Martin Lehecka

Microneurosurgical management of anterior communicating artery aneurysms

BACKGROUND Anterior communicating artery complex is the most frequent site of intracranial aneurysms in most reported series. Anterior communicating artery aneurysms are the most complex aneurysms of the anterior circulation due to the angioarchitecture and flow dynamics of the ACoA region, frequent anatomical variations, deep interhemispheric location, and danger of severing the perforators with ensuing neurologic deficits. The authors review the practical microsurgical anatomy, importance of preoperative imaging in surgical planning, and microneurosurgical steps in dissection and clipping of ACoAAs. METHODS This review, and the whole series on intracranial aneurysms, are mainly based on the personal microneurosurgical experience of the senior author (JH) in 2 Finnish centers (Helsinki and Kuopio), which serve, without patient selection, the catchment area in Southern and Eastern Finland. RESULTS These 2 centers have treated more than 10000 patients with aneurysm since 1951. In the Kuopio Cerebral Aneurysm Database of 3005 patients with 4253 aneurysms, 1145 patients (38%) had altogether 1179 ACA aneurysms; of them, 898 patients harbored 921 (78%) ACoAAs. In this series, 715 patients (80%) presented with ruptured ACoAAs with the median diameter of 7 mm. Giant ACoAAs were present in 15 (2%), whereas only 3 (0.3%) were classified as fusiform. CONCLUSIONS Anterior communicating artery aneurysms present frequently with SAH at small size. Furthermore, unruptured ACoAAs may have increased risk of rupture regardless of size, also as an associated aneurysm, and require treatment. The aim in microneurosurgical management of an ACoAA is total occlusion of the aneurysm sac with preservation of flow in all branching and perforating arteries. This demanding task necessitates perfect surgical strategy based on review of the 3D angioarchitecture and abnormalities of the patients ACoA complex with its ACoAA and to orientate accordingly during the microsurgical dissection. The surgical trajectory should provide optimal visualization of the ACoA complex without massive brain retraction. Precise dissection in the 3D anatomy of the ACoA complex and perforators requires not only experience and skill but patience to work the dome and base under repeated protection of temporary clips and pilot clips. This is particularly important with the complex, large, and giant aneurysms.

Saccular intracranial aneurysm disease: distribution of site, size, and age suggests different etiologies for aneurysm formation and rupture in 316 familial and 1454 sporadic eastern Finnish patients.

OBJECTIVEFinnish saccular intracranial aneurysm (sIA) disease associates to 2q33, 8q11, and 9p21 loci and links to 19q13, Xp22, and kallikrein cluster in sIA families. Detailed phenotyping of familial and sporadic sIA disease is required for fine mapping of the Finnish sIA disease. METHODSEastern Finland, which is particularly isolated genetically, is served by Kuopio University Hospitals Department of Neurosurgery. We studied the site and size distribution of unruptured and ruptured sIAs in correlation to age and sex in 316 familial and 1454 sporadic sIA patients on first admission from 1993 to 2007. RESULTSThe familial and sporadic aneurysmic subarachnoid hemorrhage patients had slightly different median ages (46 vs 51 years in men; 50 vs 57 years in women), different proportion of males (50% vs 42%), equal median diameter of ruptured sIAs (7 mm vs 7 mm) with no correlation to age, and equally unruptured sIAs (30% vs 28%). The unruptured sIAs were most frequent at the middle cerebral artery (MCA) bifurcation (44% vs 39%) and the anterior communicating artery (12% vs 13%), in contrast to the ruptured sIAs at the anterior communicating artery (37% vs 29%) and MCA bifurcation (29% vs 29%). The size of unruptured sIAs increased by age in the sporadic group. CONCLUSIONThe MCA bifurcation was most prone to develop unruptured sIAs, suggesting that MCA branching during the embryonic period might be involved. The different site distribution of ruptured and unruptured sIAs suggests different etiologies for sIA formation and rupture. The lack of correlation of size and age at rupture (exposure to risk factors) suggests that the size at rupture is more dependent on hemodynamic stress.

Lateral supraorbital approach applied to olfactory groove meningiomas: experience with 66 consecutive patients.

