Sam Safavi-Abbasi

The frequency and clinical significance of congenital defects of the posterior and anterior arch of the atlas

OBJECT In this study the authors investigated the anatomical, clinical, and imaging features as well as incidence of congenital defects of the C-1 arch. METHODS The records of 1104 patients who presented with various medical problems during the time between January 2006 and December 2006 were reviewed retrospectively. The craniocervical computed tomography (CT) scans obtained in these patients were evaluated to define the incidence of congenital defects of the posterior arch of C-1. In addition, 166 dried C-1 specimens and 84 fresh human cadaveric cervical spine segments were evaluated for anomalies of the C-1 arch. RESULTS Altogether, 40 anomalies (2.95%) were found in 1354 evaluated cases. Of the 1104 patients in whom CT scans were acquired, 37 (3.35%) had congenital defects of the posterior arch of the atlas. The incidence of each anomaly was as follows: Type A, 29 (2.6%); Type B, six (0.54%); and Type E, two (0.18%). There were no Type C or D defects. One patient (0.09%) had an anterior arch cleft. None of the reviewed patients had neurological deficits or required surgical intervention for their anomalies. Three cases of Type A posterior arch anomalies were present in the cadaveric specimens. CONCLUSIONS Most congenital anomalies of the atlantal arch are found incidentally in asymptomatic patients. Congenital defects of the posterior arch are more common than defects of the anterior arch.

Supracerebellar infratentorial approach to cavernous malformations of the brainstem: surgical variants and clinical experience with 45 patients.

OBJECTIVEThe supracerebellar infratentorial (SCIT) approach can be performed at the midline (median variant), lateral to the midline (paramedian variant), or at the level of the angle formed by the transverse and sigmoid sinuses (extreme lateral variant). We analyzed our experience with SCIT approaches for the surgical treatment of cavernous malformations of the brainstem (CMBs). METHODSDemographic, clinical, radiologic, and surgical data from 45 patients (20 males and 25 females; mean age, 36.2 years) with CMBs surgically removed through SCIT approaches were reviewed retrospectively. Anatomic information was explored using cadaver head dissection. RESULTSTwenty-three lesions were in the midbrain, 3 were at the midbrain and extended to the thalamus, 9 were at the pontomesencephalic junction, and 10 were in the upper pons. All patients presented with hemorrhage. The median variant was used in 13 patients, the paramedian variant in 9, and the extreme lateral variant in 23. Intraoperatively, all CMBs were associated with a developmental venous anomaly. At last follow-up, 88% of the patients were the same or better. After a mean follow-up of 20 months, their mean Glasgow Outcome Scale score was 4.1. CONCLUSIONSCIT approaches provide excellent exposure to CMBs located at the posterior incisural space, not only in the midline but also in the posterolateral surface of the upper pons and midbrain. Careful preoperative planning and neuronavigational assistance are needed to determine the best angle of attack and trajectory for SCIT approaches. Refined microsurgical techniques are paramount to achieve safe surgical removal of CMBs with good outcomes.

Microsurgical management of spinal schwannomas: evaluation of 128 cases.

OBJECT The authors conducted a study to evaluate the clinical characteristics and surgical outcomes in patients with spinal schwannomas and without neurofibromatosis (NF). METHODS The data obtained in 128 patients who underwent resection of spinal schwannomas were analyzed. All cases with neurofibromas and those with a known diagnosis of NF Type 1 or 2 were excluded. Karnofsky Performance Scale (KPS) scores were used to compare patient outcomes when examining the anatomical location and spinal level of the tumor. The neurological outcome was further assessed using the Medical Research Council (MRC) muscle testing scale. RESULTS Altogether, 131 schwannomas were treated in 128 patients (76 males and 52 females; mean age 47.7 years). The peak prevalence is seen between the 3rd and 6th decades. Pain was the most common presenting symptom. Gross-total resection was achieved in 127 (97.0%) of the 131 lesions. The nerve root had to be sacrificed in 34 cases and resulted in minor sensory deficits in 16 patients (12.5%) and slight motor weakness (MRC Grade 3/5) in 3 (2.3%). The KPS scores and MRC grades were significantly higher at the time of last follow-up in all patient groups (p = 0.001 and p = 0.005, respectively). CONCLUSIONS Spinal schwannomas may occur at any level of the spinal axis and are most commonly intradural. The most frequent clinical presentation is pain. Most spinal schwannomas in non-NF cases can be resected totally without or with minor postoperative deficits. Preoperative autonomic dysfunction does not improve significantly after surgical management.

