Chiari malformation and syringomyelia
Investigating the natural history and predicting outcomes
- If a child has a Chiari malformation (CM) and is asymptomatic, will symptoms develop later, and if so, over what time period?
- Are there imaging characteristics that can predict symptom onset and surgical outcomes?
- What is the time course for recovery following surgery for syringomyelia?
- Do symptomatic patients have other brainstem abnormalities?
Nicholas M. Wetjen, M.D., a pediatric neurosurgeon at Mayo Clinic in Minnesota, reels off these and other unanswered questions as he explains the need for better understanding of the pathogenesis, natural history and clinical models of CM and syringomyelia.
CM is a congenital disorder in which the cerebellar tonsils protrude through the foramen magnum into the spinal cord. The disorder may reflect inadequate room in the posterior fossa to contain its structures. CM type I (CM-I) can occur in children and adults and may or may not be symptomatic. CM type II (CM-II) occurs only in patients with spina bifida defects.
The leading cause of syringomyelia, CM also can occur without a syringomyelic cavity. In syringomyelia, a syrinx or cyst accumulates cerebrospinal fluid within the spinal cord, causing expansion of the spinal cord. The symptoms of syringomyelia tend to be more severe than those of CM-I.
Most-common symptoms associated with Chiari malformation and syringomyelia
- Headache often precipitated by Valsalva maneuvers
- Vocal quality changes
- Swallowing problems
- Sleep disturbance
- Balance problems and dizziness
- Sensory loss or exaggerated response to pain, temperature or position
- Limb weakness and atrophy (particularly hands and arms)
- Pain in thoracic spine area and shoulder joints; burning pain in arms and trunk
- Sphincter problems
- Autonomic symptoms
As Dr. Wetjen notes, MRI has revolutionized CM diagnosis, leading to the detection of previously unrecognized or misdiagnosed occurrences of CM-I. It is present in as many as 2 percent of the general population, although only a small proportion of those with CM-I are symptomatic. Dr. Wetjen sees approximately 180 cases of CM a year, in patients ranging from newborn to 18 years of age, of whom approximately one-third are treated surgically.
The success of surgical reconstruction depends in large measure on early detection. Diagnosis of CM at Mayo Clinic is conducted by a multidisciplinary team that may include specialists in neurology, otolaryngology, orthopedics, sleep disorders and speech pathology.
"For example," Dr. Wetjen says, "a swallow study can detect problems that children are too young to explain and that may have gone undetected by parents." Specialists in sports medicine may also be called on to evaluate the risks of specific athletic activities."
Identification through MRI, patient registry, and review of Mayo's large practice in CM and syringomyelia is providing new opportunities to trace the natural history of these disorders and to predict symptom onset and recovery from surgical intervention.
"There are numerous reports in the literature about diagnosis and symptom relief from surgery, but we hope to add specificity," says Dr. Wetjen, explaining the series of retrospective and prospective studies that he and his colleagues are conducting. Their investigations are aimed at:
- Increased precision about the course of symptom resolution after surgery
- Identification of factors that predict both positive and negative outcomes
- A better understanding of brain abnormalities that may be associated with or independent of CM
In addition, Mayo Clinic participates in the Park-Reeves Syringomyelia Research Consortium, a multi-institutional registry that involves more than 30 centers. Through these in-house and collaborative research initiatives, Dr. Wetjen and colleagues hope to provide clinical models of practice that can be replicated at other institutions and improve patient care.