Niklaus Krayenbühl

Results of microsurgical clipping of 50 high complexity basilar apex aneurysms. Commentary

OBJECTIVEComplex basilar aneurysms (large size, wide base, low bifurcation, and dysmorphic posteriorly projecting domes) frequently fail endovascular treatment. We report our experience using the pretemporal transzygomatic transcavernous approach with 50 complex basilar aneurysms. METHODSUsing the pretemporal transcavernous route, opening the occulomotor trigone, and removing the anterior clinoid and the posterior clinoid when necessary, a wide exposure of the interpeduncular fossa is achieved. Temporary clips are applied to a perforator-free zone of the basilar trunk, proximal to the superior cerebellar artery. Complexity criteria in the 50 aneurysms included large or giant size in 27 patients, wide dysmorphic base in 18 patients, low bifurcation in 21 patients, posteriorly projecting dome in 11 patients, and dolichoectasia of the apex in three patients. RESULTSTwenty-five patients presented with subarachnoid hemorrhage. There were 14 men and 36 women between the ages of 32 and 76 years (mean, 52.2 yr). Forty-nine aneurysms (98%) were successfully clipped. There was no procedure-related mortality. Two patients died (one from delayed bowel ischemia and one from a vasospasm-related complication). There were three ischemia-related events, two of which were procedure-related (medial thalamic lacunar infarct, superior cerebellar distribution ischemia) and one which was a third distal middle cerebral cardiac embolus after stopping Coumadin (DuPont Pharmaceuticals, Wilmington, DE) for atrial fibrillation. Transient partial or complete occulomotor palsies occurred in all patients with full recovery as the rule, except in one patient. At discharge, Glascow Outcome Scale scores were 4 or 5 in 88% of the patients. At the 6-month follow-up examination, Rankin Outcome Scale scores were 0 to 2 in 92% of the patients. CONCLUSIONOur experience reintroduces microsurgery as a safe and more durable treatment option for the management of complex basilar apex aneurysms that tend to have a higher rate of failure with endovascular therapy.

The selective amygdalohippocampectomy for intractable temporal limbic seizures.

OBJECT The proximal (anterior) transsylvian approach through a pterional craniotomy was developed by the senior author (M.G.Y.) in 1967 for the microsurgical treatment of saccular aneurysms of the circle of Willis, frontoorbital and temporobasal arteriovenous malformations, cavernomas, and extrinsic and intrinsic tumors. The acquired positive surgical experiences on this large series enabled the senior author, in 1973, to apply this approach for the selective amygdalohippocampectomy in patients with intractable mesial temporal lobe epilepsy. METHODS The proximal (anterior) transsylvian-transamygdala approach to the mesial temporal structures permits the selective two-thirds resection of the amygdala and hippocampus-parahippocampus in an anteroinferior to posteroinferior exploration axis along the base of the semicircular temporal horn. This strategy ensures preservation of the overlying neopallial temporal convolutions such as the T1, T2, T3, and T4 gyri as well as the related subcortical connective fiber systems and other essential components of the temporal white matter. The application of rigid brain self-retaining retractor systems was strictly avoided during the entire procedure. Computer-assisted navigation was never used. On routine postoperative CT scanning and MR imaging studies, infarction was not observed in any patient. The availability of tractography technology has proven that the connective fiber system around the resected mesial temporal area remains intact. RESULTS The surgical outcome and results on neoplastic and vascular lesions of the mesiobasal temporal region have been presented in Volumes II, IIIB, and IVB of Microneurosurgery. The surgical outcomes and results in 102 patients with mesial temporal seizures who underwent surgery performed by the senior author in Zürich have been previously published. In this paper, 73 patients who underwent surgery between 1994 and September 2006 in Little Rock, Arkansas, are presented, and 13 other patients are excluded who underwent surgery after September 2006. Altogether, among 188 patients who underwent surgery, there was no surgical mortality or morbidity, and no neurological deficits, new neurocognitive dysfunction, or impairments of the preoperative incapacities. CONCLUSIONS The surgical outcome in terms of seizures was rewarding in the majority of patients, particularly in those who exhibited the following irregularities on preoperative investigations: regular local dysfunctions on electroencephalography, dysmorphic changes in the mesiobasal temporal parenchyma on MR imaging studies, and hypometabolism in the anterior third of the temporal lobe on PET studies.

