An 8-year-old boy has a history of urinary incontinence and progressive sensorimotor deficits of the lower extremities. MRI revealed a tethered spinal cord. He presents for neurosurgical release of his tethered cord.
Physical examination shows a sacral dimple.
Patients with VACTERL syndrome (vascular abnormalities, anal atresia, cardiac defects, tracheoesophageal fistula, renal abnormalities, and limb defects) may have a tethered cord. However, most patients with a tethered cord, whether presenting as toddlers or as school-age children, are otherwise healthy.
Although a sacral dimple is often the reason for obtaining a spine MRI, sacral dimples are usually not associated with cord abnormalities. However, lumbar skin lesions such as hair tufts, fatty pads, or dimples are often manifestations of spinal abnormalities such as lipomeningocele or dermal sinus tracts, which may cause a tethered spinal cord.
Tethered cord release is performed in the prone position with neural monitoring of lower extremity motor and sensory responses and monitoring of the rectal sphincter innervation. Therefore, the anesthetic induction may take place with the patient supine on a stretcher. After endotracheal intubation, Foley catheter placement, and electrode placement for neuromonitoring, the patient is turned prone. Muscle relaxant may be used prior to endotracheal intubation but should be avoided thereafter to allow motor response testing. The anesthetic should be tailored to allow evoked response recordings by keeping the concentration of potent inhaled agents low and using continuous infusions of propofol and remifentanil.
An arterial line is often placed, particularly if laminectomy will be performed at several levels, although blood transfusion is rarely required even in these cases. Surgery may last for 4-6 hours, particularly in older children. One or two intravenous lines should be placed. A bladder catheter should be placed.
The prone position requires special attention to head, chest, and pelvis support. After the endotracheal tube, orogastric tube, esophageal temperature probe, bladder catheter, and anterior electrodes for evoked potential monitoring are placed, the patient is turned to the prone position. The head may be turned to the side or supported in the midline. The endotracheal tube should remain visible, and the eyes, nose, ears, and mouth should be checked to avoid pressure injury. Support of the upper chest and pelvis can be obtained with 2 bolsters or rolls alongside the trunk or a transverse chest roll and a larger roll under the hips. The abdominal wall should be free to expand without pressure during inspiration, which allows normal ventilator pressures and avoids increased pressure in epidural veins that might increase blood loss. Genitalia must be free from pressure. Arms will be positioned with elbows flexed and hands near the head. Posterior and anal electrodes will be placed prior to draping the patient for surgery.