Martin Strowitzki

Ultrasound-based navigation during intracranial burr hole procedures: experience in a series of 100 cases.

BACKGROUND To establish a rational basis for intraoperative ultrasound guidance in neurosurgical procedures via a single burr hole approach based on the experience of one hundred cases. METHODS The single burr hole approach is carried out using a bayonet-shaped ultrasound transducer with a tip dimension of 8 x 8 mm. The ultrasound probe with a mounted puncture adapter fits a standard burr hole and allows real-time imaging of the ongoing surgical steps. RESULTS One hundred cases with five indications have been operated on so far: tapping of the ventricular system (46 patients), tapping of intracranial cysts (23 patients), biopsy of intracranial tumors (15 patients), evacuation of intracranial abscesses (9 patients), and evacuation of intracerebral hematomas (7 patients). Depending on their size, the ventricles could be clearly visualized in 34 of 46 patients. In the remaining patients the free margin of the falx served as orientation. Two ventricles could neither be visualized nor entered. Visualization and puncture of intracranial cysts were easy to achieve throughout, as was the case with abscesses. Tumor biopsy was unsuccessful in two patients harboring lymphomas at distances of more than 50 mm from probe to target. Intracerebral hematomas were easily visualized but, due to the presence of clots, aspiration was impossible in two patients. One patient with a giant glioblastoma died the day after the uneventful biopsy due to increased cerebral edema. No other complications occurred. CONCLUSIONS The presented method of ultrasound-based neuronavigation is an easy-to-use, fast, and safe technique of real-time imaging for free-hand single burr hole procedures.

Gravitational Shunts in Longstanding Overt Ventriculomegaly in Adults

OBJECTIVE:A new entity of chronic hydrocephalus was introduced recently in the international literature: longstanding overt ventriculomegaly in adults. Previous experience with this disorder has demonstrated that shunt therapy for such patients involves a considerable risk of overdrainage. In the present study, we aimed to clarify whether this risk could be avoided by use of gravitational shunts. METHODS:A total of 26 adults (age range, 17–75 yr) with macrocephaly and progressive hydrocephalus symptoms underwent implantation of either an adjustable Codman Hakim gravity-assisted shunt (Codman Medos, LeLocle, Switzerland) plus an Aesculap-Miethke ShuntAssistant (Miethke KG, Kleinmachnow, Germany) or a nonadjustable gravitational shunt (Aesculap-Miethke gravity-assisted valve). The follow-up period averaged 29 ± 13 months (range, 6–48 mo). RESULTS:Significant sustained clinical improvement was achieved in 87% of patients. In more than 90% of patients, Evans index decreased postoperatively by less than 10%. No correlation was documented between the degree of ventricle width reduction and clinical improvement. Only two patients developed subdural hematoma, which was caused by insufficient hydrostatic pressure compensation owing to errors in estimation of intraperitoneal pressure. CONCLUSION:Unlike conventional differential pressure shunts, gravitational shunts can be used in the treatment of high-risk patients with longstanding overt ventriculomegaly in adults. Significant risk of overdrainage can be avoided. Gravitational shunts offer a viable alternative to endoscopic third ventriculostomy, provided the choice and adjustment of the shunt opening pressure is based on a correct assessment of the hydrostatic pressure to be compensated for.

Accuracy of ultrasound-guided puncture of the ventricular system

ObjectsPuncture of the ventricular system as one of the most frequently performed operative procedures in neurosurgery is usually done in a freehand way without guiding devices. The objective of this study is to examine whether ultrasonic guidance is able to heighten the accuracy of ventricular tapping.MethodsReal-time imaging via a single burr hole approach is achieved by aid of a bajonet-like shaped transducer with a footprint of 8x8 mm only (EUP-NS32, Hitachi Medical Systems). The needle is advanced towards the frontal horn along a displayed guideline. 51 punctures in 48 patients were performed with ultrasonic guidance and compared to 85 punctures in 67 patients without a guiding device.ConclusionThe presented ultrasound method was not able to heighten the access rate of ventricular tapping, but it improved correct positioning of the catheter tip inside the frontal horn of the ventricular system significantly.

Gravitational shunt management of long-standing overt ventriculomegaly in adult (LOVA) hydrocephalus

OBJECTIVES Recently a new subtype of chronic hydrocephalus was described: long-standing overt ventriculomegaly in adults (LOVA). Experience to date has indicated that shunt therapy was contraindicated, due to over-drainage. Therefore we investigated whether this problem could be overcome using gravitational shunts. MATERIALS AND METHODS Thirty macrocephalic adults (17-72 years of age), suffering from progressive hydrocephalus were managed with two different gravitational shunts. The post-operative observation period was 5-87 months. RESULTS Only two patients developed hygromas, and only one of these required surgical shunt revision. Eighty-seven percent of patients had a long-lasting clinical improvement. Ventricular size was only slightly reduced in 29 patients. There was no correlation between reduction in ventricular size and clinical improvement. CONCLUSION Contrary to clinical guidelines issued to date, we demonstrate that LOVA can be treated reliably with gravitational shunts, making them a genuine alternative to endoscopic third ventriculostomy (ETV).

