Syrinx like formations as a rare feature of spinal cord involvement in multiple sclerosis
Introduction: Syrinx formations within the spinal cord (SC) occur most commonly in association with congenital-idiopathic diseases or aquired pathology (post-traumatic, neoplasm, inflammatory arachnoiditis). Symptomatic syringomyelia usually causes the clincal picture of dissociated sensory loss at the level of the cord pathology and may require surgical intervention. We report syrinx like formations in the spinal cord in a large cohort of MS patients who underwent 2 brain and SC MRI examinations 1 year apart.
Methods: Standardised brain and SC MRI of 202 MS patients (140 w, 62m, 24–74 years old, EDSS 0–7.0) with different MS subtypes (CIS, RRMS, SPMS and PPMS) was analysed as part of a genetic study in order to characterise them morphologically and in regard to subclinical disease activity. SC MRI included images in the sagittal and transverse plane of the whole cord employing multi-array-coils and parallel imaging technology.
Results: SC MRI demonstrated the typical sequelae of inflammatory-demyelinating disease: focal lesions, diffuse abnormalities and the combination of both, furthermore focal and generalised atrophy was seen. In 7/202 patients (3.5%) syrinx like formations were identified. All syrinx like formations presented as a non-communicating, isolated dilation of the central canal with CSF signal intensity in sagittal and transverse planes. There was a slight enlarging effect on the cord at the level of the syrinx. The size varied from 2.5–17cm in length and 15–50mm in diameter. In 7/7 patients there were concomitant typical SC MS lesions. Lesions could be close to the syrinx, above or below the cavitation, but there was no obvious pattern of immediately adjacent lesions. Five patients showed slight degenerative changes of the vertebral column, but none causing cord compression. One year F/u MRI demonstrated in all cases unchanged phenomenology of the syrinx. Careful clinical examination showed in none of the cases dissociated sensory loss or suggested a focal functional deficit arising from the syrinx level.
Conclusion/discussion: Noncommunicating oligo/asymptomatic syrinx like formations rarely occur in MS patients. This is different to normal controls in whom syrinx like formations have not been noted in previous studies. In this 202 patient cohort they did not cause obvious clinical symptoms or signs. Displacement of SC tissue by the syrinx was noted without major compressive effect and without a tendency to increase in size over 1 year.