OBJECTIVE To describe the later neurologic deterioration secondary to the appearance of a post-traumatic syringomyelic cavity, in a patient who, in the initial phase, had an incomplete spinal cord lesion (ASIA C), which improved to ASIA E. METHODS A 52-year-old male patient who, at the age of 19 (1965), suffered a spinal cord injury. He presented with a fracture of the sixth and seventh cervical neurological segment at the time of the lesion, evolving to ASIA E. Nine years after the traumatism, he began to feel pain accompanied by a sensory and motor deficit. RESULTS With the aid of myelography and MRI, the existence of a syringomyelic cavity was detected, which extended from the fourth to the seventh cervical segments. The patient was operated on, on various occasions, placing a syringo-subarachnoid shunt. The neurological status of the patient continued to deteriorate and, at present, he has a complete lesion below the fourth neurological cervical segment with a partially preserved sensitive area up to T1. CONCLUSIONS The development of the syringomyelic cavity could be one of the causes of later neurologic deterioration in patients with traumatic spinal cord injury with neurological recovery 'ad integrum' in the initial phase of spinal cord injury.