Leon Lai

Predictors of in-hospital shunt-dependent hydrocephalus following rupture of cerebral aneurysms

The development of shunt-dependent hydrocephalus is a well-recognised complication after aneurysmal subarachnoid haemorrhage, and negatively impacts on outcomes among survivors. This study aimed to identify early predictors of shunt dependency in a large administrative dataset of aneurysmal subarachnoid haemorrhage patients. We reviewed the National Hospital Morbidity Database in Australia for the years 1998 to 2008 and investigated the incidence of ventricular shunt placement following aneurysmal subarachnoid haemorrhage admissions. Putative risk factors were evaluated with univariate and multivariate logistic regression analysis to identify independent predictors of outcome. The following variables were considered: poor admission neurological grade; aneurysm location; intracerebral haemorrhage; intraventricular haemorrhage; acute hydrocephalus requiring the insertion of an external ventricular drain; surgical clipping; endovascular coiling; meningitis; and prolonged period of external ventricular drainage. A total of 10807 patients hospitalised for aneurysmal subarachnoid haemorrhage were identified. Among them, 701 (6.5%) required a permanent cerebrospinal fluid diversion procedure during the same admission as the aneurysmal subarachnoid haemorrhage. On multivariate analysis, poor admission neurological grade, acute hydrocephalus, the presence of intraventricular haemorrhage, ruptured vertebral artery aneurysm, surgical clipping, endovascular coiling, meningitis, and a prolonged period of external ventricular drainage were significant predictors of shunt dependency. A patient with a ruptured middle cerebral artery aneurysm was unlikely to develop shunt dependency (odds ratio 0.58; 95% confidence interval 0.46-0.73; p < 0.001).

Outcomes for unruptured ophthalmic segment aneurysm surgery

Ophthalmic segment aneurysms present unique technical challenges because of their proximity to the optic nerve and the anterior clinoid process. The current study was performed to examine whether surgery for unruptured ophthalmic segment aneurysms is an effective treatment modality with acceptable complication rates. A consecutive case series (prospectively collected data) was retrospective reviewed for the period between April 1992 and August 2012. Clinical results, operative complications, angiographic outcomes and prognostic factors associated with surgery are presented. Of the 169 patients with 182 unruptured ophthalmic segment aneurysms that were surgically repaired, 11 (6.4%) experienced new permanent neurological deficits, including six instances of complete visual loss. There was one postoperative death (0.6%) related to a middle cerebral artery infarction. Transient morbidity occurred in 18 patients (10.4%), including cerebrospinal fluid rhinorhea (10 patients), oculomotor nerve palsy (four patients) and transient dysphasia (four patients). A total of 142 aneurysms (78.0%) had documented postoperative angiography. Surgical treatment resulted in 135 (95.1%) complete obliterations and seven (4.9%) neck remnants. Retreatment was performed in three patients (1.7%). Logistic regression analysis of risk factors revealed that age (p < 0.02), aneurysm size (p < 0.01) and the use of temporary clipping (p < 0.01) were significant negative predictors of outcome. The risk associated with surgical repairs for unruptured ophthalmic segment aneurysms is no greater than aneurysms in other locations (6.4% morbidity; 0.6% mortality) and no more hazardous than outcomes achieved by alternative therapies. The robustness of aneurysm repair achieved by open microsurgery is an important consideration.

The impact of changing intracranial aneurysm practice on the education of cerebrovascular neurosurgeons

Endovascular repair of intracranial aneurysms has transformed the practice of cerebrovascular surgery. We reviewed the National Hospital Morbidity Database in Australia for the years 2000 to 2008 and investigated the changing trends of aneurysm practice. During this period 7,503 craniotomies for aneurysm repair and 7,863 endovascular coiling procedures were performed. The number of aneurysm procedures performed surgically reduced from 9 cases per neurosurgeon per year to 4.2 cases, a reduction of 53.3%. The number of endovascular treatments increased 2.1 fold, from 3.6 aneurysms per neurosurgeon in 2000 to 7.5 in 2008. The implications of reduced numbers of surgically treated aneurysms were considered for the education of cerebrovascular neurosurgeons in Australia.

Incidence of subarachnoid haemorrhage: An Australian national hospital morbidity database analysis

Incidences of subarachnoid haemorrhage (SAH) in Australia have been reported in regional studies with variable rates. We investigated the national SAH rate and evaluated the trend over the 10 years from 1998 to 2008. The crude SAH incidence, not related to trauma or arteriovenous malformation, was estimated at 10.3 cases per 100,000 person-years (95% confidence interval [CI]: 10.2-10.4). Females have a higher incidence of SAH (12.5 cases per 100,000; 95% CI: 12.3-12.8) compared to males (8.0 cases per 100,000; 95% CI: 7.8-8.3), with age-adjusted incidence increases with increasing age for both sexes. Less than 10% of SAH occurred in the first three decades of life. The peak age group for patients to experience SAH was between 45 years and 64 years, accounting for almost 45% of the overall annual SAH admissions. Aneurysms located in the anterior circulation were a more common source of rupture compared to those located in the posterior circulation (rate ratio 3.9; 95% CI: 3.6-4.2). Contrary to contemporary observations in the literature, we did not observe a decline in the incidence of SAH during this specified study period.