Human Intracranial High Frequency Oscillations (HFOs) Detected by Automatic Time-Frequency Analysis

Objectives High frequency oscillations (HFOs) have been proposed as a new biomarker for epileptogenic tissue. The exact characteristics of clinically relevant HFOs and their detection are still to be defined. Methods We propose a new method for HFO detection, which we have applied to six patient iEEGs. In a first stage, events of interest (EoIs) in the iEEG were defined by thresholds of energy and duration. To recognize HFOs among the EoIs, in a second stage the iEEG was Stockwell-transformed into the time-frequency domain, and the instantaneous power spectrum was parameterized. The parameters were optimized for HFO detection in patient 1 and tested in patients 2–5. Channels were ranked by HFO rate and those with rate above half maximum constituted the HFO area. The seizure onset zone (SOZ) served as gold standard. Results The detector distinguished HFOs from artifacts and other EEG activity such as interictal epileptiform spikes. Computation took few minutes. We found HFOs with relevant power at frequencies also below the 80–500 Hz band, which is conventionally associated with HFOs. The HFO area overlapped with the SOZ with good specificity > 90% for five patients and one patient was re-operated. The performance of the detector was compared to two well-known detectors. Conclusions Compared to methods detecting energy changes in filtered signals, our second stage - analysis in the time-frequency domain - discards spurious detections caused by artifacts or sharp epileptic activity and improves the detection of HFOs. The fast computation and reasonable accuracy hold promise for the diagnostic value of the detector.

CHRONIC SUBDURAL HEMATOMAS TREATED BY BURR HOLE TREPANATION AND A SUBPERIOSTAL DRAINAGE SYSTEM

OBJECTIVEMost symptomatic chronic subdural hematomas are treated by subdural drainage. However, a subperiostal (i.e., extracranial) passive closed-drainage system in combination with double burr hole trepanation is used at our institution. Therefore, we wanted to analyze our results and compare them with the alternate treatment strategies reported in the current literature. METHODSIn a retrospective single-center study, we analyzed the data of all patients undergoing double burr hole trepanation with a subperiostal passive closed-drainage system. Data analysis included general patient data, complications, postoperative seizure rate, and outcome. RESULTSOne hundred forty-seven patients underwent surgery for 183 symptomatic chronic subdural hematomas. The perioperative mortality rate was 3.4%. Hematoma persistence or recurrence occurred in 13.1% of the cases. The postoperative seizure rate was 6.6%, and the infection rate was 1.6%, including 3 cases of superficial wound infection and 1 case with deep infection. The reintervention rate was 9.3%, including trepanation in 8.2% of the patients and craniotomy in 1.1%. The overall complication rate was 10.9%. CONCLUSIONDouble burr hole trepanation combined with a subperiostal passive closed-drainage system is a technically easy, highly effective, safe, and cost-efficient treatment strategy for symptomatic chronic subdural hematomas. The absence of a drain in direct contact with the hematoma capsule may moderate the risk of postoperative seizure and limit the secondary spread of infection to intracranial compartments.

The relationship of the fronto-temporal branches of the facial nerve to the fascias of the temporal region: a literature review applied to practical anatomical dissection

The understanding of the course of the facial nerve and its relationship to the different connective tissue layers in the temporal area is paramount to preserving this nerve during surgery. But the use of different nomenclatures for anatomical structures such as for the different fascial layers or fat pads in the temporal region as well as the difference in description of the course of the fronto-temporal branches of the facial nerve in relationship to the fascial layers can lead to confusion. Therefore we have reviewed the literature about this topic and tried to apply the information to practical anatomical dissection.

Symptomatic and Silent Ischemia Associated With Microsurgical Clipping of Intracranial Aneurysms Evaluation With Diffusion-Weighted MRI

Background and Purpose— Silent ischemic events are known to occur during diagnostic and interventional endovascular procedures between 10% and 69% of the time. The occurrence of silent and symptomatic ischemic events in the surgically treated population is not known, although atherosclerotic changes of intracranial vessels or within the aneurysms wall or neck area are seen often during surgery. Methods— Patients with unruptured and ruptured intracranial aneurysms treated by microsurgical clipping were prospectively evaluated with MRI using diffusion-weighted imaging sequences before and within 24 hours after surgery. Patients were evaluated clinically before and after surgery. During surgery, the overall and maximal time of temporary occlusion as well as the total number of temporary and finally applied clips was noted. Diffusion-weighted images were analyzed with determination and characterization of diffusion-weighted imaging abnormalities. Results— Thirty-six patients with 51 aneurysms were included. One symptomatic and 5 silent ischemic lesions were found in 5 patients. This represents a risk of silent ischemia of 9.8% per treated aneurysm and a risk of symptomatic stroke of 2%. The most significant risk factor in increasing order was: age (P<0.05), presence of thrombus (P<0.05), number of final clips applied (P<0.05), number of temporary clips used (P<0.01), total time of temporary clip occlusion (P<0.001), and maximal time of temporary occlusion (P<0.001). Conclusions— The risk of silent and symptomatic ischemic events during microsurgical clipping of intracranial aneurysms seems to be low. Microsurgical clipping is safe and should continue to be strongly considered as a treatment option.

