Quantitative assessment of surgical decompression of the cervical spine with cine phase contrast magnetic resonance imaging

OBJECTIVE: We measured cerebrospinal fluid flow velocity by use of cine phase contrast magnetic resonance imaging to quantitate the effectiveness of surgical decompression in patients with cervical myelopathy. METHODS: Forty-seven patients with cervical myelopathy attributable to either spondylosis or ossification of the posterior longitudinal ligament were studied. Thirty-five patients underwent anterior cervical decompression and fusion; 12 others underwent expansive laminoplasty. Patients were examined preoperatively and postoperatively by use of a 1.5-T scanner with a pulse-gated cine phase contrast sequence. Cerebrospinal fluid flow direction and velocity in the ventral subarachnoid space were determined at the C1 and T1 levels. Forty-four healthy control subjects were examined to determine normal flow velocity parameters. Severity of cervical myelopathy was evaluated preoperatively and postoperatively by use of Japan Orthopedic Association scores to calculate the extent of recovery. RESULTS: Preoperatively, cerebrospinal fluid flow velocity in the caudal direction was significantly lower at both C1 and T1 than velocities measured in healthy controls. Both decompressive procedures essentially returned patient velocities to control values. Clinical recovery from myelopathy did not differ between anterior and posterior decompression. Postoperative increase in flow velocity correlated with clinical recovery after posterior (P < 0.0008) but not anterior decompression. CONCLUSION: Cine phase contrast magnetic resonance imaging provides quantitative assessment of cervical spine decompression, with particularly good clinical applicability to posterior procedures.