Surgical management and outcome of schwannomas in the craniocervical region

OBJECT Schwannomas occupying the craniocervical junction (CCJ) are rare and usually originate from the jugular foramen, hypoglossal nerves, and C-1 and C-2 nerves. Although they may have different origins, they may share the same symptoms, surgical approaches, and complications. An extension of these lesions along the posterior fossa cisterns, foramina, and spinal canal--usually involving various cranial nerves (CNs) and the vertebral and cerebellar arteries--poses a surgical challenge. The primary goals of both surgical and radiosurgical management of schwannomas in the CCJ are the preservation and restoration of function of the lower CNs, and of hearing and facial nerve function. The origins of schwannomas in the CCJ and their clinical presentation, surgical management, adjuvant stereotactic radiosurgery, and outcomes in 36 patients treated at Barrow Neurological Institute (BNI) are presented. METHODS Between 1989 and 2009, 36 patients (mean age 43.6 years, range 17-68 years) with craniocervical schwannomas underwent surgical resection at BNI. The records were reviewed retrospectively regarding clinical presentation, radiographic assessment, surgical approaches, adjuvant therapies, and follow-up outcomes. RESULTS Headache or neck pain was present in 72.2% of patients. Cranial nerve impairments, mainly involving the vagus nerve, were present in 14 patients (38.9%). Motor deficits were found in 27.8% of the patients. Sixteen tumors were intra- and extradural, 15 were intradural, and 5 were extradural. Gross-total resection was achieved in 25 patients (69.4%). Adjunctive radiosurgery was used in the management of residual tumor in 8 patients; tumor control was ultimately obtained in all cases. CONCLUSIONS Surgical removal, which is the treatment of choice, is curative when schwannomas in the CCJ are excised completely. The far-lateral approach and its variations are our preferred approaches for managing these lesions. Most common complications involve deficits of the lower CNs, and their early recognition and rehabilitation are needed. Stereotactic radiosurgery, an important tool for the management of these tumors as adjuvant therapy, can help decrease morbidity rates.

Biomechanical effects of laminoplasty versus laminectomy: stenosis and stability.

Study Design. In vitro human cadaveric study simultaneously quantifying sagittal plane flexibility and spinal canal stenosis. Objective. To compare biomechanical stability and the change in cross-sectional area during flexion and extension after laminectomy and open-door laminoplasty. Summary of Background Data. Spinal canal stenosis has been quantified in vitro but has not been quantified in studies of laminectomy or laminoplasty. Methods. Cadaveric specimens were loaded in physiologic-range flexion and extension using nonconstraining pure moments while recording segmental angles optoelectronically. Custom flexible tubing was placed within the spinal canal, and water was continuously pumped through the tubing while measuring upstream pressure. Spinal canal cross-sectional area correlated to water pressure, allowing continuous monitoring of the smallest cross-sectional area of the canal. Specimens were tested (1) normal, (2) after modeling stenosis by inserting hemispherical wooden beads in the spinal canal at 3 levels, (3) after open-door laminoplasty at 5 levels, and (4) after expanding laminoplasty to laminectomy. Results. Range of motion (ROM) in the normal, stenotic, and laminoplasty conditions did not differ significantly. However, laminectomy increased ROM significantly more than other conditions. ROM after laminectomy was 13% greater than after laminoplasty. After modeling stenosis, the cross-sectional area decreased to 52% ± 12% of normal. Laminoplasty restored the cross-sectional area to 70% ± 12% of normal whereas laminectomy restored cross-sectional area to 101% ± 4% of normal. Among all conditions, areas differed significantly except normal versus laminectomy. Conclusion. Laminoplasty leaves the spine in a significantly more stable condition than laminectomy. However, laminoplasty failed to relieve stenosis completely. In this study, stenosis was modeled as about 50% occlusion of the spinal canal. The degree of stenosis should be considered in clinical decisions of whether laminectomy or laminoplasty is more appropriate.

