Biomedical subjects

Stephen B Lewis

Publications and source records attributed to Stephen B Lewis.

7 recordsLinked to original sources

PubMed2006

Intraoperative dynamic angiography to detect resolution of Bow Hunter's syndrome: Technical case report.

BACKGROUND: Bow Hunter's syndrome is a rare form of vertebrobasilar insufficiency that may be successfully treated by surgical intervention. Use of intraoperative dynamic transcranial Doppler ultrasound for surgical treatment of vertebrobasilar insufficiency has been described in literature. However, this technique was inconsistent and unreliable in some patients. We present a case of a patient with Bow Hunter's syndrome treated surgically and emphasize the valuable addition of intraoperative dynamic angiography to determine resolution of vertebral artery compromise. CASE DESCRIPTION: The patient was a 58-year-old man with complaints of dizziness, vertigo, and near-syncopal episodes that occurred when he rotated his head to the left. Imaging revealed compromise of the dominant left vertebral artery with leftward head rotation. An anterior cervical approach with decompression of the left subaxial vertebral artery was performed. Significant osteophyte formation was observed. Removal of bone and decompression of the vertebral artery was performed. Intraoperative dynamic angiography confirmed resolution of vertebral artery compression and minimized the amount of decompression. No further intervention was required. CONCLUSION: Intraoperative dynamic angiography is a definitive test to determine hemodynamic resolution of Bow Hunter's syndrome. It offers real-time feedback of vertebral artery decompression, potentially minimizes the amount of decompression, and can be performed safely.

Axis, Cervical Vertebra↗

PubMed2006

One-piece versus two-piece orbitozygomatic craniotomy: quantitative and qualitative considerations.

OBJECTIVE: The orbitozygomatic (OZ) craniotomy minimizes brain retraction and improves cranial base exposure by providing a multidirectional view, increased operative angles and working space. The two main variations of the approach include the one-piece and the two-piece types. The microsurgical anatomy of the one- and two-piece OZ craniotomies are presented with the goal of comparing the extent of orbital roof removal between these two craniotomies and the effect of orbital roof removal on operative exposure. METHODS: Ten two-piece and 11 one-piece OZ craniotomies were performed in a stepwise manner simulating the approaches on formalin fixed specimens. The orbital surface area removed above the frontozygomatic suture extending medially over the orbital roof was measured from each bone flap. The two-sided unpaired t test using STATA 7.0 software was used to compare the amount of orbital roof removed using the two approaches. RESULTS: The two-piece OZ craniotomy allowed for the removal of a larger portion of the roof and lateral wall of the orbit than the one-piece. The total orbitotomy, including the orbital roof plus the part of the lateral wall above the frontozygomatic suture, had an average surface area of 996 +/- 229 mm for the two piece and 372 +/- 103 mm for the one-piece. The orbital roof made up 27 +/- 18% of the orbital osteotomy for the one-piece craniotomies and 67 +/- 10% of the osteotomy for the two-piece craniotomies (P < 0.001). CONCLUSION: The two-piece OZ craniotomy allows for more extensive orbital roof removal and better visualization of the basal frontal lobe. Therefore, the two-piece may result in a lower incidence of enophtalmus and poor cosmetic outcomes, particularly if the remaining orbital roof must be removed piecemeal during the one-piece OZ craniotomy in order to obtain satisfactory exposure.

Craniotomy↗

PubMed2005

Skull base chordoma.

PURPOSE: Our purpose was to discuss the optimal treatment and outcomes for patients with skull base chordomas. METHODS: We reviewed the pertinent literature for this study. RESULTS: Skull base chordomas usually arise in the clivus and are rarely completely resectable. Therefore, most are treated with radiotherapy (RT). Because of the risk of severe late complications, the dose is often limited with conventional photon RT, and the probability of cure is low. Proton RT alone or combined with photon RT (proton/photon RT) offers the advantage of improved dose distribution and the ability to treat the tumor to a higher dose without exceeding normal tissue tolerance. The 10-year local control rate after proton/photon RT is approximately 40% to 50%. The probability of local control is related to minimum tumor dose and dose inhomogeneity. CONCLUSIONS: Skull base chordoma is a rare neoplasm that is rarely cured after surgery alone or combined with conventional RT. Proton/photon RT offers the advantage of increasing the tumor dose while minimizing the dose to normal tissues, thus reducing the risk of late complications. The optimal treatment may be photon/proton RT alone or combined with a gross total resection, when feasible.

