A 4-year-old girl with a history of cerebral palsy and severe spasticity presents for selective dorsal rhizotomy (SDR). She is taking baclofen and tizanidine. History and physical examination are otherwise unremarkable.
Spasticity in children usually is caused by cerebral palsy (CP), traumatic brain injury, or spinal cord injury, and can lead to a significantly decreased quality of life. Nonsurgical treatment consists of physical and occupational therapy and oral spasmolytic drugs; invasive options include injections of botulinum toxin, localized orthopedic procedures, intrathecal baclofen (ITB) pump implantation, and SDR. In spastic CP, there is increased alpha motor neuron activity and spasticity due to cerebral hemispheric damage. The goal of SDR is to decrease the excitation of these alpha motor neurons and thus alleviate spasticity, while preserving motor and sensory function. Unlike ITB, SDR mainly improves spasticity of the lower extremities; it does not significantly improve dystonia. SDR usually involves electrophysiologically guided severing of dorsal rootlets from L2 to S1 or S2. The decision as to which dorsal rootlets to cut can be based on the motor responses to stimulation, clinical history, or a combination of the two.
Many children presenting for SDR will have a history of prematurity and associated neonatal lung disease, so there may be intra- or postoperative respiratory complications. Intravenous access and positioning may be difficult because of spasticity. The patient will need to be placed in the prone position for surgery, with all the attendant potential complications.
Antispasticity drugs such as baclofen should not be discontinued preoperatively, as this may precipitate acute withdrawal.
Carefully position patients prone with appropriate padding.
Avoid muscle relaxants to allow for intraoperative electrical stimulation and electromyogram (a one-time dose of muscle relaxant for intubation is acceptable).
Although children with spastic CP are not at increased risk of succinylcholine-induced hyperkalemia, there may be associated increased muscle spasm and rigidity, so succinylcholine is best avoided.
Volatile anesthetics are a good choice for maintenance of anesthesia, since they do not interfere with electrophysiologic monitoring in SDR. Intraoperative supplementation with narcotics may be useful.
Dorsal rootlet stimulation may cause bradycardia and/or hypotension; this may be transient and self-limited, but it may require treatment with atropine.
Avoid aggressive measures to warm patients undergoing SDR, as there may be increased metabolic heat production from stimulation of the lower extremities.
Avoid ketamine, as it may alter the response to electrical stimulation.
Although patients can usually be extubated at the end of SDR, they require intensive care unit observation, primarily for management of postoperative pain. Patients experience significant pain after SDR, due to both multilevel laminectomies and manipulation of nerve roots. Patients generally require continuous narcotic infusions, supplemented by nonsteroidal anti-inflammatory drugs and benzodiazepines. Postoperative fever is common, and is thought to be caused by atelectasis or chemical meningitis.