Minimally invasive medial supraorbital, combined subfrontal-interhemispheric approach to the anterior communicating artery complex-a cadaveric study.

INTRODUCTION: In selected cases, microsurgical clipping remains a valuable treatment alternative to endovascular occlusion of anterior communicating artery (AComA) aneurysms. Their clipping is challenging and carries a risk of postsurgical cognitive impairment. We evaluate the microsurgical anatomy of a new, minimally invasive combined interhemispheric-subfrontal approach to the AComA complex via a medial supraorbital craniotomy. METHODS: In this descriptive anatomic study, four alcohol-embedded, silicon-injected human cadaver heads were used. In each of the two cadavers, the AComA complex was approached from either the right or left side. An operating microscope and standard microsurgical instruments were used. RESULTS: After a medial eyebrow incision, a medial supraorbital minicraniotomy was performed. The frontal sinus was opened and cranialized. Following the dural opening, a subfrontal arachnoid dissection was performed to identify the optico-carotid complex. By following the A1 segment, a low-lying AComA complex could be visualized. Shifting the corridor towards the midline enabled an interhemispheric dissection. This dissection resulted in a wide superior-inferior corridor. Higher-lying AComA complexes could also be visualized. The achieved exposure of the AComA complex would allow safe dissection and clipping of low- and high-lying AComA aneurysms, with minimal retraction and preservation of the surrounding anatomical structures, in particular the perforators. CONCLUSIONS: We demonstrate the anatomy of a novel approach for surgical clipping of AComA aneurysms. Our study suggests that this approach provides good exposure without concomitant structural and vascular injury and thus might reduce the risk of procedure-related morbidity.

Effect of ADAMTS-13 on cerebrovascular microthrombosis and neuronal injury after experimental subarachnoid hemorrhage.

BACKGROUND: Microthrombosis and reactive inflammation contribute to neuronal injury after subarachnoid hemorrhage (SAH). ADAMTS-13 cleaves von Willebrand factor multimers, and inhibits thrombus formation and, seemingly, inflammatory reactions. OBJECTIVE: To investigate the effect of ADAMTS-13 in experimental SAH. METHODS: A total of 100 male C57/BL6 mice were randomly assigned to four groups: sham (n = 15), SAH (n = 27), vehicle (n = 25), and ADAMTS-13 (n = 23; 100 µL per 10 g of body weight of 100 µg of ADAMTS-13 per 1 mL of 0.9% NaCl; 20 min after SAH). Neurologic performance was assessed on days 1 and 2 after SAH. Animals were killed on day 2. The amounts of subarachnoid blood, microthrombi, apoptosis and degenerative neurons were compared. The degree of neuronal inflammation and vasospasm was also compared. In five mice each (SAH and ADAMTS-13 groups), bleeding time was assessed 2 h after SAH. RESULTS: Systemic administration of ADAMTS-13 achieved significant amelioration of microthrombosis and improvement in neurologic performance. ADAMTS-13 reduced the amount of apoptotic and degenerative neurons. A tendency for decreased neuronal inflammation was observed. ADAMTS-13 did not show any significant effect on vasospasm. The degree of systemic inflammation was not changed by ADAMTS-13 administration. ADAMTS-13 neither increased the amount of subarachnoid blood nor prolonged the bleeding time. CONCLUSIONS: ADAMTS-13 may reduce neuronal injury after SAH by reducing microthrombosis formation and neuronal inflammation, thereby providing a new option for mitigating the severity of neuronal injury after SAH.

Therapeutic hypothermia reduces middle cerebral artery flow velocity in patients with severe aneurysmal subarachnoid hemorrhage.

BACKGROUND: Transcranial Doppler (TCD) is widely used to detect and follow up cerebral vasospasm after subarachnoid hemorrhage (SAH). Therapeutic hypothermia might influence blood flow velocities assessed by TCD. The aim of the study was to evaluate the effect of hypothermia on Doppler blood flow velocity after SAH. METHODS: In 20 patients treated with hypothermia (33°) due to refractory intracranial hypertension or delayed cerebral ischemia (DCI), mean flow velocity of the middle cerebral artery (MFV(MCA)) was assessed by TCD. Thirteen patients were treated with combined hypothermia and barbiturate coma and seven with hypothermia alone. MFV(MCA) was obtained within 24 h before and after induction of hypothermia as well as before and after rewarming. RESULTS: Hypothermia was induced on average 5 days after SAH (range 1-12) and maintained for 144 h (range 29-270). After hypothermia induction, MFV(MCA) decreased from 113.7 ± 49.0 to 93.8 ± 44.7 cm/s (p = 0.001). The decrease was independent of SAH-related complications and barbiturate coma. MFV(MCA) further decreased by 28.2 cm/s between early and late hypothermia (p < 0.001). This second decrease was observed in patients with DCI (p < 0.001), but not in patients with intracranial hypertension (p = 0.715). Compared to late hypothermia, MFV(MCA) remained unchanged after rewarming (65.6 ± 32.1 vs 70.3 ± 36.8 cm/s; p = 0.219). However, patients treated with hypothermia alone showed an increase in MFV(MCA) after rewarming (p = 0.016). CONCLUSION: Therapeutic hypothermia after SAH decreases Doppler blood flow velocity in both intracranial hypertension and DCI cases. The results can be the effect of hypothermia-related mechanisms or resolving cerebral vasospasm during prolonged hypothermia.