Image-Guided Lateral Suboccipital Approach: Part 2—Impact on Complication Rates and Operation Times

OBJECTIVE Image-guidance systems are widely available for surgical planning and intraoperative navigation. Recently, three-dimensional volumetric image rendering technology that increasingly applies in navigation systems to assist neurosurgical planning, e.g., for cranial base approaches. However, there is no systematic clinical study available that focuses on the impact of this image-guidance technology on outcome parameters in suboccipital craniotomies. METHODS A total of 200 patients with pathologies located in the cerebellopontine angle were reviewed, 100 of whom underwent volumetric neuronavigation and 100 of whom underwent treatment without intraoperative image guidance. This retrospective study analyzed the impact of image guidance on complication rates (venous sinus injury, venous air embolism, postoperative morbidity caused by venous air embolism) and operation times for the lateral suboccipital craniotomies performed with the patient in the semi-sitting position. RESULT This study demonstrated a 4% incidence of injury to the transverse-sigmoid sinus complex in the image-guided group compared with a 15% incidence in the non-image-guided group. Venous air embolisms were detected in 8% of the image-guided patients and in 19% of the non-image-guided patients. These differences in terms of complication rates were significant for both venous sinus injury and venous air embolism (P < 0.05). There was no difference in postoperative morbidity secondary to venous air embolism between both groups. The mean time for craniotomy was 21 minutes in the image-guided group and 39 minutes in non-image-guided group (P = 0.036). CONCLUSION Volumetric image guidance provides fast and reliable three-dimensional visualization of sinus anatomy in the posterior fossa, thereby significantly increasing speed and safety in lateral suboccipital approaches.

Thrombophilia Due to Factor V and Factor II Mutations and Formation of a Dural Arteriovenous Fistula: Case Report and Review of a Rare Entity

Genetic mutations underlying thrombophilia are often recognized in patients with thromboembolic episodes. However, the clinical and therapeutic implications of such findings often remain unclear. We report the first case of a dural arteriovenous fistula (DAVF) in a patient with a combined factor II and factor V Leiden mutation. A 40-year-old man presented with a large left temporal and intraventricular hemorrhage. An initial angiogram showed thrombosis of the left sigmoid sinus but no evidence of a vascular malformation. One year after the hemorrhage, an angiographic study showed the appearance of a right DAVF. During the follow-up period, the patient was found to harbor heterozygosity for a mutation of factor V and a mutation of factor II. Recognition of the patients thrombophilia led to prolonged oral anticoagulation therapy to reduce the risk of a recurrent thrombotic episode. Despite the increased risk of bleeding, the therapy was considered justified. DAVFs may occur after sinus thrombosis in patients with combined factor II and factor V mutations. This observation indicates the association of multiple hematological disorders with DAVFs in individual patients. Moreover, it raises the clinical conundrum of how to manage patients with thrombophilia, intracranial hemorrhage, and DAVFs.

Meta-analysis and systematic review of risk factors for shunt dependency after aneurysmal subarachnoid hemorrhage

