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Progressive posttraumatic myelomalacic myelopathy: imaging and clinical features.

PURPOSE
To describe the imaging features, surgical management, and clinical outcome of progressive posttraumatic myelomalacic myelopathy (PPMM), a relatively unrecognized but important cause of progressive myelopathy in patients with previous spinal cord injuries.


METHODS
The clinical records, imaging studies, and postoperative outcome of 10 patients with PPMM were reviewed. Fifteen preoperative and five postoperative MRs were analyzed for intramedullary signal abnormalities, the nature of these signal abnormalities, and cord tethering. All patients had intraoperative sonography.


RESULTS
Neurologic signs and symptoms found in our patients included 1) progressive loss of motor function (6/10), 2) sensory level changes (4/10), 3) increased spasticity (4/10), 4) autonomic dysreflexia (4/10), 5) loss of bowel or bladder control (4/10), and 6) local and/or radicular pain (4/10). Preoperative MR in nine patients revealed intramedullary T1/T2 lengthening (9/9), extramedullary tethering/adhesions (9/9), ill-defined lesional borders (6/9), cord expansion (5/9), and increased signal intensity of the lesion on T1-weighted images compared with CSF (7/9). Proton density images in five patients demonstrated a relative increase in signal intensity over CSF. In all five postoperative MRs, there was evidence of untethering of the spinal cord and a decrease in cord size in two patients. Intraoperative sonography revealed cord tethering and abnormal cord echotexture in all cases. Postoperative clinical evaluation revealed neurologic improvement in nine patients.


CONCLUSIONS
PPMM may clinically and radiographically mimic progressive posttraumatic cystic myelopathy (PPCM). MR provides clues to the diagnosis of myelomalacia preoperatively. Intraoperative sonography confirms the absence of a confluent cyst. These points are crucial in the surgical procedures in PPMM vs PPCM. In PPMM, lysis of intradural adhesions results in an improvement in symptoms in a manner similar to the shunting of PPCM.