Levetiracetam compared to valproic acid: plasma concentration levels, adverse effects and interactions in aneurysmal subarachnoid hemorrhage.

OBJECTIVE: Both valproic acid and levetiracetam are anti-epileptic drugs, often used either alone or in combination. The present study compares valproate (VPA) with levetiracetam (LEV) as an intravenous (i.v.) anticonvulsant treatment in intensive care patients suffering from aneurysmal subarachnoid hemorrhage (aSAH) with a high risk of seizures. PATIENTS AND METHODS: A prospective, single-center patient registry of 35 intensive care unit (ICU) patients with onset seizure and/or high risk of seizures underwent an anticonvulsive, first-line single treatment regimen either with VPA or LEV. Plasma concentrations (pc), interactions between drugs in the ICU context, adverse effects and seizure occurrences were observed and recorded. RESULTS: A significant decrease in the pc in patients treated with LEV was observed after changing from intravenous (160±51µmol/l) to enteral liquid application (113±58µmol/l), corresponding to a 70.3% bioavailability for enteral liquid applications. The pc in VPA patients decreased significantly, from (491±138µmol/l) to (141±50µmol/l), after adding meropenem to the therapy (p<0.05). Three epileptic seizures occurred during anticonvulsive therapy in the LEV group, and two in the VPA group, including one non-convulsive status epilepticus (NCSE). CONCLUSION: Though this finding needs further verification, the enteral liquid application of levetiracetam seems to be associated with lower bioavailability than the common oral application of levetiracetam. The use of the antibiotic drug meropenem together with valproic acid leads to lower pc levels in patients treated with of valproic acid. For clinical practice, this indicates the need to monitor the levels of valproic acid in combination with meropenem.

Neuromonitoring in intensive care: a new brain tissue probe for combined monitoring of intracranial pressure (ICP) cerebral blood flow (CBF) and oxygenation.

BACKGROUND: the benefits of monitoring cerebral blood flow (CBF) in stroke patients are apparent. New techniques combining near infrared spectroscopy (NIRS) and indocyanine green (ICG) dye dilution to estimate cerebral hemodynamics are available. However, with transcutaneous NIRS and optodes applied over the skin, the signal is contaminated by extracerebral tissues. The objective is to develop a new brain tissue probe for combined monitoring of intracranial pressure (ICP), CBF and cerebral blood volume (CBV). METHODS: conventional intraparenchymal probes for ICP monitoring are supplied with optical fibers. The light is coupled into the brain tissue and collected after absorption and scattering with a light detector. Venous injections of 0.2 mg/kgbw ICG are performed. The mean transit time of ICG (mttICG), CBF and CBV are calculated. RESULTS: with a prototype of the probe in a first patient with subarachnoid hemorrhage 6 pairs of repetitive measurements were performed. Mean values were for mttICG 5.6 ± 0.2 s, CBF 22.3 ± 2.8 ml/100 g/min and CBV 2.1 ± 0.3 ml/100 g. CONCLUSIONS: NIR spectroscopy allows the synchronous determination of multiple parameters with one single device. By measurements in parallel with the NeMo Probe and NIRS optodes placed over the skin, new algorithms can be developed to subtract the extracerebral contamination from the NIRS signal.

Monitoring of the inflammatory response after aneurysmal subarachnoid haemorrhage in the clinical setting: review of literature and report of preliminary clinical experience.

BACKGROUND: Clinical and experimental studies showed a marked inflammatory response in aneurysmal subarachnoid haemorrhage (SAH), and it has been proposed to play a key role in the development of cerebral vasospasm (CVS). Inflammatory response and occurrence of CVS may represent a common pathogenic pathway allowing point of care diagnostics of CVS. Therefore, monitoring of the inflammatory response might be useful in the daily clinical setting of an ICU. The aim of the current report is to give a summary about factors contributing to the complex pathophysiology of inflammatory response in SAH and to discuss possible monitoring modalities. METHODS: Review and analysis of the existing literature and definition of own study protocols. RESULTS: In cerebrospinal fluid, interleukin (IL)-6 has been found to be significantly higher in patients with CVS during the peri-vasospasm period. While systemic inflammatory response syndrome, high C-reactive protein levels and leukocyte counts has been linked with the occurrence of CVS, less has been reported about cytokines levels in the jugular bulb of the internal jugular vein and in the peripheral blood. Preliminary evaluation of own data suggests, that IL-6 values in the peripheral blood and the arterio-jugular differences of IL-6 are increased with the inflammatory response after SAH. CONCLUSION: Monitoring of the inflammatory response, in particular IL-6, might be a useful tool for the daily clinical management of patients with SAH and CVS.

