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Michael A. Bohl, Nikolay L. Martirosyan, Zachary W. Killeen, Evgenii Belykh, Joseph M. Zabramski, Robert F. Spetzler and Mark C. Preul

Despite an overwhelming history demonstrating the potential of hypothermia to rescue and preserve the brain and spinal cord after injury or disease, clinical trials from the last 50 years have failed to show a convincing benefit. This comprehensive review provides the historical context needed to consider the current status of clinical hypothermia research and a view toward the future direction for this field. For millennia, accounts of hypothermic patients surviving typically fatal circumstances have piqued the interest of physicians and prompted many of the early investigations into hypothermic physiology. In 1650, for example, a 22-year-old woman in Oxford suffered a 30-minute execution by hanging on a notably cold and wet day but was found breathing hours later when her casket was opened in a medical school dissection laboratory. News of her complete recovery inspired pioneers such as John Hunter to perform the first complete and methodical experiments on life in a hypothermic state. Hunter’s work helped spark a scientific revolution in Europe that saw the overthrow of the centuries-old dogma that volitional movement was created by hydraulic nerves filling muscle bladders with cerebrospinal fluid and replaced this theory with animal electricity. Central to this paradigm shift was Giovanni Aldini, whose public attempts to reanimate the hypothermic bodies of executed criminals not only inspired tremendous scientific debate but also inspired a young Mary Shelley to write her novel Frankenstein. Dr. Temple Fay introduced hypothermia to modern medicine with his human trials on systemic and focal cooling. His work was derailed after Nazi physicians in Dachau used his results to justify their infamous experiments on prisoners of war. The latter half of the 20th century saw the introduction of hypothermic cerebrovascular arrest in neurosurgical operating rooms. The ebb and flow of neurosurgical interest in hypothermia that has since persisted reflect our continuing struggle to achieve the neuroprotective benefits of cooling while minimizing the systemic side effects.

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Ali M. Elhadi, Joseph M. Zabramski, Kaith K. Almefty, George A. C. Mendes, Peter Nakaji, Cameron G. McDougall, Felipe C. Albuquerque, Mark C. Preul and Robert F. Spetzler

OBJECT

Hemorrhagic origin is unidentifiable in 10%–20% of patients presenting with spontaneous subarachnoid hemorrhage (SAH). While the patients in such cases do well clinically, there is a lack of long-term angiographic followup. The authors of the present study evaluated the long-term clinical and angiographic follow-up of a patient cohort with SAH of unknown origin that had been enrolled in the Barrow Ruptured Aneurysm Trial (BRAT).

METHODS

The BRAT database was searched for patients with SAH of unknown origin despite having undergone two or more angiographic studies as well as MRI of the brain and cervical spine. Follow-up was available at 6 months and 1 and 3 years after treatment. Analysis included demographic details, clinical outcome (Glasgow Outcome Scale, modified Rankin Scale [mRS]), and repeat vascular imaging.

RESULTS

Subarachnoid hemorrhage of unknown etiology was identified in 57 (11.9%) of the 472 patients enrolled in the BRAT study between March 2003 and January 2007. The mean age for this group was 51 years, and 40 members (70%) of the group were female. Sixteen of 56 patients (28.6%) required placement of an external ventricular drain for hydrocephalus, and 4 of these subsequently required a ventriculoperitoneal shunt. Delayed cerebral ischemia occurred in 4 patients (7%), leading to stroke in one of them. There were no rebleeding events. Eleven patients were lost to followup, and one patient died of unrelated causes. At the 3-year follow-up, 4 (9.1%) of 44 patients had a poor outcome (mRS > 2), and neurovascular imaging, which was available in 33 patients, was negative.

CONCLUSIONS

Hydrocephalus and delayed cerebral ischemia, while infrequent, do occur in SAH of unknown origin. Long-term neurological outcomes are generally good. A thorough evaluation to rule out an etiology of hemorrhage is necessary; however, imaging beyond 6 weeks from ictus has little utility, and rebleeding is unexpected.

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Adib A. Abla, Timothy Uschold, Mark C. Preul and Joseph M. Zabramski

Object

The aim of this study was to describe a turkey wing model for microvascular anastomosis training and compare it to the previously outlined chicken wing model.

Methods

The authors compared diameter measurements in each of 5 turkey and 5 chicken brachial arteries at 3 equidistant points. Usable vessel length was measured (from joint to joint) in each of the specimens. A survey was created and distributed at a bypass training course to assess the attendees' impressions of various practice models used for bypass.

Results

The turkey wing brachial artery was consistently larger in diameter (p < 0.01) and longer (p < 0.01) than the chicken wing artery and showed less variability in the vessel diameter (1.47 ± 0.14 mm in the turkey vs 1.07 ± 0.25 mm in the chicken). In a survey of 15 bypass course participants, the live rat training model scored highest overall and was ranked as the best model for training; however, the turkey wing model was ranked second best and was consistently scored ahead of the chicken wing and silastic tube training models.

