The leading theory for the occurrence of the Chiari I malformation is underdevelopment of the posterior fossa: a small (hypoplastic) posterior fossa does not provide enough room for the lower part of the cerebellum, cerebellar tonsils, and brainstem. Treatment by posterior fossa decompression is effective for many.
However, could some cases of CM-I be due to a tethered spinal cord? What about syringomyelia and scoliosis?
In 2005, Dr. Miguel Royo Salvador, Director of the Barcelona Neurological Institute, and associates reported their results following treatment of scoliosis, syringomyelia, and Chiari I malformation by section of the filum terminale. The records of 20 patients treated between April 1993 and July 2003 were reviewed. The patients presented with scoliosis, syringomyelia, the Chiari I malformation, or “a combination of these conditions”.
The position of the conus medullaris was reported in 15 patients:
Level Patients
T12 1
L1 9
L1-L2 1
L2 1
L5-S1 3
Each patient was treated by sectioning (cutting) the filum terminale in the sacrum, with or without opening of the dura.
Outcome
The outcome is summarized as follows:
“...patients with syringomyelia showed an early clinical improvement ofdysaesthesia,thermo-anaesthesia,hypo-aesthesiaand walking difficulties. Rising of the medullary conus was also observed. In patients with scoliosis, back pain improved dramatically and a curve reduction was noticed, although progression of the curve was observed in one case. In patients with Chiari malformation, headache, dysaesthesia andparaparesisdisappeared.”
A review of article’s Table 1 reveals:
Scoliosis: There were 8 patients with only scoliosis. The change in the curve was measured in three patients. It decreased in two (6 degrees, 8 degrees) and increased in one (4 degrees). Outcome in 6 patients ranged from 10-90% improvement. Outcome was not available in two.
Syringomyelia: There were 5 patients with only syringomyelia. Outcome was favorable: 40%, 90%, 95%, 100% improvement in 4 patients respectively. One was lost to follow-up. The syrinx cavity decreased in length and increased in width in 2 patients - an insignificant change - and was unchanged in the others.
Chiari I malformation: There were 4 patients with the Chiari I malformation. Of the two patients with only CM-I, one had “50% clinical improvement” and the other had “100% clinical improvement.” Of the two patients with CM-I, syringomyelia, and scoliosis, one had “40% clinical improvement” and the other was lost to follow-up.
Impressions
While the results suggest a possible new treatment approach, it is important to note the limitations of this pioneering study:
1. As a retrospective study based on review of patient records, some important information is not available.
2. The number of cases for each of these conditions is very small.
3. Change in spinal curve reported in only 3 patients.
4. Outcome information is available in only 3 patients with the Chiari I malformation.
5. The extent of tonsillar herniation in the CM-I patients is not reported.
6. Three patients were lost to follow-up.
Although the study is encouraging, caution is in order. As with any medical advance, the role of sectioning of the filum terminale in patients with scoliosis, syringomyelia, and the Chiari I malformation will depend on whether the results are confirmed by other investigators.
Comments and observations welcome.
Reference
Royo-Salvador MB, Sole-Llenas J, Domenech JM, Gonzalez-Adrio R.
Results of the section of the filum terminale in 20 patients with syringomyelia, scoliosis and Chiari malformation.
Acta Neurochir (Wien). 2005 May;147(5):515-23; discussion 523
Posted by John Oro’, MD
The leading theory for the occurrence of the Chiari I malformation is underdevelopment of the posterior fossa: a small (hypoplastic) posterior fossa does not provide enough room for the lower part of the cerebellum, cerebellar tonsils, and brainstem. Treatment by posterior fossa decompression is effective for many.
However, could some cases of CM-I be due to a tethered spinal cord? What about syringomyelia and scoliosis?
In 2005, Dr. Miguel Royo Salvador, Director of the Barcelona Neurological Institute, and associates reported their results following treatment of scoliosis, syringomyelia, and Chiari I malformation by section of the filum terminale. The records of 20 patients treated between April 1993 and July 2003 were reviewed. The patients presented with scoliosis, syringomyelia, the Chiari I malformation, or “a combination of these conditions”.
The position of the conus medullaris was reported in 15 patients:
Level Patients
T12 1
L1 9
L1-L2 1
L2 1
L5-S1 3
Each patient was treated by sectioning (cutting) the filum terminale in the sacrum, with or without opening of the dura.
Outcome
The outcome is summarized as follows:
“...patients with syringomyelia showed an early clinical improvement ofdysaesthesia,thermo-anaesthesia,hypo-aesthesiaand walking difficulties. Rising of the medullary conus was also observed. In patients with scoliosis, back pain improved dramatically and a curve reduction was noticed, although progression of the curve was observed in one case. In patients with Chiari malformation, headache, dysaesthesia andparaparesisdisappeared.”
A review of article’s Table 1 reveals:
Scoliosis: There were 8 patients with only scoliosis. The change in the curve was measured in three patients. It decreased in two (6 degrees, 8 degrees) and increased in one (4 degrees). Outcome in 6 patients ranged from 10-90% improvement. Outcome was not available in two.
Syringomyelia: There were 5 patients with only syringomyelia. Outcome was favorable: 40%, 90%, 95%, 100% improvement in 4 patients respectively. One was lost to follow-up. The syrinx cavity decreased in length and increased in width in 2 patients - an insignificant change - and was unchanged in the others.
Chiari I malformation: There were 4 patients with the Chiari I malformation. Of the two patients with only CM-I, one had “50% clinical improvement” and the other had “100% clinical improvement.” Of the two patients with CM-I, syringomyelia, and scoliosis, one had “40% clinical improvement” and the other was lost to follow-up.
Impressions
While the results suggest a possible new treatment approach, it is important to note the limitations of this pioneering study:
1. As a retrospective study based on review of patient records, some important information is not available.
2. The number of cases for each of these conditions is very small.
3. Change in spinal curve reported in only 3 patients.
4. Outcome information is available in only 3 patients with the Chiari I malformation.
5. The extent of tonsillar herniation in the CM-I patients is not reported.
6. Three patients were lost to follow-up.
Although the study is encouraging, caution is in order. As with any medical advance, the role of sectioning of the filum terminale in patients with scoliosis, syringomyelia, and the Chiari I malformation will depend on whether the results are confirmed by other investigators.
Comments and observations welcome.
Reference
Royo-Salvador MB, Sole-Llenas J, Domenech JM, Gonzalez-Adrio R.
Results of the section of the filum terminale in 20 patients with syringomyelia, scoliosis and Chiari malformation.
Acta Neurochir (Wien). 2005 May;147(5):515-23; discussion 523
Posted by John Oro’, MD