[Microsurgical treatment of complicated tethered cord resulting from mixed lipoma in a 12-year-old patient: a case report].

A 12-year-old boy was admitted for complaint of progressive urination disorder for over 2 years. Physical examination found dysesthesia in the perineal region and disappearance of anal reflex with anal relaxation and a spinal cleft in the sacrococcygeal region. Lumbosacral magnetic resonance imaging MRI showed a low-set of the spinal cord, tethered cord, spina bifida of sacral vertebrae, and meningocele combined with lipoma inside and outside of the spinal canal. Ultrasonography displayed a significantly increased residual urine volume. The diagnosis of tethered-cord syndrome resulting from mixed lipoma was thus established. During the microsurgery, the adhesions between the spinal cord, coccygeal nerve and lipoma were released with a laser scalpel, and the lipoma inside and outside of the spinal canal was excised, after which the dural defect was repaired. The patient recovered smoothly, and the urinary function was normal at the follow-up 6 months after the surgery. Spinal cord lipoma can be classified into 2 types based on the integrity of the dura mater, and in this case, a combined dural defect was found. A definite diagnosis can be derived from the clinical manifestations and MRI findings. Microsurgery remains the currently only effective treatment, and a favorable prognosis can be expected after an early surgical intervention, especially before the functional lesion of the spinal cord. The integrity of the local dura mater considerably affects the outcome of the treatment, and dural defect often leads to surgical difficulty and poor results. The key to a successful operation lies in a full release of the adhesion and avoidance of injury to the conus medullaris and cauda equina. A reoperation in case of recurrence should be carefully evaluated for its benefits.