Spine Deformity in Neuromuscular Diseases.
Compiled by the RRTC in Neuromuscular Diseases Staff.
Spine deformity may be scoliosis, kyphosis, or hyperlordosis.
Kyphosis is an exaggerated curve in the cervical upper portion
of the back, and hyperlordosis an exaggerated curve in the lumbar
lower portion of the back. Spine deformity, especially scoliosis,
is linked to the degree and length of progression of weakness
and the loss of ambulation. However, this linkage is not necessarily
a cause and effect relationship. Individuals with amyotrophic
lateral sclerosis, a very rapidly progressive NMD, do not develop
scoliosis (less than 1%) since the progression is so rapid.
Boys with Duchenne muscular dystrophy (DMD) usually develop
scoliosis since the progression of weakness is rapid and loss
of ambulation occurs at an early age. Individuals with spinal
muscular atrophy (SMA) frequently develop scoliosis, but only
if the onset occurred early in life.
As part of one research study at the RRTC, 547 individuals with
ten different NMDs were evaluated. Diseases with the highest
incidence of spine deformity were Friedreich's ataxia (FA; 100%),
infantile onset SMA (78%), DMD (63%), congenital myotonic muscular
dystrophy (MMD; 47%) and childhood onset limb girdle syndrome
(LGS; 44%).
In DMD, all but one of the individuals with spine deformity
had scoliosis. There was a progressive increase in incidence
up to age 20 and 9 years of wheelchair dependency. Thirty-five
percent occurred before age 8. The severity of the curve was
greatest between the ages of 13 and 15 years corresponding closely
with the adolescent growth spurt in boys. There was no relationship
between incidence, convexity of the curve, severity, wheelchair
dependency time, obesity, hip contractures, handedness and onset
age. Spinal (back) braces had only a modes effect on slowing
the progression of the curve, but increased standing with long
leg braces and spinal surgery did. The rate of curve progression
in untreated boys was four degrees per year. Scoliosis had no
effect on mortality or pulmonary (pneumonia, etc.) but a profound
effect on pulmonary functions (vital capacity).
Of the individuals with hereditary spinal cerebellar ataxia
(HSCA) all of those with Friedreich's ataxia had scoliosis as
compared to only 32% if those with other types of HSCA. There
was no relationship to disease duration or years of wheelchair
dependency. Equal numbers with and without scoliosis (40%) had
a history of significant pulmonary complication. While 78% of
the infantile onset individuals with SMA had scoliosis only
8% of those with juvenile and adult SMA had spine deformity.
Like DMD, the incidence and severity of the scoliosis increased
with disease duration and years of wheelchair dependency with
a high incidence of pulmonary complications and decreased pulmonary
function in those with scoliosis.
The overall incidence of spine deformity in the more slowly
progressive NMDs was only 32%. In those with spine deformity
(29% scoliosis), there was no relationship between spine deformity,
disease duration, and length of wheelchair dependency, and most
had mild to moderate scoliosis curves, usually non progressive.
There was, however, a significant association between the number
of pulmonary complications and disease duration in those with
spine deformity who also had significantly lower vital capacities.
Only 13% of the individuals with Becker's muscular dystrophy
had scoliosis and the curves were mild nonprogressive. While25%
of the individuals with hereditary motor sensory neuropathy
(HMSN-CMT) had spine deformity, only 15% had scoliosis alone.
The others had scoliosis with Schuermann's kyphosis (another
hereditary disease). Thirty-five percent of the persons with
facioscapulohumeral dystrophy had spine deformity, but only
15% had scoliosis alone. The others had hyperlordosis and scoliosis
or hyperlordosis alone. The hyperlordosis was more disabling
than the scoliosis. Spine deformity in the congenital myopathies
occurred primarily in the individuals with congenital muscular
dystrophy (36%). The incidence of spine deformity in limb girdle
syndrome also depended on the type. Individuals with the childhood
onset type had a 44% incidence while those with the late onset
and pelvofemoral types had only a 6% incidence. There was also
a marked difference in the incidence of spine deformity between
congenital MMD and MMD. Forty-seven percent of the former had
scoliosis as compared to 15% in the latter.
Spine deformity in the form of scoliosis, kyphoscoliosis and
lordosis represents a common complication in individuals with
NMDs, especially those who are wheelchair-dependent. These changes
are directly or indirectly associated with the extent and severity
of the disease and the supporting musculature of the spinal
column. Spinal collapse is affected by progression of the disease,
changes in posture, changes in seating support, growth and the
use of spinal supporting braces. It can result in decreased
pulmonary function and increased respiratory disease, deterioration
of comfort and activities of daily living, and decreased quality
of life. Early recognition of spine deformity is important,
and a treatment plan instituted as soon as possible. Treatment
consists of prolonged standing/ambulation, wheelchair seating
modifications, back braces and spinal surgery.
From RRTC Newsletter, January 1993.
| 