OBJECTIVEThe lateral supraorbital approach for safely and completely removing olfactory groove meningiomas was assessed. METHODSBetween September 1997 and June 2008, a total of 656 meningiomas were operated on by the senior author (JH) at the Department of Neurosurgery, Helsinki University Central Hospital; 66 were olfactory meningiomas. We retrospectively analyze the clinical data, radiological findings, surgical treatment, histology, and outcome of all the olfactory groove meningioma patients and discuss the operative techniques used. RESULTSSixty-six patients were operated on by the lateral supraorbital approach. The median preoperative Karnofsky Performance Scale score was 80 (range, 40–100). Three patients were redo cases in which the primary operation had been performed elsewhere. Seemingly complete tumor removal was achieved in 60 patients (91%); there was no surgical mortality. Postoperatively, 6 patients (9%) had cerebrospinal fluid leakage, 5 (8%) had new visual deficits, 4 (6%) had wound infections, 4 (6%) had cotton granulomas, and 1 (2%) had a postoperative hematoma. The median Karnofsky score at discharge was 80 (range, 40–100). Six patients had recurrent tumors; 3 underwent reoperations after an average of 21 months (range, 1–41 months); 1 was treated with radiosurgery, and 2 were only followed. During the median follow-up time of 45 months (range, 2–128 months), there were 4 recurrences (6%) diagnosed on average 32 months (range, 17–59 months) after surgery. CONCLUSIONThe lateral supraorbital approach can be used safely for olfactory groove meningiomas of all sizes with no mortality and relatively low morbidity. Surgical results and tumor recurrence with this fast and simple approach are similar to those obtained with more extensive, complex, and time-consuming approaches.

Anatomic risk factors for middle cerebral artery aneurysm rupture: computed tomography angiography study of 1009 consecutive patients.

BACKGROUND In a variety of surgical specialties, simulation-based technologies play an important role in resident training. The Congress of Neurological Surgeons (CNS) established an initiative to enhance neurosurgical training by developing a simulation-based curriculum to complement standard didactic and clinical learning. OBJECTIVE To enhance resident education in the management of traumatic brain injury by the use of simulation-based training. METHODS A course-based neurosurgical simulation curriculum was developed and offered at the 2012 CNS annual meeting. Within this curriculum, a trauma module was developed to teach skills necessary in the management of traumatic brain injury, including the performance of craniotomy for trauma. Didactic and simulator-based instruction were incorporated into the course. Written and practical pre- and posttests, as well as questionnaires, were used to assess the improvement in skill level and to validate the simulator as a teaching tool. RESULTS Fourteen trainees participated in the didactic section of the trauma module. Average performance improved significantly in written scores from pretest (75%) to posttest (87.5%, P < .05). Eight participants completed the trauma craniotomy simulator. Incision planning, burr hole placement (P < .02), and craniotomy size (P < .05) improved significantly. Junior residents (postgraduate years 1-3) demonstrated the most improvement during the course. CONCLUSION The CNS simulation trauma module provides a complementary method for residents to acquire necessary skills in the management of traumatic brain injury. Preliminary data indicate improvement in didactic and hands-on knowledge after training. Additional data are needed to confirm the validity of the simulator.BACKGROUND The middle cerebral artery (MCA) is the most frequent location for unruptured intracranial aneurysms. Controversy remains as to which unruptured MCA aneurysms should be treated prophylactically. OBJECTIVE To identify independent topographical and morphological variables that could predict increased rupture risk of MCA aneurysms. METHODS A retrospective analysis of computed tomography angiography data of 1009 consecutive patients with 1309 MCA aneurysms, referred between 2000 and 2009 to Helsinki University Hospital, was carried out. Morphological and topographical parameters examined for MCA aneurysms comprised aneurysm wall regularity, size, neck width, aspect ratio, bottleneck factor, height-width ratio, location along the MCA, side, distance from the internal carotid artery bifurcation, and dome projection in axial and coronal computed tomography angiography views. Univariate and multivariate logistic regression analyses were performed to determine independent risk factors for rupture. RESULTS Of the 1309 MCA aneurysms, 69% were unruptured and 31% were ruptured. Most unruptured MCA aneurysms were smaller than 7 mm (78%), with a smooth wall (80%) and a height-width ratio of 1 (47%) and were located at the main bifurcation (57%). Ruptured MCA aneurysms, mostly 7 to 14 mm in size (55%), had an irregular wall (78%) and a height-width ratio greater than 1 (72%) and were located at the main bifurcation (77%). Thirty-eight percent of MCA bifurcation aneurysms, 74% of large aneurysms, 64% of aneurysms with an irregular wall, and 49% of aneurysms with a height-width ratio greater than 1 were ruptured. CONCLUSION Location at the main MCA bifurcation, wall irregularity, and less spherical geometry were independently associated with rupture of MCA aneurysms with a correlation with aneurysm size. artery.

Distal anterior cerebral artery aneurysms: treatment and outcome analysis of 501 patients.

