Image-guided microneurosurgical management of small arteriovenous malformation: role of neuronavigation and intraoperative Doppler sonography.

INTRODUCTION: The goal of this study was to evaluate the efficacy and reliability of neuronavigation and intraoperative microvascular Doppler sonography (MDS) for identifying afferent (feeding) and efferent (draining) vessels as well as for controlling the totality of the surgical resection of arteriovenous malformations (AVMs). METHODS: Between June 2000 and November 2005, twenty-five patients with small arteriovenous malformations (grades I-III) underwent microsurgical removal at our institution. A passive-marker-based neuronavigation system (Brain Lab, Munich, Germany), and an intraoperative MDS (Multi Dop X system, DWL, Germany) were used in this surgery. Blood flow velocities (BFV) in afferent and efferent vessels were recorded before and after removal of AVM. The preoperative neurological status and postoperative outcome were recorded. Patient follow-up monitoring ranged from 4 months to 3 years (mean: 16 months). RESULTS: The calculated registration accuracy of the neuronavigation computer ranged between 0.2-1.7 mm (mean: 1.1 mm). Before AVM removal the mean BFV of afferent vessels was 56.5+/-13.4 (28-98 cm/s) and the PI varied by 0.40+/-0.11 (0.25-0.66), after AVM removal these values reduced to 4.8+/-0.8 cm/s and 0.26+/-0.05, respectively. Similarly, before AVM removal, the mean BFV of efferent vessels was 13.5+/-4.5 (4-20 cm/s) and PI was 0.4+/-0.2 (0.34-0.56), after AVM removal both BFV and PI were not recorded. Complete removal of the AVMs was accomplished in 24 (96%) out of 25 patients which was confirmed with postoperative digital subtraction angiography (DSA). While there was no mortality, three patients (12%) had a worsening in their neurological status after surgery. CONCLUSION: Image-guided microneurosurgery with intraoperative MDS is a safe, effective, and reliable method for identifying the afferent and efferent vessels and for confirming the complete resection of AVMs. These benefits of image-guided microsurgery were most apparent for small, deep-seated AVMs that were not visible on the surface of the brain. In addition these techniques reduce the operative time and blood loss during AVM resection.

Intraoperative microvascular Doppler sonography in aneurysm surgery.

OBJECTIVE: The goal of this study was to evaluate the efficacy and reliability of intraoperative microvascular Doppler sonography (MDS) for the assessment of cerebral haemodynamics in aneurysm surgery. METHODS: For 40 patients (21 men, 19 women, mean age 54.0 years, range 23-73 years) who underwent surgery for the treatment of 48 intracranial aneurysms, microvascular Doppler sonography with a 20-MHz microprobe was used before and after clip application, to confirm the complete obliteration of the aneurysm. Postoperative angiography was performed to assess the complete occlusion of the aneurysm and the patency of adjacent vessels. The findings of MDS were analysed and compared with the postoperative angiography. RESULTS: A 1-mm diameter microprobe was able to insonate all vessels of the circle of Willis and their major branches and perforating arteries were reliably insonated. The aneurysm clip was repositioned on the basis of the MDS findings in 12 out of 48 patients (25%). For 9 aneurysms (18.7%) MDS exposed a relevant stenosis of an adjacent vessel induced by clip positioning that had escaped detection by visual inspection. Clip repositioning resulted in complete occlusion of the aneurysms in 7 of 9 cases (14.5%). In two cases, additional wrapping became necessary as it was not possible to achieve complete clipping. The mean duration of MDS investigations was 5.3 minutes. There were no complications of intraoperative MDS probe use. CONCLUSION: Intraoperative MDS should be used routinely in cerebral aneurysm surgery, especially for large, complicated and giant aneurysms. Intraoperative MDS is a feasible, safe, and very reliable technique in aneurysm surgery. This technique is a valuable tool, in many instances, in place of intraoperative angiography for the surgical treatment of aneurysms.

Surgical treatment of distal anterior cerebral artery aneurysms with horizontal head position.