Spontaneous otogenic intracerebral pneumocephalus: case report and review of the literature

Pneumocephalus is commonly associated with head and facial trauma, ear infection or surgical interventions. We describe the rare case of a spontaneous pneumocephalus arising from lateral mastoid air cells. A 48-year-old man presented with a 10-day history of sudden, repetitive, ‘hammering-like’ acoustic sensations in his left ear that were followed by word-finding difficulties and loss of vision in the right visual field. Imaging revealed a large, left temporal pneumatocele associated with a small acute intracerebral hemorrhage. Left temporal and subtemporal craniotomy and decompression were performed. Further exploration confirmed a dural and osseous defect in the anterolateral surface of the mastoid that was consecutively closed watertight. Although extremely rare, a spontaneous pneumocephalus with mastoidal origin should be considered as a possible diagnosis in patients with suggestive acoustic phenomena and other non-specific neurological symptoms.

Cerebral vasospasm: results of a structured multimodal treatment

Symptomatic cerebral vasospasm (CVS) with delayed ischemic neurologic deficits affects about one third of the patients after aneurysmal subarachnoid hemorrhage (SAH). In spite of the lack of definite evidence of large clinical trials, the devastating outcome of the natural history of symptomatic CVS demands an aggressive CVS treatment in a practically oriented, structured multimodal treatment regimen. With our treatment protocol good functional outcome could be reached in 66% of the patients with symptomatic CVS. This policy requires close and fast multidisciplinary collaboration between neurosurgeons, neuroradiologists, competent in endovascular interventions, and specialists for neurointensive care. We report on our experience with 79 cases with symptomatic CVS and delayed ischemic neurologic deficit (DIND) after aneurysmal SAH. The different treatment options with CVS are reviewed and practical guidelines for a step by step treatment are given.

Hydrocephalus in 389 patients with aneurysm-associated subarachnoid hemorrhage

Subarachnoid hemorrhage (SAH) often leads to hydrocephalus, which is commonly treated by placement of a ventriculoperitoneal (VP) shunt. There is controversy over which factors affect the need for such treatment. In this study, data were prospectively collected from 389 consecutive patients who presented with an aneurysm-associated SAH at a single center. External ventricular drainage placement was performed as part of the treatment for acute hydrocephalus, and VP shunts were placed in patients with chronic hydrocephalus. The data were retrospectively analyzed using two-sample t-tests, Fishers exact test and logistic regression analysis. Overall, shunt dependency occurred in 91 of the 389 patients (23.4%). Using logistic regression analysis, two factors were found to be significantly associated with VP shunt placement: an initial Glasgow Coma Scale (GCS) score of 8-14 (8-14 versus 3-7, p = 0.016; 15 versus 3-7, p = 0.55); and aneurysm coiling (p = 0.017). Patients with an initial GCS score of 8-14 after aneurysm-associated SAH had a 2.5-fold higher risk of receiving a VP shunt than those with a GCS score of 3-7. Those with a GCS of 15 had a 50% lower risk of becoming shunt dependent than did the subgroup with a GCS score of 8-14. To clarify and strengthen these observations, prospective, randomized trials are needed.

Subdural Drainage versus Subperiosteal Drainage in Burr-Hole Trepanation for Symptomatic Chronic Subdural Hematomas

BACKGROUND Symptomatic chronic subdural hematoma (scSDH) is one of the most frequent diseases in neurosurgical practice, and its incidence is increasing. However, treatment modalities are still controversial. OBJECT The aim of this retrospective single-center study is to compare for the first time two surgical methods in the treatment of subdural hematoma that have been proven to be efficient in previous studies in a direct comparison. METHODS We analyzed the data of 143 scSDHs in 113 patients undergoing surgery for subdural hematoma with placement of subperiosteal or subdural drainage after double burr-hole trepanation for hematoma evacuation. RESULTS Overall, there were no statistically significant differences regarding general patient characteristics, preoperative and postoperative symptoms, postoperative hematoma remnant, rates of recurrences, mortality, complications, and outcome at discharge and at 3-month follow up between the groups. There was a close to significant tendency of lower mortality after placement of subperiosteal drainage system and a tendency towards lower rate of recurrent hematoma after placement of subdural drainage system. CONCLUSIONS Our study shows for the first time a direct comparison of two mainly used surgical techniques in the treatment of scSDH. Both methods proved to be highly effective, and general patient data, complications, outcome and mortality of both groups are equal or superior compared with previously published series. Because there is a clear tendency to less mortality and fewer serious complications, treatment with double burr-hole trepanation, irrigation, and placement of subperiosteal drainage is our treatment of choice in patients with predictable high risk of complications.