Omental Transposition Surgery for Mild Alzheimer's Disease

Overview

This study is a prospective, single arm, non-randomized, interventional study to evaluate the safety and effectiveness of Omental transposition (OT) in subjects with early stage AD. Within-subjects (repeated-measures) design will be utilized to compare follow-up outcomes to baseline. The following assessments will be performed at baseline, then at 1, 3, 6, 12, and 24 months following surgery: * Montreal Cognitive Assessment (MoCA) * Alzheimer's Disease Assessment Scale-Cognition (ADAS-Cog) * General Practitioner Assessment of Cognition (GPCOG) * Eight-item Informant Interview to Differentiate Aging and Dementia (AD8) Subjects who have early stage AD confirmed by a neuropsychological test (MoCA) and who are healthy enough to undergo surgery. The experimental procedure to be performed is omental transposition (OT) surgery. It will be performed as a laparoscopic or open procedure for omental lengthening and an open procedure for brain access, with a general surgeon performing the omental lengthening/tunneling and a neurosurgeon performing brain access/brain biopsy/omental placement on brain. Up to twenty-five (25) subjects, with the first 5 subjects being part of a learning curve group and the next 20 subjects being part of the experimental group. The duration of each subject's participation will be approximately 25 months from screening through the 24 month follow-up visit.

The experimental procedure to be performed is omental transposition surgery, during which a general surgeon and a neurosurgeon work as a team to transpose a pedicle omental graft to the surface of the brain. The general surgeon is responsible for performing a laparotomy/laparoscopy, elongating the omentum into a long pedicle and developing an extensive subcutaneous tunnel up the chest and neck to the head. The neurosurgeon is responsible for performing the craniotomy and securing the omentum on the brain. Creating an intact omental pedicled flap requires the services of a general surgeon and neurosurgeon. The first step in the operation is to obtain access to the abdominal cavity laparoscopically using four 5cm trocars, or via laparotomy through an upper midline incision. The omentum is then removed from the transverse colon, after which it is separated from its proximal and central attachments to the stomach. The omentum detachments are made directly on the greater curvature of the stomach, leaving the gastroepiploic arteries and veins within the still-connected omentum apron. Final separation of the omentum from the proximal portion of the stomach is done by dividing the left gastroepiploic vessels, which at the highest proximal level on the stomach become the short gastric vessels. The vascular connections to and from the omentum are now maintained solely from the right gastric and right gastroepiploic vessels. In order for the omental pedicle graft to reach the brain without tension, further surgical tailoring of the omentum is carried out, with care being taken to ensure the preservation of a major omental artery and vein. After the omentum has been lengthened to an appropriate extent to reach the head, several small (3- to 4-inch) transverse incisions are made on the chest wall slightly lateral to the midline, with the side of the midline to make the transverse incisions depending on which cerebral hemisphere the omentum is to be placed. These transverse incisions are connected subcutaneously, thus creating a tunnel that begins at the upper pole of the midline abdominal incision and travels subcutaneously, up the chest wall and neck to behind the ear. Although the subcutaneous tissue behind the ear is extremely dense, it is essential that the tunnel at this location be at least 2-3 finger lengths in width so that there is no constriction on the omentum in this particular area within the tunnel. As the omentum in the tunnel passes behind the ear, it goes beneath the base of the scalp flap that had been previously dissected in making the initial craniotomy incision. The neurosurgery portion of the operation involves removal of a single piece of bone over the temporal-frontal area, opening the dura mater, followed by the removal of patches of arachnoid membrane, with care being taken to avoid blood vessels on the surface of the brain. At this point in the operation, the omentum is laid directly upon the parietal-temporal-frontal area, after which the dura mater is sutured to the omentum. It is not necessary that the edges of the omentum be applied to the cut edges of the dura since the omentum can be tucked under the edges of the dura for greater coverage of the brain. The edges of the dura are then sewn to the top surface of the omentum using absorbable sutures and the craniotomy is closed.