Conclusions

The authors' institutional preference has shifted to the use of a turkey wing artery as the initial model for microanastomosis training. Advantages in terms of vessel size and tissue durability favor this model over the chicken wing as part of a graduated instruction process.

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Sam Safavi-Abbasi, Joseph M. Zabramski, Pushpa Deshmukh, Cassius V. Reis, Nicholas C. Bambakidis, Nicholas Theodore, Neil R. Crawford, Robert F. Spetzler and Mark C. Preul

Object

The authors quantitatively assessed the effects of balloon inflation as a model of tumor compression on the brainstem, cranial nerves, and clivus by measuring the working area, angle of attack, and brain shift associated with the retrosigmoid approach.

Methods

Six silicone-injected cadaveric heads were dissected bilaterally via the retrosigmoid approach. Quantitative data were generated, including key anatomical points on the skull base and brainstem. All parameters were measured before and after inflation of a balloon catheter (inflation volume 4.8 ml, diameter 20 mm) intended to mimic tumor compression.

Results

Balloon inflation significantly shifted (p < 0.001) the brainstem and cranial nerve foramina (mean [± standard deviation] displacement of upper brainstem, 10.2 ± 3.7 mm; trigeminal nerve exit, 6.99 ± 2.38 mm; facial nerve exit, 9.52 ± 4.13 mm; and lower brainstem, 13.63 ± 8.45 mm). The area of exposure at the petroclivus was significantly greater with balloon inflation than without (change, 316.26 ± 166.75 mm2; p < 0.0001). Before and after balloon inflation, there was no significant difference in the angles of attack at the origin of the trigeminal nerve (p > 0.5).

Conclusions

This study adds an experimental component to the emerging field of quantitative neurosurgical anatomy. Balloon inflation can be used to model the effects of a mass lesion. The tumor simulation created “natural” retraction and an opening toward the upper clivus. The findings may be helpful in selecting a surgical approach to increase the working space for resection of certain extraaxial tumors.

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Eberval Gadelha Figueiredo, Joseph M. Zabramski, Pushpa Deshmukh, Neil R. Crawford, Mark C. Preul and Robert F. Spetzler

Object

The management of wide-necked, giant, or unsuccessfully coil-treated basilar apex aneurysms requires a wide exposure, for both working area and linear visualization of the basilar artery (BA). Cranial-based approaches, such as the transcavernous approach, have been proposed to deal with such aneurysms; whether abbreviated forms of this approach might provide similar exposure remains controversial. The authors examine this issue quantitatively.

Methods

Four alcohol-preserved cadaveric heads injected with pigmented silicone were prepared for bilateral dissection. After completing an orbitozygomatic craniotomy, the surgeons worked in a reverse direction, performing the transcavernous approach in five steps: 1) posterior clinoidectomy; 2) cavernous sinus opening; 3) anterior clinoidectomy; 4) cutting of the distal dural ring; and 5) cutting of the proximal dural ring.

Performing the complete transcavernous approach significantly increased the working area and linear exposure of the BA compared with abbreviated forms of the approach (p < 0.05). Opening the roof of the cavernous sinus significantly increased the working area compared with posterior clinoidectomy alone (p = 0.014); however, additional gains in exposure required completing the transcavernous approach. Resection of the anterior clinoid process combined with opening of only the distal dural ring did not significantly increase the working area or linear exposure of the BA.

Conclusions

The complete transcavernous approach significantly increases the working area and linear exposure of the BA compared with the more conservative forms of approach.

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Cassius V. C. Reis, Sam Safavi-Abbasi, Joseph M. Zabramski, Sebastião N. S. Gusmão, Robert F. Spetzler and Mark C. Preul

✓ Almost 50 years of research on moyamoya disease (1957–2006) has led to the development of a variety of surgical and medical options for its management in affected patients. Some of these options have been abandoned, others have served as the basis for the development of better procedures, and many are still in use today. Investigators studying moyamoya disease during this period have concluded that the best treatment is planned after studying each patient's presenting symptoms and angiographic pattern.

The surgical procedures proposed for the treatment of moyamoya disease can be classified into three categories: direct arterial bypasses, indirect arterial bypasses, and other methods. Direct bypass methods that have been proposed are vein grafts and extracranial–intracranial anastomosis (superficial temporal artery–middle cerebral artery [STA–MCA] anastomosis and occipital artery–MCA anastomosis). Indirect techniques that have been proposed are the following: 1) encephaloduroarteriosynangiosis; 2) encephalomyosynangiosis; 3) encephalomyoarteriosynangiosis; 4) multiple cranial bur holes; and 5) transplantation of omentum. Other options such as cervical carotid sympathectomy and superior cervical ganglionectomy have also been proposed. In this paper the authors describe the history of the development of surgical techniques for treating moyamoya disease.