OBJECTIVE Aneurysmal subarachnoid hemorrhage (aSAH) may be complicated by hydrocephalus in 6.5%-67% of cases. Some patients with aSAH develop shunt dependency, which is often managed by ventriculoperitoneal shunt placement. The objectives of this study were to review published risk factors for shunt dependency in patients with aSAH, determine the level of evidence for each factor, and calculate the magnitude of each risk factor to better guide patient management. METHODS The authors searched PubMed and MEDLINE databases for Level A and Level B articles published through December 31, 2014, that describe factors affecting shunt dependency after aSAH and performed a systematic review and meta-analysis, stratifying the existing data according to level of evidence. RESULTS On the basis of the results of the meta-analysis, risk factors for shunt dependency included high Fisher grade (OR 7.74, 95% CI 4.47-13.41), acute hydrocephalus (OR 5.67, 95% CI 3.96-8.12), in-hospital complications (OR 4.91, 95% CI 2.79-8.64), presence of intraventricular blood (OR 3.93, 95% CI 2.80-5.52), high Hunt and Hess Scale score (OR 3.25, 95% CI 2.51-4.21), rehemorrhage (OR 2.21, 95% CI 1.24-3.95), posterior circulation location of the aneurysm (OR 1.85, 95% CI 1.35-2.53), and age ≥ 60 years (OR 1.81, 95% CI 1.50-2.19). The only risk factor included in the meta-analysis that did not reach statistical significance was female sex (OR 1.13, 95% CI 0.77-1.65). CONCLUSIONS The authors identified several risk factors for shunt dependency in aSAH patients that help predict which patients are likely to require a permanent shunt. Although some of these risk factors are not independent of each other, this information assists clinicians in identifying at-risk patients and managing their treatment.

Has management of epidermoid tumors of the cerebellopontine angle improved? A surgical synopsis of the past and present.

We compared the surgical outcomes of recent patients with cerebellopontine angle (CPA) epidermoids treated with advanced surgical tools with those of patients treated in earlier series. From November 2000 to June 2004, we treated 12 patients with epidermoid tumors. One patient had a strict CPA lesion. Tumors extended into the prepontine region in seven cases and supratentorially in two. In two cases the CPA was involved bilaterally. All patients but one underwent a lateral suboccipital approach in a semi-sitting position with microsurgical technique. Endoscopic assistance was used in cases with extensions beyond the CPA. In one case, a subtemporal route was used. The mean follow-up was 27 months (range, 8 to 50 months). There were no deaths. Total removal was achieved in 7 of the 10 patients with unilateral CPA epidermoids. Preoperative status improved in eight (80%) patients, particularly the function of cranial nerves (CNs) V and VII. Only two patients had permanent CN deficits. Complete excision with preservation of CN function should be the goals of management of epidermoids of the CPA. In some cases, these goals can be difficult to achieve, even with contemporary surgical equipment. Bilateral and extensive tumors should be removed in staged procedures. The function of CN V and CN VII may recover after decompression, but the outcome of symptoms related to CN VIII is less certain. The endoscope is a reliable tool for assessing the extension of epidermoids, but it cannot be used for tumor removal.

The ascending pharyngeal artery and its relevance for neurosurgical and endovascular procedures.

OBJECTIVE The ascending pharyngeal artery (APA), a branch of the external carotid artery (ECA), supplies the lower cranial nerves, superior cervical ganglion, and nasopharyngeal structures. The APA can also supply blood to various intracranial lesions. We studied the anatomy of the APA in the context of its neurosurgical and endovascular relevance. METHODS The cervical origin, branching pattern, and course of the APA were studied in 20 human cadaveric craniocervical sides. The diameter of the APA, the extension of its main trunk, and the distance of its origin from the common carotid artery bifurcation were measured. The relationships between the APA and surrounding structures were also observed. RESULTS In 80% of the specimens, the APA originated from the ECA. It originated from its medial wall in 56% and from the posterior wall in 44%. The APA originated from the internal carotid artery, common carotid artery bifurcation, occipital artery, and a trunk common to the lingual and facial arteries in 5% each. The APA was usually the third branch of the ECA (40%). The mean distance from the origin of the APA to the common carotid artery bifurcation was 15.3 mm (range, 0–32; standard deviation, ± 8.3 mm). The APA was frequently the second smallest branch of the ECA (caliber, 1.54 mm; range, 1.1–2.1; standard deviation, ± 0.25 mm). CONCLUSION The APA is an important channel for supplying neural structures of the posterior fossa. Knowledge of its anatomy, variants, and anastomotic channels is essential in the treatment of lesions supplied by its branches and to avoid complications related to its inadvertent injury.