METHODS This is a case report. OBJECTIVE Two patients with noncommunicating syringomyelia manifesting symptoms years after the uneventful excision of a benign intradural extramedullary neoplasms are presented. BACKGROUND The association of noncommunicating syringomyelia with benign extramedullary neoplasms as a coexistent or delayed process is a rare event. The pathogenesis of such spinal cord cavitation after tumor removal and the relationship with therapeutic intervention is not well defined. METHODS The delayed occurrence of neurologic impairment emphasizes the need for considering development of syringomyelia rather than tumor recurrence. RESULTS The effects of chronic spinal cord compression in the thoracic region may be accelerated by adverse stresses acting on the spinal cord associated with tethering of the spinal cord. CONCLUSIONS In defining the pathogenesis of this form of spinal cord cavitation, these cases suggest that therapeutic approaches directed at resolving the process should not only include lyses of adhesions, but shunting procedures, which appear to be most efficacious when these procedures are performed at or cephalad to the level of original tumor removal.