Selective
DORSAL RHIZOTOMY
by Rick Abbott, M.D.
Selective dorsal Rhizotomy
(SDR, also called functional dorsal rhizotomy)
is a neurosurgical technique to treat spasticity, especially in
children with cerebral palsy. This procedure which evolved from
work in the late nineteenth century, is based on the assumption
that spasticity results from loss of the moderating influences
of nerves, from the brain on the spinal cord's many reflex
circuits, SDR can permanently relieve spasticity in the legs.
With therapy, walking may be improved; sometimes, spasticity
affecting the arms may also improve, as many abilities for
activities of daily living (ADL's)
Evaluation
SDR is
"selective" because the surgeon selects appropriate rootlets to
be cut and because not all individuals with spasticity should
undergo this procedure. There are two broad categories of
candidates;
-
individuals, limited in performing actives by their
spasticity, with sufficient underlying voluntary power to
maintain and eventually improve their abilities once
spasticity is alleviated. They also need to be able to
understand the importance of actively participating in
therapy;
-
individuals, unable to walk, for whom spasticity interferes
with sitting, bathing, positioning and general care taking.
Individuals with spasticity are also considered for SDR if
their spasticity is so severe that it causes painful hip
dislocation and bony deformities that cannot be repaired via
orthopedic surgery. However, if an individual needs his/her
spasticity to stand or walk, then treatment may impair
function and not be advisable.
Surgery
During SDR
surgery, the sensory nerve roots, which run from the spastic leg
muscles to the spinal cord, are separated from the motor nerve
roots and stimulated electrically. Leg muscles are observed for
contraction by a a clinician using an EMG
( an electrical device which records
muscle contraction). Individual
roots that cause abnormal contraction are separated into their
component rootlets which, in turn, are stimulated. Abnormally
responding rootlets are cut.
In most cases, the
majority of rootlets respond abnormally. The neurosurgeon
decides how many may be cut without creating a sensory deficit.
The procedure takes four to eight hours or longer.
Because of some
children's vulnerability to muscle spasms, the pain and
discomfort associated with SDR can be severe for two to three
days. Accordingly, high doses of narcotics may be delivered
directly into the wound via the catheters left in the surgical
site.
For three or four
days after the operation, the child is confined to bed, lying on
his or her stomach. The child will feel sleepy and weak,
especially in the legs. After about 10 days, the stitches are
removed and the child can be transported in a wheelchair.
For a child with
potential to improve functional abilities, intensive therapy
begins while the child is still in bed.
After about a
month, the child can return to regular activities; intensive
therapy (four or more hours each
week) continues. After three
months, therapy is required two to three hours each week.
Whenever possible, physical therapy is supplemented by parental
help in stretching and strengthening activities.
After SDR, children
soon discover that their bodies are operating under different
rules. The difference is similar to the way an automobile
handles after a driver discovers she or he has been driving with
the brake engaged and releases it. Therapy is essential in the
postoperative period because the child needs to "re-learn" body
control.
During the first six
to nine months following SDR, significant improvement is seen.
Some children continue to improve for several years.
SDR usually decreases
spasticity; however, functional abilities do not always improve.
Side effects and complications
Side effects and
complications during the procedure can include: asthma attacks-
especially in children with a history of asthma, bronchitis or
recent upper respiratory tract infection- and vomiting into the
lungs.
Side effects
and complications after the procedure can include: temporary
trunk weakness; an increase in muscle tone associated with
severe pain at the site of the incision and spasms lasting as
long as 48 hrs; temporary inability to urinate
(sometimes requiring bladder
catheterization); temporary
( one to four weeks)
"pins and needles" sensation in the legs,
and small areas of permanent numbness in the legs.
Lon-term
complications are also being recognized. Hip dislocations have
occurred in a small number of individuals-typically in those who
were unable to walk prior to surgery and who had a lot of hip
and pelvic instability due to weakness of hip musculature.
(Hip dislocations also occur in individuals who do not undergo
rhizotomies.)
Many children have experience loss of available range of motion
(ROM)
in their knee and ankle joins after initial improvement, even
though their improved tone remains. This deterioration in ROM
may reflect inadequate stretching of the muscle groups
(resulting in contractures)
during the growth spurt. This complication can mean the need for
ongoing therapy.
SDR does not
replace the need for physical therapy; it may actually increase
it to the degree that the child's potential abilities increase.
Some have been concerned about the possibility of scoliosis
(spine curvature)
after SDR. However, there have been no reports that the risk of
scoliosis has increased using current procedures.
Long-term results
Children with
various degrees of leg spasticity
(able to walk, able to crawl, unable to walk or crawl)
have significant improvement in the tone of every muscle tested.
Also, preoperative functional goals set by the clinical team are
met more than 80 percent of the time. However, it is becoming
apparent that SDR is not a procedure guaranteed to prevent the
need for further surgery. Some may eventually require hip
surgery due to significant hip dislocation. Some may require
tendon surgery to increase limited range in a joint.
credit for this article goes to
Rick Abbott, M.D. and Exceptional parent Magazine
