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Selective Dorsal Rhizotomy

Introduction

Selective Dorsal Rhizotomy involves sectioning (cutting) of some of the sensory nerve fibers that come from the muscles and enter the spinal cord. Two groups of nerve roots leave the spinal cord and lie in the spinal canal. The ventral spinal roots send information to the muscle; the dorsal spinal roots transmit sensation from the muscle to the spinal cord.

At the time of the operation, the neurosurgeon divides each of the dorsal roots into 3-5 rootlets and stimulates each rootlet electrically. By examining electromyography (EMG) responses from muscles in the lower extremities, the surgical team identifies the rootlets that cause spasticity. The abnormal rootlets are selectively cut; leaving the normal rootlets intact. This reduces messages from the muscle, resulting in a better balance of activities of nerve cells in the spinal cord, and thus reduces spasticity.

Procedure

Neurosurgeons typically perform SDR after removing the lamina from 5-7 vertebrae. SDR begins with a 1- to 2-inch incision along the center of the lower back just above the waist. The spinous processes and a portion of the lamina are removed to expose the spinal cord and spinal nerves. Ultrasound and an x-ray locate the tip of the spinal cord, where there is a natural separation between sensory and motor nerves. A rubber pad is placed to separate the motor from the sensory nerves. The sensory nerve roots that will be tested and cut are placed on top of the pad and the motor nerves beneath the pad, away from the operative field.

After the sensory nerves are exposed, each sensory nerve root is divided into 3-5 rootlets. Each rootlet is tested with EMG, which records electrical patterns in muscles. Rootlets are ranked from 1 (mild) to 4 (severe) for spasticity. The severely abnormal rootlets are cut. This technique is repeated for rootlets between spinal nerves L2 and S2. Half of the L1 dorsal root fibers are cut without EMG testing.

When testing and cutting are complete, the dura mater is closed, and fentanyl is given to bathe the sensory nerves directly. The other layers of tissue, muscle, fascia, and subcutaneous tissue are sewn. The skin is closed with glue. There are no stitches to be removed from the back. Surgery takes approximately 4-5 hours. The patient goes to the recovery room for 1-2 hours before being transferred to the intensive care unit overnight.

A right Candidate for Dorsal Rhizotomy

Inclusion criteria

Pediatric:

  • At least 2 years of age
  • Diagnosis of spastic diplegia mostly but a few children with spastic quadriplegia or spastic hemiplegia
  • Independent mobility for example, crawling or walking with or without an assistive device
  • On MRI examination no severe damage to the basal ganglia

Adults:

  • Diagnosis of spastic diplegia
  • Currently ambulates independently without assistive device
  • No or mild fixed deformities
  • Patients who show motivation to attend intensive physical therapy and perform home exercise program

A good candidate will have

  1. Good muscle strength in the legs and trunk.
  2. Evidence of adequate motor control.
  3. History of delayed motor development.
  4. Motivation and ability to cooperate in therapy.

Exclusion criteria

Children with CP who possess some of the following conditions would not be candidates for the SDR surgery. They include:

  • Children who have suffered meningitis, congenital brain infection, congenital hydrocephalus unrelated to premature birth, head trauma, or familial disease
  • Children who have mixed CP with predominant rigidity or dystonia, significant Athetosis or ataxia.
  • Children who have severe scoliosis.
  • Children who will not make functional gains after surgery

Possible Complications

Paralysis of the legs and bladder, impotence, and sensory loss are the most serious complications. Wound infection and meningitis are also possible, but they are usually controlled with antibiotics. Leakage of the spinal fluid through the wound is another risk.

Abnormal sensitivity of the skin on the feet and legs is relatively common after SDR, but usually resolves within 6 weeks. There is no way to prevent the abnormal sensitivity in the feet. Transient change in bladder control may occur, but this also resolves within a few weeks.

Pre-operative Assessment

The therapy assessment focuses specifically on the following areas:

  • Developmental history
  • Spasticity
  • Strength
  • Motor Control
  • Developmental Functions
  • Range of Motion
  • Balance
  • Gait

Possibility of Orthopedic Surgery after SDR.

Any orthopedic surgery can be done after SDR if there is need in the future.

Cost factor and Hospital stay:

The cost of the procedure is same as any other spinal surgical procedure and the child stays in the hospital for 7-15 days altogether. During the hospital stay the child gets regular specialized therapy. After one week or so the child is discharged from the hospital and a home programme is given to the parents to carry out at home