Hans E. Heissler

Multiple microsurgical resections for repeated recurrence of glioblastoma multiforme.

Objectives:There has been little evidence so far supporting further surgical intervention in case of repeated recurrence of glioblastoma multiforme (GBM). Thus, the efficacy and utility of repeated resection remains unclear but worthy of consideration. The aim of this study was to review the efficacy of multiple repeated resections in patients with recurrent GBM. Methods:Forty-two patients underwent repeated surgical resections for recurrent GBM. All patients who underwent >2 surgical interventions were clustered in group A. Group B were patients treated nonsurgically after resection of the first recurrence. Patients’ treatment history, including surgical interventions, radiotherapy, chemotherapy regimens, postoperative complications, Karnofsky Performance Score, and survival rate were reviewed. Results:Group A consisted of 10 patients (median age, 60.5 y) and group B of 32 patients (median age, 56.5 y). Histopathologic findings revealed typical GBM in 8 patients of group A and in 23 patients of group B. An oligodendroglial component was detected in 2 patients of group A and in 7 patients of group B. The median Karnofsky Performance Score after the first surgery for tumor recurrence was 80 in both groups (P=0.084). The median overall survival time was 26 months in patients of group A and 16 months in patients of group B (P=0.052). The 2-year survival rate of group A was 58.3% and significantly higher than in group B (29.0%; P=0.036). The 3-year survival rate of group A was 31.1% and 12.4% of group B (P=0.038). Conclusions:Microsurgical resection of repeatedly recurring GBM is likely to prolong survival. Repeated surgical resection may be considered as an effective treatment option in addition to radiochemotherapy in repeated GBM recurrence.

Deep brain stimulation of the pedunculopontine tegmental nucleus modulates neuronal hyperactivity and enhanced beta oscillatory activity of the subthalamic nucleus in the rat 6-hydroxydopamine model.

Deep brain stimulation (DBS) of the pedunculopontine nucleus (PPN) area has been introduced as a novel surgical therapy for dopamine refractory gait problems, freezing and postural instability in the late stage of Parkinsons disease (PD). Lesions of the pedunculopontine tegmental (PPTg) nucleus, the equivalent of the PPN in rodents, were shown to reduce the elevated discharge rate of the subthalamic nucleus (STN) in the 6-hydroxydopamine (6-OHDA) rat model of PD. In order to further elucidate the modulatory effect of the PPTg on the STN we examined the effect of 25 Hz low frequency PPTg stimulation on neuronal single unit activity and oscillatory local field potentials (LFPs) of the STN, and on the electrocorticogram (ECoG) of the primary motor cortex region in rats with unilateral 6-OHDA induced nigrostriatal lesions. Stimulation of the PPTg reduced the enhanced firing rate in the STN, without affecting the firing pattern or approximate entropy (ApEn). It also reduced the activity in the beta band (15-30 Hz) of the STN, which is elevated in 6-OHDA lesioned rats, without affecting beta activity in the motor cortex. We showed a modulatory effect of PPTg stimulation on altered neuronal STN activity in the PD 6-OHDA rat model, indicating that PPTg DBS may alter activity of the basal ganglia circuitry at least partially. It remains unclear, however, how these changes are exactly mediated and whether they are relevant with regard to the descending PPTg projections in the lower brainstem.

Vestibular schwannoma microsurgery for recurrent tumors after radiation therapy or previous surgical resection.

Objective The purpose of this study is to compare the outcomes in patients who underwent microsurgical resection for recurrent vestibular schwannoma after microsurgical resection and previous radiation therapy. Study Design Retrospective study. Setting University hospital. Patients Fifteen patients, who underwent microsurgical resection for recurrent vestibular schwannoma after previous surgery (group A), and 5 patients, who underwent microsurgical resection after previous radiation therapy (group B) were included. Intervention Surgical resection after radiation therapy or previous surgical resection. Main Outcome Measures Intraoperative findings and postoperative facial nerve function were investigated in groups A and B. Results Mean tumor volumes were 18.4 ± 2.44 cm3 in group A and 19.0 ± 1.53 cm3 in group B. Total resection was achieved in 10 patients (67%) of group A and in 3 patients (60.0%) of group B. The tumor was more difficult to resect because of severe adhesions to the facial nerve. Anatomic facial nerve preservation could be achieved in 19 patients. Mean follow-up time was 80 months for group A and 28 months for group B. At last follow-up, 7 patients (53.8%) of group A had a good facial nerve function. In 3 patients (75.0%) of group B, the preoperative facial nerve function was preserved postoperatively. Preexistent facial paresis, large tumor with extrameatal growth and brainstem compression correlated with poor postoperative facial nerve function. Conclusion Surgical outcome of recurrent vestibular schwannoma is more unsatisfactory than after primary surgery. It remains to be clarified whether previous surgery may implicate a higher risk for postoperative facial nerve function than previous radiation therapy upon surgery for tumor recurrence.