OBJECTIVE: In the surgery for a distal anterior cerebral aneurysm which is applied with a vertical head position, the dome of the aneurysm makes it difficult the expose the neck and the proximal artery. This study was performed to evaluate the applicability of the alternative contralateral interhemispheric approach with a horizontal head position for clipping these aneurysms. METHOD: The head of the patient was placed in the horizontal position such that the aneurysm side remained at the top and then tilted 45 degrees superiorly. On the contralateral side, the craniotomy, interhemispheric dissection and clipping were performed in 12 patients with 13 aneurysms. RESULTS: All aneurysms were clipped successfully. Problems in the standard supine position such as the obstruction of the access to the aneurysm neck and the proximal artery by the dome were not encountered. Vasospasm developed in 4 patients and akinetic mutism in 1 patient; postoperative convulsion due to an inadvertent cortical venous injury in one patient resolved with medical treatment. Hydrocephalus developed in 2 patients; one patient needed placement of a ventriculoperitoneal shunt while the other responded to occasional lumbar punctures. Mortality or permanent morbidity did not occur. CONCLUSION: The horizontal head position may be an alternative for circumventing difficulties posed by the location of distal anterior cerebral artery aneurysms.

Ultrasound guidance in intracranial tumor resection: correlation with postoperative magnetic resonance findings.

PURPOSE: To determine the inter-method agreement between intraoperative ultrasonography and postoperative contrast-enhanced magnetic resonance imaging (MRI) in detecting tumor residue. MATERIAL AND METHODS: After resection was completed, the cavity borders of 32 tumors were examined with a 7 MHz intraoperative probe. Any echogenic region >5 mm in thickness extending from the surgical cavity into the brain substance was taken as the sonographic criterion for residual tumor. A continuous echogenic rim< 5 mm was considered normal. Results were correlated with gadolinium-enhanced MRI obtained within 48 h after surgery. RESULTS: The kappa value for inter-method agreement was 0.72. There were four cases in whom MRI showed residue despite a negative sonography: extensive edema or Surgicel along the cavity borders (three cases with glioblastoma multiforme) and the cystic component in the vicinity of cerebrospinal fluid (a case with pituitary macroadenoma) may be the reason for the residue going undetected. In a case with glioblastoma multiforme, residual enhancement was < 5 mm in thickness. CONCLUSION: Intraoperative ultrasound is an effective tool for maximizing the extent of intracranial tumor resection. Surgical use has to be minimized if intraoperative ultrasound is to be used as an adjunct to surgery. Tumors with preoperatively detected cystic components in the proximity of CSF-containing spaces have to be carefully evaluated with intraoperative ultrasound if residual cystic components are to be detected. A low-thickness echogenic rim should not be considered a reliable sign of the absence of residue.

Neuronavigation in skull base tumors.

OBJECTIVE: Computer-assisted neuronavigation was used in 87 cases of skull base lesions (SBLs). Preoperative planning and intraoperative identification of anatomic landmarks is especially important in SBLs since it helps to avoid or minimize surgical morbidity and mortality. In this study, we assessed the accuracy and the clinical usefulness of a frameless system based on the optical digitizer in SBLs. PATIENTS AND METHODS: Between April 2000 and March 2003, eighty-seven patients with SBLs were operated on in our department using cranial neuronavigation. A passive-marker-based neuronavigation system was used for intraoperative image guidance. There were 56 women and 31 men. The patient's ages ranged from 4 to 76 years (average: 45.7 year). The locations of the tumors reported in this series were as follows: frontobasal, 24 cases; sellar/parasellar, 32 cases; petroclival, 16 cases; tentorial/subtemporal, 15 cases. RESULTS: The computer-calculated registration accuracy ranged between 0.3 and 1.7 mm (mean, 1.1 mm). Gross total removal of the SBLs was accomplished in 82 out of 87 patients as was confirmed on postoperative CT and MRI scans. The follow-up period ranged from 1 month to 48 months (average: 20.1 months). Overall mortality and severe morbidity (meningitis, permanent cranial nerve deficits, and cerebrospinal fluid fistulae) rates were 4.6 % and 33.3 %, respectively. CONCLUSION: The image-guided surgery is a valuable aid for safe, helpful and complete removal of SBLs of the brain where accurate localization of the lesion is critical. Although our preliminary series is not large, interactive image guidance provides a constant display of surgical instrument position during surgery and its relationship with the SBLs components, surrounding normal brain, and vascular structures, providing valuable guidance to the surgeon during an operation. Our experience with the neuronavigation suggests that image guidance is helpful in this type of lesions, providing better anatomic orientation during skull base surgery, delineating tumor margins and their relation to critical neurovascular structures.

Successful surgical excision of juvenile-type spinal arteriovenous malformation in two stages following partial embolization.

