Spinal Arteriovenous Metameric Syndrome

Cobb syndrome is defined by the association of vascular cutaneous (venous or arteriovenous), muscular (arteriovenous), osseous (arteriovenous) and medullary (arteriovenous) lesions at the same metamere or spinal segment. This segmental distribution may involve one or many of the 31 metameres present in humans. Only 16% of the medullary lesions are multiple and have a clearly metameric distribution.

Epidemiology

Less than 100 cases of Cobb syndrome have been reported in the literature. There is no sex predilection. Cobb syndrome represents less than 15% of cases of spinal cord arteriovenous malformations.

Clinical description

The neurological symptomatology is comparable to that observed with acute haemorrhagic accidents or with chronic venous congestion of the spinal cord. The extent of the associated deficit depends on the localisation (cervical, thoracic, lumbar or sacral). These manifestations most often involve the lower limbs and are characterised by bilateral motor or sensory asymmetric deficits associated with sphincter anomalies. The morphological manifestations may be partial (appearing incomplete) in cases were some of the localisations at the same metamere are absent. The cutaneous manifestations of the syndrome are most often flat vascular lesions (port-wine stains) but angiokeratomas, angiolipomas and lymphangiomas have been reported. The medullary lesions are arteriovenous malformations. The muscular and osseous lesions may cause nonmechanical localised pain but are often asymptomatic.

Etiology

The syndrome is not familial or hereditary and no chromosomal anomaly has been described. The primitive events causing the disorder occur during early embryogenesis and involve a group of precursor vascular cells before the stage of migration to their definitive cell territories (skin, bone, peripheral nerve or spinal cord). Two consecutive territories may be affected resulting in multimetameric forms of the disease. Recent analysis of Cobb syndrome has led to use of the term Spinal Arteriovenous Metameric Syndrome 1-31 (SAMS 1-31), by analogy with the Cerebrofacial Arteriovenous Metameric Syndromes (CAMS 1-3) and the Cerebrofacial venous metameric syndromes (CVMS1-3).

Diagnostic methods

Diagnosis is made by MRI, supplemented by medullary angiography.

Management and treatment

Treatment of the osteomuscular malformations involves embolisation (endovascular navigation and occlusion of the arteries feeding the malformation using a biological glue) and/or surgery. Laser treatment is used for associated superficial cutaneous lesions. Radicular or medullary malformations are treated by embolisation. Indications for classic surgery are restricted to certain localisations and superficial lesions, epidural and paraspinal injections can be used if the endovascular approach fails. Radiotherapy is not indicated. Early diagnosis reduces the extent of the neurological deterioration, in particular paralysis.

Prognosis

The disease course is unpredictable and the lesions may remain asymptomatic for long periods of time.