Chronic cerebrovascular insufficiency on the xenon CT scan

Several investigators have describedCT-negative low flow areas in TIA and stroke patients in the chronic phase. The emission tomographic SPECT image they employed has, in contrast to the xenon CT method, no direct relation to the x-ray transmission CT scan. The aim of our study was to study the phenomenon ofCT-negative low flow areas using the xenon CT method, a method especially well suited for such cases. 57 xenon CT examinations were performed in 40 TIA patients, and 56 xenon CT examinations in 32 stroke patients. Flow data from brain tissue which appeared to be anatomically intact in a slice 5 cm above the canthomeatal plane were analyzed. In the TIA group, the flow in the gray matter was found to be significantly lower on the clinically affected side: symptomatic side, 61.8 ± 14.7 ml/100 g/min; asymptomatic side, 66.4 ± 15.8 ml/100 g/min (p < 0.001).In the stroke group, the flow in the white matter was also affected; symptomatic side, 31.2 ± 9.8 ml/100 g/min; asymptomatic side, 35.3 ± 11.1 ml/100 g/min (p < 0.01). Gray matter: symptomatic side, 56.1 ± 11.4 ml/100 g/min; asymptomatic side, 66.0 ± 11.0 ml/100 g/min (p < 0.001).The findings indicate that the appearance ofCT-negative low flow areas in TIA and stroke patients during the chronic phase is the rule rather than the exception. Flow adaptation to anatomic changes not discernible by CT can be differentiated from clinically relevant flow impairment only by testing the cerebrovascular reserve.

Respiratory function after lesions in medulla oblongata

Abstract Objectives: To evaluate the correlation of lesions of the brain as visualized in cranial magnetic resonance imaging (MRI) and the ability of spontaneous respiration. Methods: In a prospective concept, cranial MRI after traumatic brain injury or spontaneous intracerebral hemorrhage was performed in 250 subjects at an early stage. All MRI findings were correlated with respiratory conditions on the day of examination. Sedation was performed only to facilitate toleration of the artificial ventilation, as and when necessary. Spontaneous respiration could hence be registered clinically. Results: Thirteen subjects (5.2%) had no spontaneous respiration. In these cases, a bilateral lesion of the distal medulla oblongata could be displayed. In four of these cases, no additional injuries of the brainstem were detected. These subjects awoke 2 days after the impact with tetraparesis and apnea. Combined lesions of the medulla oblongata and other brainstem regions were found in nine subjects. All these patients died without awakening. In the absence of a bilateral lesion of the caudal medulla oblongata, spontaneous respiration was always possible. A unilateral lesion of the caudal medulla oblongata was visualized in one patient who had the ability of spontaneous respiration. Conclusions: This work confirms the presence of autonomous respiratory centers within the caudal medulla oblongata that allows sufficient adequate respiration in coma. Respiration ceases in the presence of a bilateral lesion of this area.

Idiopathic Intracranial Hypertension in Monozygotic Female Twins: Intracranial Pressure Dynamics and Treatment Outcome

BACKGROUND Familial cases of idiopathic intracranial hypertension (IIH) are exceedingly rare, and its occurrence in monozygotic twins has not been reported previously. CASE DESCRIPTION We report monozygotic female twins who developed IIH, one at age 25 years and the other at age 28 years. Continuous intracranial pressure (ICP) monitoring confirmed elevated ICP as measured initially by lumbar puncture. In both cases, successful treatment with resolution of papilledema and symptoms relief was achieved after ventriculoperitoneal shunting. CONCLUSIONS This report documents the first case of IIH in monozygotic twins and the associated changes in ICP dynamics. Interestingly, almost equivalent alterations in ICP dynamics were found in the 2 patients.