The case of a 24-year-old man with a juvenile-type spinal arteriovenous malformation is reported. Spinal angiography and magnetic resonance image revealed a juvenile (Type III) AVM at the cervical spine. This spinal malformation was successfully resected with a posterior and anterior surgical approach in two stages following partial embolization.

Anterior cervical foraminotomy for unilateral spondylotic radiculopathy.

Anterior cervical foraminotomy (ACF) was developed under the concept of functional spine surgery, which directly eliminates compressive pathological factors while preserving functional anatomic features. The authors reviewed their results to determine the efficacy of the approach for unilateral cervical spondylotic radiculopathy (CSR). Nineteen patients were treated with the ACF with a follow-up from 12 to 36 months. There were 10 men and 9 women (mean age 49.8). Fourteen patients had a single ACF, and 5 had procedures at adjacent levels. The procedure involves microsurgical removal of the lateral portion of the uncinate process to identify the nerve root. Seventeen patients (89.5 %) were symptom-free or clearly improved, one (5.3 %) was unchanged and one patient (5.3 %) was worse in the visual analogue scale (VAS) score for radicular pain. One patient had developed contralateral foraminal stenosis at the level of the surgery and had undergone anterior discectomy and fusion. ACF provided good or excellent outcomes, with minimal morbidities, for patients with CSR. The advantages of ACF include direct decompression of the nerve root, and the preservation of the intervertebral disc and the motion segment. Thus, fusion-related sequelae, including graft-related complications, graft site complications and the adjacent level disease are avoided. The ACF procedure appears to be a good alternative for carefully selected patients with unilateral CSR.

The surgical management of traumatic C6 - C7 spondyloptosis in a patient without neurological deficits.

An unusual case of traumatic C6 - 7 total spondyloptosis with neurologically intactness at the time of injury is reported in a 35-year-old man. The patient was treated with a single-stage combined anterior-posterior and anterior operation to restore the cervical spondyloptosis, and creation of a three-column stabilization of the spine without neurological deficits. To the best of the authors' knowledge, there is no case report of traumatic spondyloptosis of cervical spine, presenting without neurological deficits in the pre- and postoperative periods. A brief summary of the clinical presentation, the surgical technique, and a review of the relevant literature are presented.

Post-operative sequential chemo-radiotherapy in high-grade cerebral gliomas with fotemustine.

High-grade gliomas are the most common primary brain tumors in adults. Twenty-seven patients with histopathologically proven anaplastic astrocytoma and glioblastoma multiforme were enrolled in this study from November 1998 to August 2002. Radiotherapy was administered after surgery and fotemustine (100 mg/m2) was sequentially administered every 3 weeks for 6 cycles. Overall, 111 cycles were administered to the 27 patients (median, 5 cycles; range, 1 to 6 cycles). Myelosuppression was mild to moderate. The median overall survival and progression free survival were 11+/-3.1 months (95%CI, 4.9-17.1) and 8+/-0.5 months (95%CI 7.1-8.9), respectively. One-year and two-year survivals were calculated at 48% and 7%, respectively. Significant prognostic factors (P<0.05) via univariate analysis were divided into two groups: completion of 6 cycles of chemotherapy versus incompletion of 6 cycles of chemotherapy. This trial demonstrates that postoperative radiotherapy and sequential fotemustine therapy is feasible, well tolerated, and may prolong survival in patients with newly diagnosed high-grade gliomas.

Is skull fracture necessary for developing an intradiploic pseudomeningocele as a complication of head injury in adulthood?

We report the case of an adult with a posttraumatic intradiploic pseudomeningocele which caused an expanded osteolytic skull lesion. Local pain and swelling, the only symptoms of the lesion, regressed after surgery. Intradiploic pseudomeningocele must be distinguished from intradiploic leptomeningeal cyst, which is of traumatic origin or arachnoid cyst and epidermoid cyst, which are of congenital origin. We also discuss the development of intradiploic pseudomeningoceleafter head trauma without skull fracture in adulthood and suggest a possible mechanism.

Nocardia brain abscess mimicking brain tumour in immunocompetent patients: report of two cases and review of the literature.

Nocardia brain abscess is a rare intracranial lesion and has been reported in immunocompromised patients. An optimal treatment approach has not been established. However, early diagnosis and appropriate antimicrobial therapy are very important factors for a good outcome. We report two unusual cases of Nocardia brain abscess simulating brain tumour in immunocompetent patients. One of the cases was presumed to be a primary brain tumour and the other a metastatic brain tumour. They underwent surgical gross total resection. After Nocardia asteroides was seen on Gram's stain and subsequently identified by culture, appropriate antibiotic therapy was initiated.