Thalamic cavernous angioma: paraculminar supracerebellar infratentorial transtentorial approach for the safe and complete surgical removal.

BACKGROUND: The thalamic cavernous angioma (CA) represents a neurosurgical challenge because of the critical neurologic functions of the thalamus and its surrounding structures and of their deep location inside the brain. Although the natural history of the thalamic CA remains undefined, several studies suggest the poor outcome of those patients especially if the symptomatic thalamic CA is treated conservatively. We describe the advantage of the paraculminar supracerebellar approach to the lesions in the brainstem. OBJECTIVE: We studied the usefulness and the safety of the paraculminar supracerebellar infratentorial transtentorial approach for the patients with thalamic CA. METHODS: One hundred and ninety two consecutive patients with CA were treated at the Department of Neurosurgery in the Zurich University Hospital between 1993 and 2003. Among these patients, we analyzed six patients (four female, mean age 43) with thalamic CA who underwent surgical removal with the paraculminar supracerebellar transtentorial approach. We retrospectively reviewed their medical charts, the neuroradiological images, and the operative notes/video records. RESULTS: Four patients of the six presented with thalamic hemorrhage. CA existed in the left thalamus in four patients and in the right in two. Preoperative symptoms included sensorimotor disturbance (three cases), double vision (three cases), Parinaud syndrome (one case), and thalamic pain (one case). All patients had the thalamic CA completely removed without any postoperative deterioration. CONCLUSIONS: This study suggests that for the removal of thalamic cavernous angioma the paraculminar supracerebellar infratentorial transtentorial approach provides the spacious surgical field with reduced risks of damaging and sacrificing surrounding vascular and neuronal system. This approach could proffer one of the best and safest surgical routes for the radical removal of thalamic cavernous angioma.

Peripheral large or giant fusiform middle cerebral artery aneurysms: report of our experience and review of literature.

Peripheral large and giant middle cerebral artery (MCA) aneurysms are rare and difficult to treat. We report our and others' experience with different possible modalities used to treat such lesions. Three patients were treated differently at our institution. One harboured a giant fusiform aneurysm on a peripheral branch of the superior trunk of the left MCA, and was treated by extracranial-intracranial (EC-IC) bypass and trapping of the aneurysm. The second patient was harbouring a large fusiform aneurysm on a peripheral branch of the inferior trunk of the right MCA, which was treated by trapping and excision without the need of an EC-IC bypass as assessed pre- and intraoperatively, while the last case was harbouring a giant fusiform aneurysm at the junction of M2-M3 and was treated by EC-IC bypass and end-to-end anastomosis after resection of the aneurysm. The aneurysms proved to be neither mycotic nor dissecting. The patients were clinically intact during their perioperative course without any postoperative complications and required no further treatment. Follow-up angiography demonstrated a functioning EC-IC bypass. Based on the surgical experience in these 3 cases and a review of the reported literature, the authors propose that when considering surgical treatment for such rarely encountered aneurysms, careful pre- and intraoperative evaluation including aneurysm trapping with or without EC-IC bypass when possible should be performed to obtain a satisfactory result without complication.

Seasonal variations in hospital admissions due to aneurysmal subarachnoid haemorrhage in the state of Zurich, Switzerland.

INTRODUCTION: In clinical practice, the occurrence of aneurysmal subarachnoid haemorrhage (SAH) often coincides with a particular season. Our objective was to examine seasonal variations in hospital admissions due to aneurysmal SAH. METHODS: The study population consisted of 489 patients with aneurysmal SAH who were admitted to the Department of Neurosurgery, University Hospital of Zurich, Switzerland, between 1st of January 1996 and 31st of December 2002. Statistical significance of seasonal variation was determined by applying Roger's r test. RESULTS: Statistically significant seasonal variation was only found among patients younger than 60 years, showing a first peak in spring and second lower peak in autumn (Roger's r=6.89, p<0.05). A borderline significance was found in men younger than 60 years (Roger's r=5.96, p=0.051). A trend was observed in patients presenting with Fisher grade 1-2 (Roger's r=5.70, p=0.058). CONCLUSIONS: Previous studies from different countries have shown significant seasonal variations, with the peak period for aneurysmal SAH differing widely. There appears to be some link between aneurysmal SAH and the season of the year or variations in weather conditions. Further investigations are desirable to evaluate which weather or climatic parameters correlate well with SAH.