Chordoma↗

PubMed2005

Proteomic identification of biomarkers of traumatic brain injury.

Traumatic brain injury (TBI) is a major national health problem without a US Food and Drug Administration-approved therapy. This review summarizes the importance of discovering relevant TBI protein biomarkers and presents logical rationale that neuroproteomic technologies are uniquely suited for the discovery of otherwise unnoticed TBI biomarkers. It highlights that one must make careful decisions when choosing which paradigm (human vs. animal models) and which biologic samples to use for such proteomic studies. It further outlines some of the desirable attributes of an ideal TBI biomarker and discusses how biomarkers discovered proteomically are complementary to those identified by traditional approaches. Lastly, the most important sequela of any proteomically identified TBI biomarker is validation in preclinical or clinical samples.

Animals↗

PubMed2002

Distal posterior inferior cerebellar artery aneurysms: clinical features and management.

OBJECT: Aneurysms located on the distal portion of the posterior inferior cerebellar artery (PICA) are uncommon, and their underlying pathology, natural history, and clinical management are poorly understood. To clarify these lesions more fully, the authors undertook a retrospective analysis of the clinical features and management results of 22 distal PICA aneurysms in 20 consecutive patients treated at one institution by the same surgeon during the past decade. METHODS: The series included 10 men and 10 women (mean age at presentation 51 years). Nine patients presented with only subarachnoid and/or intraventricular hemorrhage (median Hunt and Hess Grade II). In seven patients intracerebellar hemorrhage was also found; two patients presented with pressure effects and two hemorrhages were incidentally discovered. Prominent comorbidities included cigarette smoking (50%) and hypertension (50%). The 13 saccular and nine fusiform distal PICA aneurysms were distributed on the following segments of the PICA: lateral medullary (seven lesions), tonsillomedullary (five lesions), telovelotonsillar (five lesions), and cortical (five lesions). Six oases were associated with cerebellar arteriovenous malformations. Skull-base and far-lateral transcondylar surgical approaches were used to secure the aneurysms in 86% of cases, either by direct clipping (13 lesions), vessel sacrifice (four lesions), or vessel sacrifice plus bypass (two lesions). Two aneurysms were treated using endovascular PICA ablation. Overall outcome at hospital discharge was excellent or good in 70% of cases. At long-term follow up (100% of patients, mean 123 days), an excellent or good outcome had been achieved in 85% of cases. CONCLUSIONS: Depending on the PICA segment that was affected, variations in clipping strategies and surgical exposures aimed at the PICA branch and main trunk preservation were major contributors to good long-term results.

Adult↗

PubMedDate not supplied

Her vision was tied down.

A 50-year-old female presented with progressive painless vision loss in the left eye and was subsequently diagnosed to have a pituitary macroadenoma, consistent with a prolactinoma, which was compressing the chiasm primarily on the left and involving the left cavernous sinus. She was treated with oral bromocriptine, resulting in marked shrinkage of the tumor and significant visual field recovery. Subsequently, she again began noting progressive vision loss in both eyes and was initially thought to have pituitary tumor regrowth. Repeat brain MRI, however, showed chiasmal prolapse with inferior tethering into an empty sella. Surgical fat padding to reposition the chiasm resulted in visual improvement with a different visual field pattern in the left eye. The clinical manifestations and etiopathogenesis of the empty sella syndrome are discussed.

Adipose Tissue↗

PubMedDate not supplied

That's a wrap.

Muslin-induced optochiasmatic arachnoiditis is a rare complication following surgical repair of an intracranial aneurysm but should be suspected in any delayed visual loss after aneurysm repair in which muslin was used. A 52-year-old male underwent clipping and muslin wrapping of a ruptured aneurysm of an anterior communicating artery. Eight months following surgery, the patient developed progressive visual loss, resulting in a bitemporal hemianopsia. Neuroimaging confirmed a suprasellar mass but no recurrent aneurysm. The patient was treated with prednisone and had significant improvement of his vision. Muslin wrapping of aneurysms should probably be avoided in aneurysms near the optic apparatus.

Arachnoiditis↗