Hydatid disease of spine: Multiple meticulous surgeries and a long term followup.

We present a long term followup (13 years) of spinal hydatid disease with multiple recurrences and intradural dissemination of the disease at the last followup. Intradural extension of the disease in our case was supposedly through the dural rent which has not been reported in English literature. An early followup of the same case has been reported previously by the authors. A 53 year-old female came with progressive left leg pain and difficulty in walking since 2 months. On examination, she had grade four power of ankle and digit dorsiflexors (L4 and L5 myotomes) on the left side (Medical Research Council grade). There was no sensory loss, no myelopathy and sphincters were intact. Plain radiographs showed consolidation at D10-D11 (old operated levels) with stable anterior column and there were no implant related problems. Magnetic resonance imaging showed a cystic lesion at L3-L4, signal intensity same as of cerebrospinal fluid in T2 and T1, displacing the cauda equina roots. The proximal extent of the lesion could not be identified because of artifacts from previous stainless steel instrumentation. Computed tomography myelogram showed complete block at L3-L4 junction with "meniscus sign". This is the longest followup of hydatid disease of the spine that has ever been reported. Hydatid disease should always be included in the differential diagnosis of destructive or infectious lesions of the spine. Aggressive radical resection whenever possible and chemotherapy is the key to good results. Recurrence is known to occur even after that. Disease can have long remission periods. Possibility of intradural dissemination through dural injury is highly likely. Hence, it should always be repaired whenever possible.