Lipomyelomeningocele: Pathology, Treatment, and Outcomes

A Review

Christina E. Sarris, B.S; Krystal L. Tomei, M.D., M.P.H; Peter W. Carmel, M.D; Chirag D. Gandhi, M.D.

Disclosures

Neurosurg Focus. 2012;33(4):e3 

In This Article

Surgical Intervention

Surgical objectives in a lipomyelomeningocele repair include removal of the adipose mass, identification of the defect in the lumbosacral fascia for release of the tether, possible release of the filum terminale, preservation of neural elements, and prevention of retethering of the spinal cord (Fig. 3).[2] The lipomatous component is intimately associated with the neural placode, which will preclude complete resection of the lipomatous component without neurological injury.[51] Lipoma resection may be achieved utilizing cautery, laser, or ultrasonic aspiration. Additionally, if primary repair of the dura cannot be achieved, duraplasty may be warranted. There have been minimal associations between the types of dural substitutes used for duroplasty and their relation to retether of the cord.[47] Many of the studies evaluating efficacy of various dural substitutes in duraplasty for lipomyelomeningocele include surgery for myelomeningocele as well. Lipomyelomeningocele is considered among the complex pathologies prone to secondary tether. A study comparing complex (myelomeningocele, lipomyelomeningocele) to noncomplex (fatty filum, split cord malformation) pathologies demonstrated a higher incidence of retether in complex pathologies with primary dural closure, but no statistical difference in retether with duroplasty.[59] A generous duraplasty, therefore, may in fact be protective against retethering by creation of a larger CSF space around the neural placode.[59] It should be noted that some late complications have been noted with Silastic duraplasty including neomembrane formation, which may predispose the patient to hemorrhage near the operative bed, and low virulence infections.[16]

Figure 3.

Intraoperative rostral (left) and caudal (right) photos demonstrating progression through a lipomyelomeningocele resection. A: Fascial defect (large arrow) with lipoma emerging from the subfascial space to the subcutaneous space. The superficial lipoma component is denoted by the small arrow. B: The superficial lipoma has been resected, demonstrating a clear fascial defect (arrow). C: Further dissection reveals the interface between the lipoma and dura (arrow) as the lipoma emerges into the epidural space. D: Dense adhesion of the lipoma to conus medullaris with sacral nerve roots lying ventral to lipoma.

Timing of surgical intervention has remained a rather controversial topic, with some advocating for intervention prior to presentation of neurological dysfunction, and some advocating for waiting to intervene until evidence of dysfunction exists. In the absence of good natural history data on the rate of neurological deterioration secondary to lipomyelomeningocele, it is unclear how many individuals would remain asymptomatic without intervention. However, attempts to determine the natural history of lipomyelomeningocele through extrapolation from initial presentation in various studies would suggest that the condition in a majority of patients will deteriorate over time.[10,41] Up to 40% of infants will display abnormal neurological, orthopedic, or urological dysfunction around birth.[33,42,55] Much of the literature would suggest that earlier intervention leads to better outcomes, yet it is not clear whether this indicates surgery should always occur prior to the onset of neurological symptoms. Regardless of the timing, the goals of the surgery are consistent: prevent future or further neurological deterioration and preserve or improve current neurological function.

In considering the timing of surgical intervention, one must consider the nuances of surgery as they relate to the morphology of the lipomyelomeningocele. Some correlation exists between the morphology of the malformation and subsequent postoperative deterioration. Cochrane[9] attempted to discern which morphologies of lipomyelomeningocele were most appropriate for early versus late operative intervention, by evaluating outcomes in surgery for transitional lipomyelomeningocele. He considered symmetrical versus asymmetrical malformations: asymmetrical malformations tend to be associated with unilateral deterioration, and symmetrical malformations tend to be associated with bilateral and bladder deterioration. Those patients with symmetrical malformations were less likely than those with asymmetrical malformations to exhibit early postoperative deterioration. As surgery involves identification of the subarachnoid space adjacent to the dorsal roots to facilitate detethering of the lipoma from the dura, this is more easily achieved when symmetry is present. In asymmetrical lesions, the rotation of the lipoma-placode interface makes identification of this safe zone more difficult. The difficulty of the case and likelihood for complication may suggest that those cases more prone to postoperative complications may be more optimal for intervention after the first signs of neurological dysfunction appear.

Because one of the highest morbidities of lipomyelomeningocele is bowel and bladder dysfunction, the appearance of these symptoms, or a change in bowel or bladder dysfunction, should prompt urgent surgical intervention. Longer times to surgery have been associated with worse outcomes.[18] Additionally, urological dysfunction appears to be more reversible in a younger population, namely infants.[3] However, the risk of a major urological problem after surgery such as frequent urinary tract infections, hydronephrosis, need for clean intermittent catheterization, or vesicoureteral reflux appears to be higher in those patients with lipomyelomeningocele as opposed to patients with other closed spinal dysraphisms, and would suggest that a somewhat conservative approach may be indicated in completely asymptomatic patients.[43] Despite the favorable outcomes for early surgery in some series, one must consider both the risk of conservative management and risk of surgery in planning the timing for intervention. From the standpoint of patients who complain primarily of motor or sensory deficits, recovery of motor and sensory deficits occurs more frequently than recovery of normal bowel and bladder function.[34]

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