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OMENTAL PROCEDURES

Laurance Johnston, Ph.D.

Sponsor: Institute of Spinal Cord Injury, Iceland

 

 

1) Omental Transposition

2) Omental Transplantation

1) Omental Transposition: Dr. Harry Goldsmith (Nevada, USA) pioneered the development of omental transposition procedures for various central nervous system disorders. His work has stimulated many others who have now treated thousands of patients for SCI and other neurological disorders, such as stroke, cerebral palsy, Alzheimer’s disease, and Parkinson’s disease. The procedure’s acceptance has grown in other parts of the world, such as in China where many individuals have had function-restoring omental surgery.

Physiology: The omentum is a highly vascular, fatty tissue approximately 14-inches long and 10-inches wide that hangs like an apron over the intestines and lower abdomen area. Although the omentum has been viewed as an inert tissue bereft of significant biological function, scientists are now discovering that it is an intriguing, physiologically dynamic tissue with a considerable body of research that supports its therapeutic potential (see specifically, Agner et al, Neurological Research, January, 2001 and The Omentum Application to Brain and Spinal Cord, edited H.S. Goldsmith, Forefront Publishing, 2000):

·        Blood supply: The omentum contains angiogenic factors that stimulate the growth of new blood vessels into whatever tissue it is surgically placed next to, including the brain and spinal cord.

·        Lymphatic System: The omentum is rich in lymphatic vessels and tissue that are critical in removing metabolic waste and excess fluid, destroying toxic substances, and fighting disease.

·        Immune System: Omental areas called “milky spots” are capable of generating specialized immune cells that facilitate healing. For example, some believe that the migration of omental immune cells can help repair injured spinal cords.

·        Edema Absorption: The omentum’s lymphatic system has an enormous capacity to absorb edema fluid, including that associated with spinal cord swelling.

·        Source of Biological Material: The omentum is a rich source of biological material that enhance tissue growth, including angiogenic factors, key neurotransmitters, nerve growth factors, and agents involved in inflammatory and immune processes.

·        Stem Cells: Evidence suggests that omental tissue contains stem cells - omnipotent master cells that can differentiate into a variety of cell types. For example, Dr. Ignacio Garcia Gomez (Madrid, Spain) and colleagues demonstrated the presence of stem cells in the human omentum (Neurological Research, 27, December 2005). These cells were shown to synthesize key growth factors that promote vascularization when transplanted.

Transposition Surgery: In a six-hour operation, surgeons cut into the abdominal cavity to access the omentum, which is then gently separated from the colon and the stomach in a way that maintains blood and lymphatic circulation. It is then surgically tailored to create a pedicle – a piece of connected tissue of sufficient length with intact circulation to reach the injury site, like a square handkerchief would be cut to make a long necktie. The omental pedicle is then tunneled underneath the skin, placed over the exposed cord, and sutured to the cut edges of the dural membrane surrounding the cord.

Because creating the omental pedicle can be tricky, some surgeons use a substitute procedure, in which a free, unattached piece of omental tissue is surgically placed over the injured cord and connected to a surrounding vascular source. Although blood circulation is maintained, because the graft is separated from the omentum’s lymphatic system, the tissue’s ability to absorb fluid is eliminated.

Goldsmith estimates that about 40% of omental SCI patients have regained some function; Chinese surgeons have reported an even greater improvement rate. 

Criticism: A 1996 study (Clifton, et al, Spinal Cord, 34, 1996) appeared to provide the evidence to dismiss omental transposition as a viable SCI treatment. In this study, 11 patients with SCI were examined a year after omental surgery. Results were inconclusive; some subjects improved, and others did not. Because these ambiguous results were associated with side effects, the investigators concluded that there was “no justification for further clinical trials of this procedure.”

However, soon after Goldsmith rebutted this criticism (Spinal Cord, 35, 1997). Specifically, Goldsmith noted that the investigators had used two different surgical procedures, automatically confounding the study. Over half the time, they had used a free omental tissue graft instead of, as stated in their objectives, an attached omental pedicle. By so doing, they eliminated the tissue’s beneficial fluid-absorbing capability.