OBJECTIVEThis study presents the combined experience of two Finnish neurosurgical centers in the treatment of 501 consecutive patients with distal anterior cerebral artery (DACA) aneurysms. Our aim was to compare treatment outcomes of these lesions with intracranial aneurysms in general and to identify factors predicting the outcome. METHODSWe analyzed the clinical and radiological data of all 501 patients and focused on the 427 patients treated between 1980 and 2005, the era of microsurgery and computed tomographic imaging. No patients were lost to follow-up. We compared treatment and outcome of ruptured DACA aneurysms (n = 277) with all consecutive ruptured aneurysms from the Kuopio Cerebral Aneurysm Database (n = 2243) and used multivariate analysis to identify factors predicting 1-year outcome. RESULTSDACA aneurysms accounted for 6% of all intracranial aneurysms. They were smaller (median, 6 versus 8 mm), more frequently associated with multiple aneurysms (35 versus 18%), and presented more often with intracerebral hematomas (53 versus 26%) than ruptured aneurysms in general. Their microsurgical treatment showed the same complication rates (treatment morbidity, 15%; treatment mortality, 0.4%) as for other ruptured aneurysms. At 1 year after subarachnoid hemorrhage, they had similar favorable outcome (Glasgow Coma Scale score ≥4) as other ruptured aneurysms (74 versus 69%), but their mortality rate was lower (13 versus 24%). Factors predicting unfavorable outcome for ruptured DACA aneurysms were advanced age, Hunt and Hess grade greater than or equal to III, rebleeding before treatment, intracerebral hematoma, intraventricular hemorrhage, and severe preoperative hydrocephalus. CONCLUSIONDespite their specific features, with modern treatment methods, ruptured DACA aneurysms have the same favorable outcome and lower mortality at 1 year as ruptured aneurysms in general.

A new, more accurate classification of middle cerebral artery aneurysms: computed tomography angiographic study of 1,009 consecutive cases with 1,309 middle cerebral artery aneurysms.

BACKGROUND Classification of middle cerebral artery (MCA) aneurysms is sometimes difficult because the identification of the main MCA bifurcation, the key for accurate classification of MCA aneurysms, is inconsistent and somewhat subjective. OBJECTIVE To use the meeting point of the M1 and M2 trunks as an objective, generally accepted, and angiographically evident hallmark for identification of MCA bifurcation and more accurate classification of MCA aneurysms. METHODS We reviewed the computed tomographic angiography data of 1009 consecutive patients with 1309 MCA aneurysms. The M2 trunks were followed proximally until their meeting with the M1 trunk at the main MCA bifurcation. The aneurysms were classified according to their relative location: proximal, at, or distal to the MCA bifurcation. The M1 aneurysms were further subgrouped into M1 early cortical branch aneurysms and M1 lenticulostriate artery aneurysms, extending the classic 3-group classification of MCA aneurysms into a 4-group classification. RESULTS The main MCA bifurcation was the most common location for MCA aneurysms, harboring 829 aneurysms (63%). The 406 M1 aneurysms comprised 242 M1 early cortical branch aneurysms (60%) and 164 M1 lenticulostriate artery aneurysms (40%). We found 106 MCA aneurysms (8%) at the origin of large early frontal branches simulating M2 trunks liable to be misclassified as MCA bifurcation aneurysms. Even though 51% of the 407 ruptured MCA aneurysms were associated with an intracerebral hematoma, this did not affect the classification. CONCLUSION Studying MCA angioarchitecture and applying the 4-group classification of MCA aneurysms is practical and facilitates the accurate classification of MCA aneurysms, helping to improve surgical outcome.

Anatomic features of distal anterior cerebral artery aneurysms: a detailed angiographic analysis of 101 patients.

OBJECTIVEDistal anterior cerebral artery (DACA) aneurysms have special anatomic features such as small size, broad base with originating branches, association with anterior cerebral artery (ACA) anomalies, and multiple aneurysms. Our aim is to evaluate incidences of these findings from pretreatment angiograms to help both microsurgical and endovascular treatment planning. METHODSWe performed detailed angiographic analysis of 101 consecutive patients diagnosed with DACA aneurysms from 1998 to 2007 in the Department of Neurosurgery at the Helsinki University Central Hospital in Helsinki, Finland. All patients underwent either digital subtraction angiography (n = 39) or computed tomographic angiography (n = 62). RESULTSOf the 101 patients, 50 patients (50%) had multiple aneurysms, 7 patients (7%) had multiple DACA aneurysms, and 1 patient (1%) had an associated arteriovenous malformation. The 108 DACA aneurysms were found in seven different locations: frontobasal branches (n = 2); A2 segment (n = 5); A3 segment inferior to genu of corpus callosum (n = 19), anterior to genu of corpus callosum (n = 70), and superior to genu of corpus callosum (n = 1); A4 or A5 segments (n = 7); and distal branches (n = 4). Mean sizes were 7.4 mm (range, 2–35 mm) and 4.2 mm (range, 1–9 mm) for the 67 ruptured and 41 unruptured aneurysms, respectively. A broad base, wider than the parent artery, was seen in 68% of patients, and 94% of patients had a branch origin at the base. The neck-to-dome ratio was 1:1 in 25% of patients. Anomalies of the ACA were seen in 23 patients (23%): azygos ACA in 4 patients (4%), bihemispheric ACA in 15 patients (15%), and triplication of ACA in 4 patients (4%). CONCLUSIONThe special neurovascular features and frequent ACA anomalies, best identified from computed tomographic angiography or rotational digital subtraction angiography, must be taken into account when planning occlusive treatment of DACA aneurysms.

