-MEP could be elicited in all patients, including those with recurrent glioma (31 patients) and preoperative paresis (20 patients). Five of 73 patients without preoperative paresis showed a significant increase in threshold level, and all of them developed new paresis postoperatively (transient in 4 patients and permanent in 1 patient). Eight of 20 patients with preoperative paresis showed a significant increase in threshold level, and all of them developed postoperative neurological deterioration (transient in 4 patients and permanent in 4 patients). In 80 patients no significant change in threshold level was detected, and none of them showed postoperative neurological deterioration. The specificity and sensitivity in this series were estimated at 100%. Postoperative MRI revealed gross-total tumor resection in 56 of 82 patients (68%) in whom complete tumor resection was attainable; territorial ischemia was detected in 4 patients. CONCLUSIONS The novel threshold criterion has made TES-MEP a useful method for predicting postoperative motor deficit in patients who undergo glioma surgery, and has been feasible in patients with preoperative paresis as well as in patients with recurrent glioma. Including contra- and ipsilateral changes in threshold level has led to a high sensitivity and specificity.

Neuropsychological performance and seizure control after subsequent anteromesial temporal lobe resection following selective amygdalohippocampectomy

Selective amygdalohippocampectomy (sAHE) is a well‐established treatment for temporal lobe epilepsy, commonly with favorable neuropsychological outcome. Yet, it is still unknown if subsequent resection of the anteromesial temporal lobe (AMTLR), when necessary, deteriorates neuropsychological performance in this selected group of patients. Thus, we evaluated the clinical and neuropsychological data of patients who, due to insufficient seizure control after sAHE, received a subsequent ipsilateral AMTLR and compared these findings with patients who did not receive a second resection (control group).

Basilar impression as complication of Grisel's syndrome

Grisels syndrome presents a rare disease. Here, we present a peculiar case of Grisels syndrome with an unfavorable course developing a basilar impression. This highlights the importance of close clinical and radiological follow‐up even in cases where the course seems uncomplicated.

Influence of antithrombotic agents on recurrence rate and clinical outcome in patients operated for chronic subdural hematoma

INTRODUCTION Chronic subdural hematoma (cSDH) is a common pathology encountered in neurosurgical practice, especially in elderly patients, who frequently require antithrombotic agents. The aim of this study was to investigate the influence of antithrombotic agents on recurrence rates and clinical outcomes in patients operated for cSDH. METHODS A cohort of patients operated for cSDH at one center during a 5 years period was analyzed retrospectively. Presenting symptoms, coagulation testing, history of antithrombotic agents and comorbidities were obtained from the patient charts. The standard neurosurgical procedure was a single burr hole under local anesthesia with insertion of a subdural drainage. Questionnaires and telephone interviews were used to assess the clinical outcome using the modified Rankin Scale (mRS). Good outcome was defined as mRS 0 to 3 and poor outcome as mRS 4 to 6. RESULTS 201 patients with cSDH underwent initial surgical treatment and were enrolled in the study. The median follow-up was 81 weeks. 41 patients (20.4%) were on antiplatelet drug and 43 (21.4%) were on phenprocoumon. A recurrent hematoma required surgery in 37 patients (18.4%). A poor outcome was seen in 36 patients (17.9%). Each of older age and administration of phenprocoumon at admission was an independent risk factor predictive of poor outcome, (p=0.001 and p=0.031, respectively)) Administration of antithrombotic agents had no impact on hematoma recurrence. CONCLUSION Administration of phenprocoumon and older age might increase the risk of poor outcome in patients with cSDH. Neither the administration of phenprocoumon nor antiplatelet drug influenced the recurrence rate of subdural hematoma in our patient cohort.

A 55-Year-Old Woman with Year-Long Headache and Dizziness: Correspondence

A 55-year-old woman presented with headaches and dizziness for one and a half years. An initial lumbar puncture and MRI showed no relevant results. In the meantime, she experienced intermittent nausea and vomiting with significant weight loss. Shortly before she was referred to our institution she had for the first time a generalized seizure. A MRI scan now showed FLAIR-signal intense arachnoidea and partial diffuse contrast enhancement in the left central sulcus and sylvian fissures bilaterally as well as cerebral and spinal leptomeningeal enhancement (Figure 1A,B). There were no parenchymal lesions. A biopsy of one of the contrast enhancing parts of arachnoidea was planned. Unexpectedly, after opening the dura mater, it was noted that the cerebral surface was covered by densely pigmented black tissue. Three cortical biopsies were taken. PATHOLOGY

Meninigiomas of the Craniocervical Junction--A Distinctive Subgroup of Meningiomas.

Objective Meningioma of the cranio-cervical junction is a rare diagnosis and demand a thorough surgical planning as radical excision of these tumors is difficult. In this context recurrence is most likely due to regrowth of residual tumor. The aim of this study was to evaluate the clinical course of patients operated for craniocervical meningioma (CCM) and to investigate the histological features of these tumors and their impact on recurrence rate. Methods All patients who were operated for CCM at our institution between 2003 and 2012 were identified. Presenting symptoms, MRI findings, surgical approaches and recurrence rate were reviewed retrospectively using medical charts. Histological features of the included tumors were studied focusing on subtypes and MIB-1 immunoreactivity and compared with MIB-1 immunoreactivity in an age and gender-matched control group of patients with supratentorial meningioma. Results 18 patients with CCM with a mean age of 56.2 years and median follow-up of 60 months were included in the study. Sensory or motor deficit was the most frequent presenting symptom followed by neck pain and lower cranial nerve palsy. Simpson grade II resection was achieved in 16 patients and Simpson grade III resection in two patients. Mortality, morbidity and recurrence rates were 16.7%, 5.5% and 5.5%, respectively. According to the WHO-grading all were found to be grade I meningiomas. Histological subtypes included meningotheliomatous (10), transitional (2), fibrillar (2), angiomatous (3) and secretory (1) meningioma. The mean MIB-1 labeling index in the study group was significantly higher than in the control group, (7.2% and 3.6%, respectively), p < 0.05. There was no correlation between MIB-1 levels and tumor recurrence. Conclusions CCM seems to have a benign character. Despite a significantly higher MIB-1 index, a high rate of recurrence was not observed. Therefore, approaches with high morbidity are not justified. Nevertheless, in view of the challenging approaches with limited access to the lesion, CCM should be considered a distinctive clinical subgroup.