Furthermore, although the study’s goal was to determine the specific effect of the omentum placed directly on the injured cord, the final analysis included outcomes of several patients whose omental graft was shown not even to be physically attached to the cord or had been surgically removed before analysis. In other words, they had factored in results that were not applicable to the stated study objectives, and, hence, significantly skewed the reported results.

Collagen/Omentum Case Study: In 2005, Goldsmith and colleagues reported the use of an omental/collagen bridge to help restore function in Andrea a young German woman who became paraplegic 3½ years earlier from a skiing accident (Neurological Research 27, 2005). Andrea’s post-injury MRI indicated a near total spinal cord transection at the thoracic T6-7 level. Three and half years after injury, Andrea underwent surgery in which the scar tissue that now filled the 4-cm gap in her cord was replaced with an omental-collagen bridge. After removal of the scar tissue, 4-5 cc of collagen, a reverse polymer that hardens at body temperature, was delivered into this gap, and after hardening, an omental pedical was sutured over the collagen bridge.

Several years after the surgery, Andrea started an aggressive physical rehabilitation at the Neuro Institute (Phoenix, AZ) managed by Arnie Fonseca, a co-author. Since her surgery, she has regained considerable function below the injury level, including some ambulatory ability.

The article includes a series of MRIs taken immediately after injury and after construction of the omental-collagen bridge; and 1, 2, 3, 4, 5, and 6 years after surgery.  These time-sequential MRIs demonstrate ongoing development of axonal structure connecting the proximal and distal spinal cord segments.

Proposed Procedures for Acute SCI:  In 2007, Goldsmith proposed that the acute injury phase may be the most optimal time to place the omental pedical over the injury site (Neurological Research, 29, 2007).  As noted above, the omentum’s huge capacity to absorb fluid could potentially reduce neurological damage associated with spinal-cord swelling at the time of acute injury. The fluid that accumulates at the injured cord promotes scar development, resulting in the constriction of nearby capillaries and, in turn, healing-inhibiting ischemia (i.e., compromised blood flow).  Specifically, the omentum’s absorption of edema fluid would lower the levels of fibrinogen, the protein from which blood-clot-forming fibrin is generated, resulting in less scar-tissue formation.  Although the spinal cord is often surgically decompressed soon after injury to remove impinging tissue or bone fragments, this procedure does not necessarily release the swelling-related pressure underneath the spinal-cord membrane. At the time of surgical decompression, Goldsmith suggests that a pressure-releasing incision be made in this membrane followed by the placement of a fluid-absorbing omental pedical over the now-exposed cord.  

Dr. Himanshu Bansal (India) and colleagues have incorporated Goldsmith’s omental transposition ideas into their growing therapeutical armamentarium for acute SCI. Specifically, they have placed a fluid-absorbing omental pedical over the exposed cord of several individuals with thoracic injuries. Because the cord was lacerated in these injuries, decompression was not required as is often the case with contusion injuries.

Although recognizing it is difficult to assess treatment-related improvements in the acute-injury phase, Bansal will attempt to get insights on effectiveness by comparing treated patients with untreated individuals with comparable injuries. He will also carry out various follow-up tests six months afterwards, including neurological assessments, evaluation of injury-site MRI’s, and electrophysiological measurements of nerve conduction.

Bansal intends to perform these omental transposition procedures on more patients in the future. The timing of his procedures will depend upon the nature of the injury as determined by MRI assessments: 1) pure contusion, 2) less than 50% of the cord lacerated, 3) more than 50% but not all of the cord lacerated, and 4) complete transection of the cord.

For example, in the case of pure contusion injuries, he intends to carry out decompression and transpose the omentum immediately after injury; with lacerative injuries, he will wait several weeks.  

2) Omental Transplantation: Many others have used omental transplantation, not transposition, including Dr. Carl Kao and Dr. Hernando Rafael (Mexico). As reported at the 2001 WHO-sponsored conference held in Reykjavik, Iceland, Rafael grafts an unattached piece of omental tissue over the injured cord and connects it to a surrounding vascular source.  At the time of the conference, he had treated 232 patients with traumatic SCI with the procedure. He claimed that 43 percent have neurologically improved, including 43 who are walking with or without the use of orthopedic devices. Somewhat similar omental transplantation procedures were reported by Moscow’s Dr. Georgie Stepanov.

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