Microneurosurgical management of aneurysms at the A2 segment of anterior cerebral artery (proximal pericallosal artery) and its frontobasal branches

BACKGROUND Aneurysms originating from the A2 segment of ACA and its frontobasal branches are rare, forming less than 1% of all IAs. There are only few reports on management of A2As. In this article, we review the practical anatomy, preoperative planning, and avoidance of complications in the microsurgical dissection and clipping of A2As. METHODS This review, and the whole series on IAs, is mainly based on the personal microneurosurgical experience of the senior author (JH) in two Finnish centers (Helsinki and Kuopio), which serve, without patient selection, the catchment area in Southern and Eastern Finland. RESULTS These two centers have treated more than 10000 patients with IAs since 1951. In the Kuopio Cerebral Aneurysm Database of 3005 patients and 4253 IAs, there were 35 patients carrying 35 A2As, forming 1% of all patients with IAs, 0.8% of all IAs, and 3% of all ACA aneurysms. Twenty-one (60%) patients presented with ruptured A2As with ICH in 11 (52%) and IVH in 7 (33%). Nineteen patients (54%) had multiple aneurysms. CONCLUSIONS A2As are often small, even when ruptured, with relatively wide base, and they are frequently associated with ICHs of IVHs. Our data suggest that A2As rupture at smaller size than IAs in general. The challenge is to select appropriate approach, locate the aneurysm deep inside the interhemispheric fissure, and to clip the neck adequately without obstructing branching arteries at the base. Unruptured A2As also need microneurosurgical clipping even when they are small.

Microsurgical clipping of cerebral aneurysms after the ISAT Study

This landmark study [9] – somewhat Twainian at first glance – sets the stage for future microsurgery in cerebral aneurysms and SAH. The ISAT Study does not nail microsurgery – it will nail microsurgery in low case load neurosurgical centers and in inexperienced hands. In future neurovascular centers, exovascular and endovascular surgeons are forced to support each other by having the full responsibility over the population in a defined geographical area. Exosurgeons will become far more experienced – less in number but not the last Mohicans.

Lateral Supraorbital Approach Applied to Anterior Clinoidal Meningiomas: Experience With 73 Consecutive Patients

BACKGROUND:Anterior clinoidal meningiomas (ACMs) are a subgroup of meningiomas accounting for less than 10% of supratentorial meningiomas. OBJECTIVE:To assess the reliability and safeness of the lateral supraorbital approach (LSO) to remove ACMs. METHODS:Between September 1997 and October 2009, a total of 73 ACM patients were operated on at the Department of Neurosurgery, Helsinki University Central Hospital, by the senior author (J.H.). We retrospectively analyzed the clinical data, radiological findings, surgical treatment, histology, and outcome of patients, and discuss the operative technique. RESULTS:Seventy-three patients were operated on by applying the LSO approach. Apparently complete removal was achieved in 57 patients (78%). Anterior clinoidectomy was performed in 21 cases. Preexisting visual deficit improved in 11 of 39 patients and worsened in 4; 3 had de novo visual deficit. At 3 months after discharge, 60 (82%) patients had a good recovery, 9 (12%) patients were moderately disabled, 1 presented with severe disability, and 3 (4%) patients died of surgery-related causes. Sixteen (22%) patients had residual tumors, 6 of which required reoperation. During the median follow-up of 36 months (range, 3-146), tumor recurred in 3 patients: 2 were followed-up and 1 was reoperated on. CONCLUSION:ACMs can be removed via the LSO approach with relatively low morbidity and mortality. Anterior clinoidectomy is required only in selected cases, and we prefer the intradural approach during the LSO approach. High-power coagulation should be avoided in proximity of the optic nerve.