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Intramedullary migration of spinal cord lipoma
Spinal cord lipomas may grow with changes in body fat, and can produce neurological manifestations due to nervous tissue compression or cord tethering. It is very unusual for the tumour to migrate from one part of the cord to another, thus to cause neurological symptoms at the migrated level. This, however, is a report on such a case. To the best of our knowledge, this has not previously been described in the literature.
A 45 year old man presented to a different neuroscience centre with a history of deformity of the right foot since childhood. In his 20s, he developed numbness of the right foot, back pain, right sciatica, and a degree of urgency of micturition and of constipation. In 1998, he developed intermittent intercostal pain and was found to have reduced sensation in the left T4 to T12 region. In October 1998, an MRI scan of the spine showed a low lying tethered cord at L3 with a terminal lipoma of variegated appearance. There was a lipomatous lesion extending cranially to the T10 vertebral level. The lipomatous lesion was thought to be within the cord (fig 1). No visible syrinx could be seen in the caudal portion of the cord.
In the referring neurosurgical unit, a thoracic laminectomy was carried out in January 2000. However, no intradural abnormality was found; the cord appeared normal. A needle aspiration was performed but no abnormal tissue was identified. Following the surgery, the intercostal pain resolved.
Nine months before referral to our unit, the patient developed numbness in the C8 distribution of the left hand. Examination revealed normal strength in the upper limbs with diminished reflexes in the left arm. There was reduced pinprick sensation from C8 to L4 on the left and from T4 to S4 on the right. Proprioception was affected in the right foot. Clonus was present in the right ankle. The right lower leg was wasted and there was pes cavus deformity. There was grade 3 weakness of right ankle eversion. Spinal examination was normal except for the surgical scar.
Review of the original MRI scan (fig 1) suggested the presence of a dermoid cyst at L2/3 intimately related to the lipomatous tissue. A further MRI scan in 2001 (fig 2) showed that the lipomatous tissue lying within the cord had extended to the C6 level, but that the amount of lipomatous tissue in the lower cord had reduced as compared with the first scan. The nature of this tissue was confirmed as fat by a fat suppression MR sequence. In the lower region of the spinal cord it was now possible to see a syrinx cavity, the presence of which had been obscured by fat on the initial MRI scan.
As the patient’s clinical deterioration had stabilised at this stage, we decided to adopt a conservative policy.
Tethered cord is known to be associated with spinal cord lipomas.1 Terminal lipomas are spinal cord lipomas that are inserted in the end of the conus and incorporated in the filum. They may contain excessive amounts of non-adipose mesenchymal derivatives such as cartilage, bone, and fibrous septums.2 Tethering of the spinal cord can be associated with syringomyelia, probably due to pathological intramedullary pressure changes during movements of the spine.3,4
In this case, we suggest that there was a spontaneous rupture of the possible dermoid cyst into the intramedullary syrinx, allowing migration of fat into the syrinx. This fat was then transported cranially with the CSF flow,5,6 remaining there by virtue of its viscosity.7 It further enlarged and extended the syrinx cranially, and accumulated at the cranial end of the syrinx.
After a careful literature search, we could find no previous description of this. However, Klekamp and Samii illustrated a very similar case in their textbook.7 Intramedullary lipomas do have a potential to change size with the body fat and hence cause neurological symptoms. 1,8 This is the first case report of possible migration of lipomatous tissue within the cord.
We are grateful to Mr J Martin of the Neurosurgical Department, Morriston Hospital, Swansea, UK, for permitting us to present his case.
Competing interests: nono declared
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