Successful surgical excision of a gigantic cerebral hydatid cyst.

In this study, an extremely rare case of a gigantic cerebral hydatid cyst is presented. A right frontotemporal hydatid cyst was detected by computed tomography and magnetic resonance imaging. This lesion was extirpated successfully with intact contents with the aid of a neuronavigation system. The literature is reviewed and possible postoperative complications are discussed with the published reports.

Surgical treatment of thalamic hematomas via the contralateral transcallosal approach.

Acute management of deep-seated hematomas remains controversial. Since patients with these hematoma later tend to develop severe edema and necrosis around the lesion, when surgery is indicated it should be done as early as possible. The purpose of this study was to compare whether early surgical removal and conservative treatment of primary thalamic hematoma correlated with improved neurological outcome. Last year, 61 patients with primary thalamic hematomas were admitted to our institution. Of these, 21 underwent surgery via contralateral transcallosal approach during the ultraearly stage (within 6 hours) after the apoplectic attack, and 24 patients were treated conservatively. Another 16 patients were excluded from the study due to systemic disease, mild hematoma (<40 cc), and deep coma associated with absence of brain stem reflexes. Initial Glasgow coma scores (GCS) at admission were similar for operated and nonoperated patients (8.64 +/- 1.93 versus 9.50 +/- 2.10, P>0.05). In the operated group, two patients had good recoveries and returned to normal life (Glasgow Outcome Score, or GOS, I), four had moderate disability and needed partial care (GOS II), six had severe disability and needed nursing care (GOS III), and six had a vegetative state (GOS IV). However, in the nonoperated group, one patient had good recovery and returned to normal life (GOS I), two had moderate disability and needed partial home care (GOS II), three had severe disability and needed nursing care (GOS III), and six had a vegetative state (GOS IV). In this group, the 30-day mortality rate was 50%. Mortality was markedly lower in the operated group (14.3%) than the nonoperated group. and this difference was statistically significant (chi2=3.33, P<0.05). From this study, we believe that evacuation of primary thalamic hematoma via the contralateral transcallosal microsurgical approach may be useful for deciding on the indication and predicting the functional prognosis.

Posterolaterally displaced type IIA odontoid fractures.

A case of type IIA odontoid fracture with posterolateral dislocation accompanied by spinal cord injury is presented. Cervical traction was employed but reduction could not be achieved with up to 8 kg of traction. The patient was treated with intraoperative reduction and C1-2 posterior transarticular screw fixation with supplemental bone-wire fusion, and rigid fixation was obtained without any complication.

Intradural lumbar disc herniation: report of two cases.

Intradural lumbar disc herniation (ILDH) is a rare pathology. The pathogenesis of ILDH is not known with certainty. Adhesions between the ventral wall of the dura and the posterior longitudinal ligament (PLL) could act as a preconditioning factor. Diagnosis of ILDH is difficult and seldom suspected preoperatively. Prompt surgery is necessary because the neurologic prognosis appears to be closely linked to preoperative duration of neurologic symptoms. Despite preoperatively significant neurological deficits, the prognosis following surgery is good. We report on two new cases of ILDH of high lumbar locations L1-2 and L2-3 with difficult differential diagnoses, and the possible pathogenic factors are discussed.

Hemilaminectomy for the removal of the spinal lesions.

OBJECTIVE: We evaluated 20 patients with spinal lesions with respect to the value of unilateral hemilaminectomy at the Department of Neurosurgery, Erciyes University, Medical Faculty, Kayseri, Turkey. The operative technique of the limited approach for spinal lesions is described. METHODS: The study is based on 20 prospective consecutive patients with spinal lesions who had unilateral hemilaminectomy. There were 12 women and eight men. Age ranged from 17 to 63 years mean (42 years) with a slight preponderance of women patients (60%). Spinal lesions were cervical in three cases, lumbar in five cases, and thoracic in 12 cases. Hemilaminectomy was performed by using a high speed drill. RESULTS: Postoperative neurological status was unchanged in six cases, improved in 11 cases, and worsened in three cases. We only observed two cases of wound infections that were not related to our surgical approach. At the follow-up evaluation, which occurred approximately 25 months after surgery none of the patients showed spinal deformity or spinal instability. CONCLUSION: The rationale of attempting unilateral approach is to avoid damage to the dorsal static structures of the vertebral column. With the precise preoperative definition of the relationship of tumor to the surface of the spinal cord by contrast enhanced MRI, unilateral approaches might be more applicable to spinal lesions except invasive extradural lesions.

