Indications
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Tethered cord on magnetic resonance imaging (MRI) (spinal cord adhesions, low conus medullaris, thickened fatty filum, dural sinus, lipomyelomeningocele [LMMC], split cord malformation) with progressive clinical deteriorating symptoms such as pain, sensory impairment, weakness, spasticity, urinary dysfunction, foot deformity, and scoliosis that can be correlated with the spinal cord anomaly.
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MRI diagnosis of a dermal sinus and existence of cutaneous dimpling close to the midline region associated with cerebrospinal fluid (CSF) leak or recurrent meningitis caused by atypical bacteria or both.
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MRI diagnosis without or with minor neurologic symptoms as prophylactic surgery to prevent progressive neurologic deterioration at an early stage of life, considering physical stability with a sufficient body weight at the least age of 6 months.
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Because no evidence is available to address the necessity or the optimal timing of prophylactic surgery, the individual risk to prevent any morbidity must be carefully weighed to justify surgery.
Contraindications
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Severe coexisting congenital abnormalities (central nervous system, cardiac, renal) leading to instability during surgery or associated with an overall short life expectancy should be treated conservatively.
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A tethered cord that is coincidentally detected in fully grown patients with no associated clinical symptoms needs to be carefully observed in a multidisciplinary manner.
Planning and positioning
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Detailed physical and neurologic examinations should be performed to detect clinical findings such as subcutaneous lipomas, skin tags, hemangiomas, hypertrichosis, dimples, foot deformities, scoliosis, spasticity, and weakness. A multidisciplinary work-up (including clinicians from neurology, neurosurgery, and orthopedics; caretakers; and families) should be done to determine the indication for surgery in complex cases.
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MRI of the head and spine is used to verify any central nervous system abnormalities and to localize the lesion and characterize clearly anatomic conditions of the dysraphic spine, extension of the lipoma, condition of the spinal chord, and possible syringomyelia. X-ray or computed tomography (CT) scan or both may be necessary to characterize any spinal osseous anomalies (e.g., scoliosis, dysraphic conditions, hemivertebrae).
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Intraoperative electrophysiologic monitoring with somatosensory evoked potentials, motor evoked potentials, and motor nerve stimulation provides functional feedback of electrophysiologic integrity of the neural structures and is especially helpful if complex lipomas are involved.
Figure 93-1:
Patient positioning is prone with gel cushions placed under the chest and pelvis enabling free abdominal movement for regular ventilating pressure. The extremities are secured with gel or cotton wool bandages to prevent compression injury. The head is carefully tilted and positioned on a gel donut headrest.
Figure 93-2:
Different congenital conditions of tethered spinal cord that represent an incomplete overview of wide variety of complex spinal malformations. A, Spinal lipoma with lumbar dermal sinus. B, Sacral dermal sinus and intraspinal lipoma with caudal regression syndrome associated with imperforated anus. C, Sacral LMMC. D, Dorsal lumbar lipomyelomeningocele associated with split spinal process malformation. E, Complex lipomyelomeningocele associated with diastematomyelia.
Procedure