Smoking increases the risk of de novo intracranial aneurysms.

OBJECTIVE Case series have identified that de novo intracranial aneurysms occur. However, the risk for this occurrence has not been established. We examined the risk for the de novo intracranial aneurysm detection in a consecutive surgical case series. METHODS A prospectively collected surgical database of intracranial aneurysms was retrospectively examined. Patients were analyzed if they were followed for more than 6 months postoperatively with angiography. Kaplan-Meier curve analysis of de novo aneurysms detection included the comparison of smoking vs. never smoked; those with and without a family history; single vs. multiple aneurysms at initial presentation; and original presentation with rupture vs. nonrupture. RESULTS Of the 1366 surgically treated patients (1942 aneurysms), 472 patients (702 aneurysms) were followed with angiography for more than 6 months (average, 54 months). Thirty-three patients (6.99%) were detected to have de novo aneurysms. Multivariate analysis found a smoking history significantly increases the likelihood of de novo aneurysm detection. Kaplan-Meier analysis found the 5- and 10-year de novo aneurysm detection rate to be 4.21% (95% confidence interval [CI] 3.86-12.8) and 15% (95% CI 10-16), respectively. A smoking history increases the 5- and 10-year detection rate to 5.81% and 17% (hazard ratio 2.58; 95% CI 1.13-5.90) respectively. No increased risk was present for an initial presentation that included multiple aneurysms, a family history, or rupture. CONCLUSION There is a 10-year de novo aneurysm detection rate of between 10% and 16% after surgery. Smoking increases the risk of de novo aneurysm detection. Consideration needs to be given to surveillance angiography after aneurysm treatment.

The risk of meningitis following expanded endoscopic endonasal skull base surgery: A systematic review

Objective To examine the risk of postoperative meningitis following expanded endoscopic endonasal skull base (EESB) surgery. Setting A systematic analysis of publications identified through searches of the electronic databases from Embase (1980-July 17, 2012), Medline (1950-July 17, 2012), and references of review articles. Main Outcome Measures Incidence of meningitis following EESB surgery. Results A total of 2,444 manuscripts were selected initially, and full-text analysis produced 67 studies with extractable data. Fifty-two contained data regarding the frequency of postoperative meningitis. The overall risk of postoperative meningitis following EESB surgery was 1.8% (36 of 2,005). For those reporting a cerebrospinal fluid (CSF) leak, meningitis occurred in 13.0% (35 of 269). For those not reporting a CSF leak, meningitis occurred in 0.1% (1 of 1,736). The odds ratio for the development of meningitis in the presence of a postoperative CSF leak was 91.99 (95% confidence interval, 11.72-721.88; p < 0.01). There was no difference in reported incidence of meningitis or CSF leak between anterior and posterior cranial fossa surgery. There was one reported case of meningitis-related mortality following EESB surgery. Conclusion The evidence in skull base surgery is limited. This study demonstrates a low incidence of meningitis (1.8%) following EESB procedures. The incidence of meningitis from EESB surgery without an associated CSF leak is uncommon.

Cadaveric study of the endoscopic endonasal transtubercular approach to the anterior communicating artery complex

The endoscopic transnasal approach to the anterior communicating artery (ACoA) complex is not widely performed. This cadaveric study investigated the surgical relevance of the anterior endoscopic approach to the treatment of ACoA aneurysms. Bi-nasal endoscopic transtubercular surgery was carried out on fresh adult cadavers. Primary outcomes measures incorporated dimensions of the endonasal corridor (operative field depth, lateral limits, size of the transplanum craniotomy and dural opening); vascular exposure (proximal and distal anterior cerebral arteries [ACA], ACoA, clinoidal internal carotid artery [ICA] segment); and operative manoeuvrability defined by clip placements (ipsilateral and contralateral). Eight cadaver heads were used (mean age 84±7years, range 76-94 years, 75% female). Mean operative depth was 97±4mm. The lateral corridors were limited proximally by the alar rim openings (31±2mm), and distally by the optic nerves (22±6mm). The endonasal craniotomy dimensions were 21±5mm anteroposteriorly, and 22±4mm laterally. Vascular exposure was achieved in 100% of subjects for the ACoA segment and the ACA segments proximal to the ACoA (A1). The ACA segments distal to the ACoA (A2) were accessible only in 40% of subjects. Endonasal clip placement across the ACoA segment, clinoidal ICA, A1 and A2 were 100%, 90%, 90%, and 30%, respectively. The ventral endoscopic endonasal approach to the ACoA complex provides excellent vascular visualisation without brain retraction or gyrus rectus resection. However, the limitation in access to the A2 for temporary clip placement may prove to be a significant limitation of this approach.