Effect of EGb-761 on vasospasm in experimental subarachnoid hemorrhage.

Based on the previously suggested hypothesis that the generation of free radicals leading to lipid peroxidation is involved in the genesis of vasospasm and vasculopathy following subarachnoid hemorrhage, the therapeutic effect of EGb 761 as an antioxidant on experimental vasospasm and vasculopathy was evaluated in a double hemorrhage dog model of chronic cerebral vasospasm. For this study 14 dogs were randomly assigned to two groups, a control and a Ginkgo biloba group. The control group was only administered saline in a volume equivalent to a dose of 100 mgEGb 761/kg while the treatment group was given 100 mg EGb 761/kg. The diameter of the basilar artery decreased from 1.95 +/- 0.16 mm at day 0 to 1.11 +/- 0.07 mm at day 8 in the control group, while in the treatment group the vessel diameter decreased from 2.01 +/- 0.17 mm at day 0 to 1.72 +/- 0.16 mm at day 8. These results correspond a decrease in vessel diameter of 15.1% in the treatment group and of 43.1% in the control group (P < 0.05). Histopathological studies of the specimens obtained from basilar arteries showed that pathological signs of proliferative vasculopathy, including narrowing of the vessel lumen, corrugation of the lamina elastica and subendothelial thickening, were present in all the animals in the control group, while they could not be demonstrated in the Ginkgo biloba group. These results suggest that Ginkgo biloba may have a protective effect against subarachnoid hemorrhage-induced vasospasm and vasculopathy as a result of antioxidants.

Therapeutic effect of tirilazad mesylate (U-74006F), mannitol, and their combination on experimental ischemia.

The effect of tirilazad mesylate (U-74006F), mannitol, and their combination was investigated on focal cerebral ischemia induced by permanent middle cerebral artery (MCA) occlusion in rabbits. Rabbits were divided into four groups receiving vehicle, U-74006F, mannitol, and U-74006F plus mannitol. Hematocrit (hct), glucose, mean arterial blood pressure (MABP), pH, PCO2, and PO2 were measured both before and after occlusion. Seventy-two hours following the permanent MCA occlusion, the neurological outcome was assessed and a quantitative neuropathologic examination was performed in all rabbits. The neurological outcome was better in the rabbits treated with U-74006F plus mannitol than in the other groups. The size of infarction of the affected hemisphere following MCA occlusion was 49.7% in the control group, 30.6% in the U-74006F group, 47.6% in the mannitol group, and 24.1% in the U-74006F plus mannitol group. There was a statistically significant reduction in infarct size in the U-74006F plus mannitol group compared with the other groups (P < 0.05). The ratio of ischemic neurons to total neurons in the cortex was smaller in the U-74006F plus mannitol group than in the other groups. The ratio of ischemic neurons to total neurons in the subcortex was significantly lower in the U-74006F plus mannitol group than in the other groups (P < 0.05). Our data provide evidence for the beneficial effects of both U-74006F and U-74006F plus mannitol in promoting neurological recovery and preservation of the ischemic area.

Successful surgical treatment of a thalamic hydatid cyst with contralateral transcallosal approach. Case report and review of the literature.

An extremely rare case of a thalamic hydatid cyst is presented and the literature is reviewed. A right thalamic hydatid cyst without rim enhancement or perifocal edema was detected by computed tomography and magnetic resonance. This lesion was extirpated successfully with intact contents via contralateral transcallosal approach. To our knowledge, this is the second hydatid cyst of the thalamus, an unusual location, and the first hydatid cyst to be removed completely with intact contents reported in the literature.

Failure of open third ventriculostomy for shunt infections in infants.

Open third ventriculostomy (OTV) was performed on 4 infants with noncommunicating hydrocephalus and intractable shunt infections. All patients were resistant or relapsed after treatment with intravenous and intraventricular antibiotics along with change of the shunt apparatus. We performed phase-contrast cine magnetic resonance imaging (MRI) for preoperative and postoperative evaluation of cerebrospinal fluid (CSF) flow at the aqueduct of Sylvius. All patients required a second OTV approximately 3 weeks after the first OTV due to closure of the patency. Our experience led us to view OTV as an unsuccessful procedure in infantile noncommunicating hydrocephalus due to an insufficiently developed subarachnoid space. The patients' data, operative findings and probable causes of failure are presented here.