Nasoethmoidal Meningioma with Cytogenetic Features of Tumor Aggressiveness in a 16-Year-Old Child

The case of a 16-year-old girl is presented who was admitted to our hospital because of severe frontal headache. Magnetic resonance scans revealed a nasoethmoidal tumor on the right side, with erosion of the skull base and invasion of the right orbit. A needle biopsy specimen revealed the histological diagnosis of a fibroblastic meningioma (WHO grade II), with histochemically determined partial activity loss of alkaline phosphatase. The tumor was completely resected by a combined intracranial-transbasal and transnasal approach. In this case, we found a meningioma with deletion of the short arm of chromosome 1 through a translocation between chromosomes 1 and 11 [t(1;11)] as well as additional chromosomal aberrations, including partial or complete monosomy of chromosomes 2, 6, 7, 11, 13 and 22, a cytogenetic pattern known to be associated with elevated tumor aggressiveness in meningiomas of adult patients. Accordingly, this juvenile meningioma may biologically correspond to a WHO grade II adult-type meningioma with an increased risk of recurrence. Therefore, we incorporated this patient into an intensified schedule of postoperative care.

Prognostic value of SSEP in early aneurysm surgery after SAH in poor-grade patients.

Abstract We evaluate the prognostic value of somatosensory evoked potentials (SSEP) in poor-grade patients after early surgery for aneurysmal subarachnoid hemorrhage compared to the Hunt and Hess (H&H) and WFNS scales. Ninety patients with angiographically proven aneurysms graded H&H IV or V were evaluated retrospectively. The aneurysms of 72 patients were clipped. In 53 out of 72 patients 147 SSEP examinations were recorded. The SSEP were classified according to the central conduction time (CCT) and the number of cortical potentials. Outcome was determined according to the Glasgow Outcome Scale. To evaluate the predictability of the SSEP to clinical grading scales receiver operating characteristic (ROC) analysis was done. The H&H scale did not demonstrate statistically significant predictability for poor-grade patients. The WFNS scale predicted the outcome for only one group (survival/death) (p = 0.035). Predictability of outcome by the SSEP was statistically confirmed. Normal CCT indicated a potential for a good recovery, but not consistently so. Bilaterally enhanced CCT was predictive of a poor outcome. Bilateral lack of cortical responses was always related to fatal outcome. ROC analysis confirmed that SSEP are superior to clinical grading scales in determining prognosis in poor-grade patients. In doubt, whether early aneurysm surgery or conservative treatment in a poor-grade patient should be done, SSEP will be helpful.

Vertex Epidural Hematoma with Communicating Bifrontal Subgaleal Hematomas Treated by Percutaneous Needle Aspiration

The case of an 11-year-old boy is presented who suffered a bicycle accident with a parasagittal skull fracture, a small vertex epidural hematoma, frontal contusions and a frontal subgaleal hematoma. Enlargement of the vertex epidural hematoma was diagnosed after development of a slight paraparesis on day 11 with the aid of MRI. Three percutaneous needle aspirations of the subgaleal hematoma with a total of 59 ml being evacuated led to quick recovery and disappearance of the subgaleal as well as the vertex epidural hematoma. It is speculated that both hematomas communicated via the skull fracture thus making the evacuation of the epidural hematoma by subgaleal punctures possible.

Identification of somatosensory pathways by focal-cooling-induced changes of somatosensory evoked potentials and EEG-activity--an experimental study.

Summary Object. Function-preserving neurosurgery requires methods to identify functionally important CNS-areas intraoperatively. We investigated whether a combination of focal cerebro-cortical cooling and monitoring of somatosensory evoked potentials (SEP) is suited for this task, i.e. whether it is able to outline structures belonging to the somatosensory pathway. Methods. In 17 Wistar rats the somatosensory cortex was focally cooled by 20°C below the initial tissue temperature for periods of five minutes. A cryoprobe with a tip diameter of 3 mm was used and tissue temperatures were measured below and at different distances to the cryoprobe. Tibial nerve evoked SEPs and EEG-spectra were recorded continuously. Results. During cortical cooling the SEP-responses showed a marked delay and amplitude increase of the cortically generated components P13 and N18 and a small latency increase of the subcortically generated wave III. EEG-spectra were depressed mainly in the low frequency range. All cooling effects were reversible and in light- as well as electron-microscopic examinations no tissue damage was found. Conclusions. Focal cooling of the cortex induces easily recognizable and reversible changes of the bio-electrical activity without causing any histological damage. Therefore the method seems suitable for identifying eloquent areas. It can be expected that clinical application of the cooling technique in combination with intraoperative electrophysiological monitoring will be helpful to further lower the risk of neurosurgical operations. We propose that cooling mainly interferes with the synaptic transmission within the somatosensory cortex, because the observed amplitude increase can be explained by cold-induced depression of inhibitory cortical activity (disinhibition).

Transcranial color-coded sonography of a vein of Galen arteriovenous malformation in an adult.

The case of an adult harboring a vein of Galen arteriovenous malformation (VGAM) is reported. Diagnosis was established by computed tomography (CT) and digital subtraction angiography and confirmed afterwards by transcranial color‐coded sonography (TCCS). The patients course after endovascular treatment was then consecutively monitored by TCCS until complete occlusion was achieved. The results of TCCS were validated by angiography, with which they showed good correlation. Thus, it can be concluded that TCCS may be a useful adjunct to CT and angiography to noninvasively monitor adults with VGAM.

Acute hydrocephalus as a late complication of hemispherectomy.

SummaryTwo cases of acute hydrocephalus 34 and 27 years after hemispherectomy are presented. Both were examined by intracranial pressure recordings and treated with shunting procedures. The recordings gave evidence of raised baseline values of intracranial pressure and showed pathological B-wave activity in over 80% of the recording time.The problem of free communication between the different compartments after hemispherectomy and different surgical approaches to solve the problem are discussed. Open surgery is not advocated.