A systematic review of published evidence on expanded endoscopic endonasal skull base surgery and the risk of postoperative seizure

Although postoperative seizure is an acknowledged risk following transcranial surgery, the incidence of seizure after removal of intradural pathology via an expanded endoscopic endonasal approach is not well defined. The current study was performed to systematically review the risk of seizure in patients undergoing endoscopic endonasal skull base (EESB) surgery. Embase (1980 to 9 March 2012) and Medline (1950 to 9 March 2012) were searched using a search strategy designed to include any studies that report the perioperative outcomes following EESB surgery. Outcomes of patients undergoing a simple closure of cerebrospinal fluid fistulae or encephaloceles and transellar approaches for pituitary or intrasellar lesions were excluded because this review is focused on large skull base defects. A title search selected those articles relevant to clinical series on expanded endoscopic approaches. A subsequent search of abstracts selected for manuscripts of any report that documented the presence or absence of postoperative seizure. A total of 2234 manuscripts were selected initially and full text analysis produced 67 studies with extractable data regarding the perioperative outcomes for EESB surgery. Of these manuscripts, seven reported the incidence of seizure following EESB procedures. Two of these studies were excluded due to duplication of authorship and institutional data. The overall risk of postoperative seizure following EESB surgery was estimated at 1.1% (six of 530). Subgroup analyses of data revealed that the risk of seizure following an endoscopic endonasal to the anterior cranial base was 2.3% (one patient of 43). For a posterior cranial base approach, the risk of seizure was indeterminate due to deficiency of reporting in the current literature. We concluded that the risk of seizure following an EESB procedure appears to be low (1%). However, the lack of reporting on the incidence of seizures or the use of antiepileptic prophylaxis following EESB procedure is a key limitation. Future EESB studies will need to include seizure as an outcome to accurately define this risk.

Endoscopic Endonasal Transplanum Approach to the Paraclinoid Internal Carotid Artery

Objective To investigate the relevance of an endoscopic transnasal approach to the surgical treatment of paraophthalmic aneurysms. Setting Binasal endoscopic transplanum surgery was performed. Participants Seven cadaver heads were studied. Main Outcome Measures (1) Dimensions of the endonasal corridor, including the operative field depth, lateral limits, and the transplanum craniotomy. (2) The degree of vascular exposure. (3) Surgical maneuverability and access for clip placements. Results The mean operative depth was 90 ± 4 mm. The lateral corridors were limited proximally by the alar rim openings (29 ± 4 mm) and distally by the distance between the opticocarotid recesses (19 ± 2 mm). The mean posteroanterior distance and width of the transplanum craniotomy were 19 ± 2 mm and 17 ± 3 mm, respectively. Vascular exposure was achieved in 100% of cases for the clinoidal internal carotid artery (ICA), ophthalmic artery, superior hypophyseal artery, and the proximal ophthalmic ICA. Surgical access and clip placement was achieved in 97.6% of cases for vessels located anterior to the pituitary stalk (odds ratio [OR] 73.8; 95% confidence interval [CI] 7.66 to 710.8; p = 0.00). Conclusion The endoscopic transnasal approach provides excellent visualization of the paraclinoid region vasculature and offers potential surgical alternative for paraclinoid aneurysms.

Outcomes for a case series of unruptured anterior communicating artery aneurysm surgery

Surgical outcomes following repair of unruptured anterior communicating artery (AcomA) aneurysms have not been adequately addressed in the literature. We present our operative experiences in a consecutive series of 103 patients with 115 unruptured AcomA aneurysms. Clinical results, operative complications, angiographic outcomes and prognostic factors associated with surgery are presented. Of the 115 aneurysm repairs attempted, 114 were treated by clipping or excision and suture. One aneurysm, less than 2mm, was wrapped. Six patients (5.8%; 95% confidence interval [CI], 2.5-12.4) experienced a new permanent neurological deficit. There was no postoperative mortality. Transient morbidity occurred in 11 patients (10.7%; 95% CI, 5.9-18.3), including transient anosmia (four patients), acute postoperative confusion and memory disturbances (four patients), extradural haematoma requiring surgery (two patients) and cerebrospinal fluid rhinorrhea (one patient). Of the 84 aneurysms (73.0%) that had documented postoperative angiography, 82 (97.6%) had complete obliteration of the aneurysm and two (2.4%) had neck remnants (mean angiographic follow-up 28.0 months; range, 1.6-146.4 months). Retreatment was performed in one patient (1.0%). Logistic regression analysis of risk factors revealed that aneurysm size (p<0.01) was a significant predictor of outcome. There was no incidence of subarachnoid haemorrhage in the 272 person years of follow-up. In the current study, surgical treatment of unruptured AcomA aneurysms resulted in 5.8% morbidity and no mortality. The robustness of aneurysm repair achieved by open microsurgery is an important consideration when considering the option between endovascular and microsurgical treatment for unruptured AcomA aneurysms.