Experimental omento-myelo-synangiosis

Current concepts on the expression of neurotrophins in the greater omentum

The omentum has been utilized in Neurosurgery since the late 1960s. Its overwhelming effects on fibroblast and peripheral nerve growths were soon noticed. However, there was no direct evidence of production of any of the growth factors by the omentum, although substances were shown to be present in the omentum. Three animals were used in the study. After removal of the omentum in one, the tissue was submitted to PCR for BDNF, NT3/4 and NT5. Water was the negative control utilized. There was marked expression of all neurotrophins in the omentum, indicating local production of all those substances. The omentum has, for the first time, demonstrated to produce and not only accumulate neurotrophins. Utilization of this concept may permit transplant or transposition of parts of the omentum into the central nervous system for the management of multiple diseases, including vascular dementia, strokes, Alzheimer's disease or Moya-Moya disease.

Experimental investigation of encephalomyosynangiosis using gyrencephalic brain of the miniature pig: histopathological evaluation of dynamic reconstruction of vessels for functional anastomosis. Laboratory investigation

OBJECT

Encephalomyosynangiosis (EMS) is a surgical treatment for moyamoya disease that is widely used to provide increased intracranial blood flow via revascularization by arterial anastomosis from the external carotid artery. However, the angiogenic mechanism responsible for the revascularization induced by EMS has not been systematically evaluated. In this study the authors investigated the chronological angiogenic changes associated with EMS to clarify the favorable factors and identify revascularization mechanisms by using an experimental internal carotid artery occlusion (ICAO) model in the miniature pig.

METHODS

Fourteen miniature pigs were used, 11 of which underwent ICAO before transcranial surgery for EMS was performed. Animals were allowed to recover for 1 week (4 pigs) or 4 weeks (7 pigs) after EMS. Control group animals were treated in the same way, but without occlusion (3 pigs). Magnetic resonance imaging, angiography, and histological investigation were performed.

RESULTS

One week after EMS, on histological examination of both the ICAO and control groups it was found that the transplanted temporal muscle had adhered to the arachnoid via a granulation zone, which was enriched with immune cells such as macrophages associated with the angiogenic process. Four weeks after EMS, angiography and histological examination of the ICAO group showed patent anastomoses between the external carotid artery and the cortical arteries without any detectable boundary between the temporal muscle and the cerebral cortex. In contrast, histological examination of the control group found scar tissue between the cerebral cortex and temporal muscle.

CONCLUSIONS

The initial step for formation of anastomoses resembles the process of wound healing associated with repair processes such as active proliferation of macrophages and angiogenesis within the new connective tissue. Functional revascularization requires a suitable environment (such as tissue containing vascular beds) and stimulus (such as ischemia) to induce vascular expansion.

Prospective study of omental transposition in patients with chronic spinal injury

OBJECTIVES

This prospective study was designed to assess the effects of omental transposition in patients with a chronic spinal injury.

METHODS

Neurological status was established to be stable and multiple baseline across patient studies were done preoperatively and repeated postoperatively. Assessments included activities of daily living (ADL), functional ability, degree of spasticity, motor power, sensation, pain perception, urodynamic studies, electromyography, sensory evoked potentials (SEPs), and infrared thermography to measure peripheral and general skin vascular responses. Each patient had MRI. Assessments were done at 3, 6, and 12 months after omental transposition in 17 patients.

RESULTS

The detailed assessments failed to show significant improvement, although some patients showed minor objective and subjective change in some categories. Neurological deterioration occurred in one patient. There were 20 surgical complications including urinary tract infection, deep vein thrombosis, wound infection, and incisional hernia.

CONCLUSIONS

Omental transposition has not been shown to improve neurological function in 17 patients with chronic spinal cord injury, and continued use of this operation in this situation is not supported by this study. Further advances in spinal cord repair may utilise the pedicled omental graft to provide an alternative vascular supply, but its current use should be limited to experimental models.