Clinical evaluation on etiology and
surgical outcome in syringomyelia associated with Chiari type I malformation
Imae S
Department of Neurological Surgery, Wakayama Medical
College, Japan.
Etiology of syringomyelia associated with Chiari type I
malformation has been unknown. Moreover, the surgical procedure of foramen
magnum decompression for this type of syringomyelia has not been standardized
yet. No one procedure has been always successful, leading to many alternative
procedures. The purpose of the present study is to elucidate pathway of
cerebrospinal fluid into the syrinx cavity and to find out the best procedure
for this disease. Forty two patients with syringomyelia associated with Chiari
type I malformation, which were diagnosed with magnetic resonance imaging (MRI),
underwent surgical treatment. In all patients, craniocervical junction
anomalies, cervical disc herniation and other spinal diseases were ruled out.
There were 26 men and 16 women, ranging from 6 to 72 (mean: 42.3) years in age.
The size, length and position of upper end of each syrinx
cavity and the degree of the tonsillar herniation were measured on preoperative
T1-weighted image and were compared each other. There were no significant
relationship between the degree of tonsillar herniation and the size, length and
position of syrinx cavity. No case showed that the upper end of syrinx cavity
communicated to the 4th ventricle. The results suggest that the pathway of
cerebrospinal fluid into the the syrinx cavity was not central canal from the
4th ventricle but microcanals in the spinal cord. All patients were carried out
with foramen magnum decompression, which was divided into 4 groups according to
the degree of decompression: 1) tonsillectomy group: 12 patients underwent
subocciptital craniectomy (SOC) with patcy-graft dural plasty using lyophilized
dura mater and tonsillectomy, 2) lysis group: 7 underwent SOC, dural plasty and
microsurgical lysis of arachnoidal trabecula and fibrinoid filament around
herniated tonsil, 3) plasty group: 17 underwent SOC and dural plasty and 4)
dural group: 6 underwent SOC and removal of the outer layer of the dura mater.
The mean follow-up periods were 3.7 years in tonsillectomy group, 3.6 years in
lysis group, 2.3 years in plasty group, 1.8 years in dural group, respectively.
Evaluation of the result following four types of surgical
treatments was performed on clinical symptoms and the volume of syrinx cavity on
sagittal MRI. The ratio in the area of the syrinx and spinal cord on
preoperative and postoperative sagittal MRI were measured. There was no
significant difference among 4 groups on the degree of reduction of syrinx in
the sagittal plane as evaluated on MRI, whereas with regards to improvement of
the clinical symptoms, dural group was significantly worse than the other three
groups. The surgical procedure of dural plasty was clearly less invasive than
those of tonsillectomy and lysis of subarachnoidal trabecula. These results
suggest that we should select duraplasty as a primary surgical procedure for
syringomyelia associated with Chiari type I malformation.
Back to: Wacma
Home or Onsite Information
|
