Combined endovascular and surgical management of a case of Cobb syndrome

Background

Cobb syndrome is a rare segmental neurocutaneous disease with poorly understood pathophysiology and unknown natural history. The exact incidence is not known with less than 50 cases reported in literature.1 2 These patients have spinal and soft-tissue/cutaneous vascular malformations in a metameric segmental distribution. Cutaneous involvement is characterised by presence of haemangiomas, vascular malformations and naevi. Mostly, it presents clinically in late childhood with cutaneous stigmata, sensory/motor neurological deficits and pain. The spinal vascular malformations usually have complex angioarchitecture and complete obliteration of the spinal lesion is not possible in most of the cases. So, these cases are treated with intent to halt the progress of neurological deficits rather than to cure it.

Case presentation

A 5-year-old male child presented with sudden onset gradually progressive weakness in bilateral lower limbs and pain in lower back for 2 weeks. The patient had to put excessive strain during micturition and defecation for last 1 week. There was no history of trauma, fever, seizure or spinal surgery. On clinical evaluation, the patient was conscious, oriented and his higher mental functions were intact. There was symmetric paraparesis (bilateral lower limb power—3/5 at hip, 4/5 at knee and 1/5 at ankle), decreased sensation below the level of groin bilaterally and loss of bladder and bowel control. A large maculopapular cutaneous lesion was noted in lower back and gluteal region. The cutaneous lesion was present since birth and progressively increasing in size with the growth of body size of the patient (figure 1A).

Investigations

The patient underwent MRI of spine which showed multiple T2 hypointense serpiginous flow voids in the spinal canal with a large sac like structure at D12 vertebral level compressing over posterior surface of the lower spinal cord. There was associated lower spinal cord oedema. A fluid-fluid level was seen in sacral spinal canal suggestive of subarachnoid haemorrhage (figure 1B–D). A T2 hyperintense and T1 hypointense avidly enhancing lesion was seen in paraspinal muscle on right side suggestive of haemangioma (figure 1E–H). Subsequently, the patient underwent diagnostic digital subtraction angiography (DSA) which showed spinal perimedullary arteriovenous fistula (AVF) supplied by posterior spinal arteries (PSA) arising from radiculo-pial branches of posterior intercostal arteries at right L3, right D11 and left D10 vertebral levels. The fistula was also fed by small branches of anterior spinal artery (ASA) arising from radicle-medullary branch of posterior intercostal artery at left D9 vertebral level. The drainage was in dilated perimedullary veins (figure 2A–E). A large venous sac was seen at D12 vertebral level at the site of fistula. Abnormal vascular blush was noted in the region of right paraspinal muscle and gluteal region which was supplied predominantly by branches of right posterior intercostal artery at L3 vertebral level (figure 2D–E). Small feeders to the haemangioma were also coming from right posterior intercostal artery at L2 vertebral level and right internal iliac artery. The DSA findings were consistent with type IVc perimedullary spinal AVF (anatomical location-based classification) with haemangioma in right paraspinal muscle and gluteal region. Based on the clinical features, MRI and DSA findings, a diagnosis of Cobb syndrome with subarachnoid haemorrhage in spinal canal and compressive myelopathy from dilated venous sac at fistula site was made.

Treatment

The patient was taken for endovascular embolisation of the spinal AVF and paraspinal muscle haemangioma. Under general anaesthesia, through right transfemoral route, right D11 and L3 posterior intercostal arteries were sequentially accessed. The PSAs, supplying the AVF were super selectively cannulated and 1.2F microcatheters were advanced up to the fistula site. Then the AVF was embolised using n-butyl cyanoacrylate:lipiodol (1:2.5 dilution) solution ensuring that the liquid embolising agent reaches into the venous sac as well as the immediate draining vein of the AVF (figure 2F–G). Postprocedure DSA showed near complete embolisation of the AVF and patent ASA and PSAs (figure 2H–J). Then the arterial feeders from right L3 and L2 posterior intercostal arteries and right internal iliac artery which were supplying the haemangioma were selectively cannulated and embolised using 300–500 μm poly vinyl alcohol particles. A sketch diagram depicting the angioarchitecture of the spinal AVF in this case is provided (figure 3).

The patient was taken for surgery the next day. The surgical procedure involved laminectomy of D11–L1 levels. The epidural space was normal in appearance. The dura was opened in the midline. The embolised AVF was located subpially. Due to embolisation, the AVF mass was avascular, firm and easy to handle during surgery. This embolised AVF mass was elevated from the dorsal aspect of the cord, starting cranially and then proceeding caudally. The gliotic plane between the lesion and the underlying spinal cord was exploited to remove the fistula. In the central part of the lesion, an embolised large venous sac was seen piercing the spinal cord which was communicating with the ventral subdural space. This was divided in line with the rest of the lesion, leaving behind an embolised stump of the venous sac. Embolised venous channels were also removed to free the exiting nerve roots from the conus medullaris. During the entire procedure, somatosensory evoked potential and motor evoked potentials were monitored for physiological monitoring and function preservation. Intra-operative indocyanine green dye showed no filling of abnormal vessels (figure 4A–F).

Outcome and follow-up

Postsurgery, the patient showed gradual improvement in bilateral lower limb power and sphincteric functions. The lower limbs power improved to 3/5 at hip, 4/5 at knee and 3/5 at ankle.

At discharge, the postoperative wound was healthy and the patient was able to void voluntarily. The patient has both subjective and objective improvement at 4 months follow-up. The sphincteric functions have further improved while the power in the lower limbs have improved to 4/5 at hips, 4+/5 in the knees while it has remained the same in bilateral ankle joints.