Time-course of plasma inflammatory mediators in a rat model of brain death

BACKGROUND Brain death (BD) is a donor-associated risk factor that negatively affects transplantation outcome. The inflammation associated with BD appears to have a negative effect on organ quality. Complement activation, apoptosis, and pro-inflammatory cytokine and chemokine expression are significantly increased after BD. To better understand this process, we investigated plasma chemokine and cytokine levels for 8h after BD in a rodent model. METHODS Thirteen healthy adult male Sprague Dawley rats were intubated and mechanically ventilated. After induction of BD, animals were kept hemodynamically stable for 8h. A panel of immune response factors, including cytokines and chemokines, were measured immediately prior to the induction of BD and at 1, 4, and 8h after BD by multiplex analyses in 10 rats. RESULTS In the early phase of BD, we observed an increase in heart rate and a decrease in mean arterial pressure. Only limited fluctuations were noted in the partial pressure of O2, O2 saturation, and HCO3. Monocyte-/macrophage- and lymphocyte-derived mediators (IL-2, IL-4, and IFN-γ) increased steadily during the 8-hour monitoring period. CONCLUSIONS The increase in immune responses, particularly pro-inflammatory responses, after BD is time-dependent. Cytokines and chemokines from donors and recipients require further investigation to determine the optimal time frames for organ transplantation in rodent models and humans.

Shunt Surgery in Idiopathic Intracranial Hypertension Aided by Electromagnetic Navigation.

Background: Idiopathic intracranial hypertension (IIH) is characterized by increased cerebrospinal fluid (CSF) pressure and normal or slit ventricles. Lumboperitoneal shunting had been favored by many investigators for CSF diversion in IIH for decades; however, it has been associated with various side effects. Because of the small ventricular size adequate positioning of a ventricular catheter is challenging. Objectives: Here, we investigated the usefulness of electromagnetic (EM)-guided ventricular catheter placement for ventriculoperitoneal shunting in IIH. Methods: Eighteen patients with IIH were included in this study. The age of patients ranged from 5 to 58 years at the time of surgery (mean age: 31.8 years; median: 29 years). There were 2 children (5 and 11 years old) and 16 adults. Inclusion criteria for the study were an established clinical diagnosis of IIH, lack of improvement with medication, and the presence of small ventricles. In all patients EM-navigated placement of the ventricular catheter was performed using real-time tracking of the catheter tip for exact positioning close to the foramen of Monro. Postoperative CT scans were correlated with intraoperative screen shots to validate the position of the catheter. Results: In all patients EM-navigated ventricular catheter placement was achieved with a single pass. There were no intraoperative or postoperative complications. Postoperative imaging confirmed satisfactory positioning of the ventricular catheter. No proximal shunt failure was observed during the follow-up at a mean of 41.5 months (range: 7-90 months, median: 40.5 months). Conclusions: EM-navigated ventricular catheter placement in shunting for IIH is a safe and straightforward technique. It obviates the need for sharp head fixation, the head of the patient can be moved during surgery, and it may reduce the revision rate during follow-up.

Experimental Rat Model for Brain Death Induction and Kidney Transplantation

Abstract Background: Experimental animal research has been pivotal in developing clinical kidney transplantation (KTx). One donor-associated risk factor with negative affect of transplantation outcome is brain death (BD). Many rat models for BD and KTx have been developed in the last decade, but no surgical guidelines have been developed for these models. Here, we describe a surgical technique for BD induction and the cuff technique for experimental KTx in rats. Methods: After intubation and mechanically ventilation of sixteen healthy adult male Sprague–Dawley rats were induction of BD performed. Animals were kept hemodynamically stable for eight hours. Then, the kidney was prepared and perfused with standard histidine–tryptophan–ketoglutarate solution. After explantation, grafts were immediately implanted in recipients using the cuff technique and reperfused. After 2 h of observation, animals were sacrificed by intravenous administration of potassium chloride. Results: In the early phase of BD, heart rate increased and mean arterial pressure decreased. Partial variations were observed in O2 partial pressure, O2 saturation, and HCO3. During the 2-h observation phase, all transplanted kidneys were sufficiently perfused macroscopically. There was no hyperacute rejection. Conclusions: It is feasible to observe BD for 8 h with maintained circulation in small experimental settings. The cuff technique for KTx is simple, the complication rate is low, and the warm ischemia time is short, therefore, this could be a suitable technique for KTx in the rat model.

Development of Hyperkinesias after Long-term Pallidal Stimulation for Idiopathic Segmental Dystonia

Background Chronic deep brain stimulation (DBS) of the globus pallidus internus (GPi) has become an established treatment for dystonia. While bradykinetic symptoms may occur on chronic stimulation, the appearance of hyperkinetic movements has not been well characterized. Case Report We report on the development of hyperkinesias after more than 10 years of GPi DBS. Discussion Hyperkinesias may evolve upon long-term GPi DBS in dystonia. This might be related to a combined effect consisting of a reduced threshold for effective GPi stimulation for dystonia and spread of current to the globus pallidus externus.