OBJECTIVE: To determine a solution capable of discerning adipose versus nervous tissue, to aid in surgical separation of the adipose tissue which appears to be visually indistinguishable from nervous tissue in lipomyelomeningoceles (LMMs). METHODS: The following solutes (in normal saline) were investigated, both at 25 and 37 degrees C: beta-carotene, vitamin D, vitamin E, lecithin, hydrogen peroxide, lipase, protease, hyaluronidase, partially purified collagenase, purified collagenase, trypsin, trypsin plus purified collagenase and non-solute-containing saline (control). Each solution was applied to a pediatric lipoma to determine gross effects over a period of approximately 30 min. If a solution appeared to affect the adipose tissue grossly, studies of functional in vivo sensory evoked and spontaneous potentials using that particular solution were conducted upon sheep spinal cord, nerve roots, dura and peripheral nerve. Additionally, histological studies were conducted to determine the effect of that solution upon adipose tissue, spinal cord, myelin, dura and nerve roots. RESULTS: Of all solutions investigated, partially purified collagenase type 1 (T1C; Lot M0M4322, Code CLS-1, Worthington Biochemical Corporation, Lakewood, N.J., USA) at 37 degrees C was the most successful in grossly altering the consistency and appearance of adipose tissue. This change was more apparent over 20-30 min following application of the solution to the adipose tissue. Solutions not containing T1C did not show appreciable results; purified collagenase plus trypsin did not appear comparable or superior to T1C. No significant histological or functional change was noted when comparing the spinal cord, nerve rootlets, myelin, dura or peripheral nerve from the T1C-treated group versus normal (untreated) control groups. CONCLUSION: T1C appears to be a potentially effective solution for application during LMM surgery in the acute setting, and such use of an adjunct solution may significantly aid in the safe surgical resection of LMMs. Pending further research, this technique may be applied for other indications which require discernment or alteration of adipose versus nervous tissue.