Split cord malformation with dorsally located bony spur: Report of four cases and review of literature

Split cord malformations (SCM) with a dorsally located bony spur are a very rare entity. The authors report a series of four such cases. The literature is reviewed regarding the pathogenesis and management of this uncommon variant of SCM. The presenting features include – scoliosis with motor and autonomic dysfunction (n = 1), scoliosis with cutaneous patch (n = 1), hypertrichotic area (n = 1), and motor deficits alone (n = 1). The location of spur was thoracic and lumbar in two patients (50%) each. Low-lying conus was present in three patients. Long segment syrinx was present in one patient. With respect to the bony anomalies, two patients had a hypertrophied posterior arch (HPA) and one patient had a dysraphic spine. All patients underwent surgical excision of the spur with detethering, if a low-lying conus was present. Two patients developed transient worsening of the neurological status after surgery which recovered at the time of the last follow-up; in both these patients, there was a HPA and a low-lying conus. Surgical excision of the spur with detethering of filum, in cases of low-lying conus, is the treatment of choice. Risk of post-operative worsening of the neurological status is increased in cases in which there is concomitant presence of HPA.