Nicholas C. Bambakidis
Stereotactic radiosurgery for arteriovenous malformations
Nicholas C. Bambakidis and Warren R. Selman
Nicholas C. Bambakidis, Simon S. Lo and Warren R. Selman
Nicholas C. Bambakidis, Rui-Zhen Wang, Linda Franic and Robert H. Miller
The glycoprotein molecule sonic hedgehog (Shh) has been shown to play a critical role in neuraxial development. To assess its role in the repair of demyelination following spinal cord injury (SCI), escalating doses of Shh were injected into demyelinated lesions in adult rat spinal cords.
Twenty-seven adult rats underwent thoracic laminectomy and chemical demyelination of the spinal cord dorsal columns without neurological deficit. A subset of 20 rats was treated after 3 days by direct injection of Shh at two different doses. Rats were killed at 7 or 21 days after SCI, and tissue samples underwent immediate fixation or were placed into cell culture. Diffuse cellular proliferative responses throughout the gray and white matter were observed in up to 70% of Shh-treated rats. Proliferation around the central canal, believed to be derived from the ventricular ependyma consistent with neuronal stem cell induction, was demonstrated in up to 60% of the treated rats. No significant proliferation in these areas was detected in control rats. Dorsal areas of nestin-positive cells were also observed in 70% of rats treated with high doses of Shh, and these observations were reproduced in cell culture as well as in cultures of dorsal spinal cord explants. Cell counts revealed significant increases in the percentage of oligodendrocyte precursors and neurons in treated compared with control rats.
Exogenous Shh administration promotes nestin-positive cell proliferation after SCI in adult rodents. These cells are believed to be derived from neural precursor cells. The populations of oligodendrocyte precursors and neurons were likewise increased in Shh-treated rats, suggesting that these cells may be derived from neural stem cells.
Yifei Duan, Carlito Lagman, Raleigh Ems and Nicholas C. Bambakidis
The exact pathophysiological mechanisms underlying cerebral aneurysm formation remain unclear. Asymmetrical local vascular geometry may play a role in aneurysm formation and progression. The object of this study was to investigate the association between the geometric asymmetry of the middle cerebral artery (MCA) and the presence of MCA aneurysms and associated high-risk features.
Using a retrospective case-control study design, the authors examined MCA anatomy in all patients who had been diagnosed with an MCA aneurysm in the period from 2008 to 2017 at the University Hospitals Cleveland Medical Center. Geometric features of the MCA ipsilateral to MCA aneurysms were compared with those of the unaffected contralateral side (secondary control group). Then, MCA geometry was compared between patients with MCA aneurysms and patients who had undergone CTA for suspected vascular pathology but were ultimately found to have normal intracranial vasculature (primary control group). Parent vessel and aneurysm morphological parameters were measured, calculated, and compared between case and control groups. Associations between geometric parameters and high-risk aneurysm features were identified.
The authors included 247 patients (158 cases and 89 controls) in the study. The aneurysm study group consisted of significantly more women and smokers than the primary control group. Patients with MCA bifurcation aneurysms had lower parent artery inflow angles (p = 0.01), lower parent artery tortuosity (p < 0.01), longer parent artery total length (p = 0.03), and a significantly greater length difference between ipsilateral and contralateral prebifurcation MCAs (p < 0.01) than those in primary controls. Type 2 MCA aneurysms (n = 89) were more likely to be associated with dome irregularity or a daughter sac and were more likely to have a higher cumulative total of high-risk features than type 1 MCA aneurysms (n = 69).
Data in this study demonstrated that a greater degree of parent artery asymmetry for MCA aneurysms is associated with high-risk features. The authors also found that the presence of a long and less tortuous parent artery upstream of an MCA aneurysm is a common phenotype that is associated with a higher risk profile. The aneurysm parameters are easily measurable and are novel radiographic biomarkers for aneurysm risk assessment.
Nicholas C. Bambakidis and Warren R. Selman
Sunil Manjila, Shakeel A. Chowdhry, Nicholas C. Bambakidis and David J. Hart
The authors present a case of traumatic, complete, high cervical spine injury in a patient with gradual worsening deformity and neck pain while in rigid cervical collar immobilization, ultimately resulting in coronal-plane spondyloptosis. Due to the extent of lateral displacement of the spinal elements, preoperative evaluation included catheter angiography, which revealed complete right vertebral artery (VA) occlusion. A prophylactic arterial bypass graft from the right occipital artery to the extradural right VA was fashioned to augment posterior circulation blood supply prior to reduction and circumferential instrumented fusion. Following surgery, the patient was able to participate in an aggressive rehabilitation program allowing early mobilization, and he ceased to be ventilator-dependent following implantation of a diaphragmatic pacer. The authors review factors leading to progression of this type of injury and suggest technical pearls as well as highlight specific management pitfalls, including operative risks.
Nicholas C. Bambakidis, Tina Rodrigue, Cliff A. Megerian and Robert A. Ratcheson
✓ Endolymphatic sac tumors (ELSTs) are aggressive papillary lesions of the temporal bone. Although histologically benign, they may exhibit invasive growth and destruction of the skull base. Patients generally present with symptoms referable to the lesion's location within the middle or posterior cranial fossa. Although well characterized as a distinct entity, ELSTs involved in metastatic dissemination have never been reported. In the present report the authors describe a case of ELST metastatic to the spine treated with resection.
L. Fernando Gonzalez, Sepideh Amin-Hanjani, Nicholas C. Bambakidis and Robert F. Spetzler
Posterior circulation lesions constitute approximately 10% of all intracranial aneurysms. Their distribution includes the basilar artery (BA) bifurcation, superior cerebellar artery, posterior inferior cerebellar artery, and anterior inferior cerebellar artery. The specific features of a patient's aneurysm and superb anatomical knowledge help the surgeon to choose the most appropriate approach and to tailor it to the patient's situation. The main principle that must be applied is maximization of bone resection. This allows the surgeon to work within a wider corridor, which facilitates the use of surgical instruments and minimizes retraction of the brain.
The management of aneurysms within the posterior circulation requires expertise in skull base and vascular surgery. Endovascular treatments have become increasingly important, but in this paper the authors focus on the surgical management of these difficult aneurysms. The paper is divided into three parts: the first section is a brief review of the anatomy of the BA; the second part is a review of the techniques associated with the management of posterior fossa aneurysms; and in the third section the authors describe the different approaches, their nuances and indications based on the location of the aneurysm, and its relationship to the surrounding bone (especially the clivus, dorsum sellae, and the free edge of the petrous apex).