Prospective observational study of acute postlumbar laminectomy MRI.

OBJECT: Patients who develop a lower-extremity neurological deficit after lumbar laminectomy present a diagnostic dilemma. In the setting of a neurological deficit, some surgeons use MRI to evaluate for symptomatic compression of the thecal sac. The authors conducted a prospective observational cohort study in patients undergoing open lumbar laminectomy for neurogenic claudication to document the MRI appearance of the postlaminectomy spine and to determine changes in thecal sac diameter caused by the accumulation of epidural fluid. METHODS: Eligible patients who were candidates for open lumbar laminectomy for neurogenic claudication at a single neurosurgical center between August 2007 and June 2009 were enrolled. Preoperative and postoperative MRI of the lumbar spine was performed on the same MRI scanner. Postoperative MRI studies were completed within 36 hours of surgery. Routine clinical and surgical data were collected at the preoperative visit, during surgery, and postoperatively. Images were interpreted for the signal characteristics of the epidural fluid and for thecal diameter (region of interest [ROI]) by 2 blinded neuroradiologists. RESULTS: Twenty-four patients (mean age 69.7 years, range 30-83 years) were enrolled, and 20 completed the study. Single-level laminectomy was performed in 6 patients, 2-level in 12, and 3-level in 2. Preoperative canal measurements (ROI) at the most stenotic level averaged 0.26 cm(2) (range 0.0-0.46 cm(2)), and postoperative ROI at that same level averaged 0.95 cm(2) (range 0.46-2.05 cm(2)). The increase in ROI averaged 0.69 cm(2) (range 0.07-1.81 cm(2)). Seven patients (35%) had immediate postoperative weakness in at least 1 muscle group graded at 4+/5. The decline in examination was believed to be effort dependent and secondary to discomfort in the acute postoperative period. Those with weakness had smaller increases in ROI (0.51 cm(2)) than those with full strength (0.78 cm(2), p = 0.1599), but none had evidence of worsened thecal compression. On the 1st postoperative day, 19 patients were at full strength and all patients were at full strength at their 15-day follow-up. The T1-weighted epidural fluid signal was isointense in 19 of the 20 patients. The T2-weighted epidural fluid signal was hyperintense in 9, isointense in 4, and hypointense in 7 patients. CONCLUSIONS: Immediately after lumbar laminectomy, the appearance of the thecal sac on MRI can vary widely. In most patients the thecal sac diameter increases after laminectomy despite the presence of epidural blood. In this observational cohort, a reduction in thecal diameter caused by epidural fluid did not correlate with motor function. Results in the small subset of patients where the canal diameter decreased due to epidural fluid compression of the thecal sac raises the question of the utility of immediate postoperative MRI.

Utility of the CO2 laser in the microsurgical resection of cavernous malformations.

OBJECTIVE: The CO2 laser has a long record of use in neurosurgery. However, its utility has been limited by its bulky design and the challenge of using it with the operating microscope. With the development of the OmniGuide fiber, a technology that delivers the beam through flexible hollow-core photonic bandgap mirrors, the laser can now be held and used with greater ease and accuracy. METHODS: We retrospectively analyzed a prospectively maintained database to assess the utility of the laser in 23 consecutive patients (10 male, 13 female; mean age, 40.8 years; range, 9-64 years) with a cavernous malformation treated by the senior author (R.F.S.). RESULTS: Four lesions were located in noneloquent areas, 13 were in the brain stem, four were in the spinal cord, and two were in the thalamus. The usefulness of the laser was rated on a scale of 1 to 5, with 5 defined as "extremely helpful." The mean utility score was 3.5 ± 0.94 (range, 2-5). The laser was judged most useful in creating cortisectomies in eloquent areas and in "shrinking" cavernous malformations away from adjacent hemosiderin-stained tissue. The laser was ineffective against calcification and in obtaining hemostasis. CONCLUSIONS: The CO2 laser is a useful addition to the neurosurgical armamentarium for treating lesions in the brainstem, thalamus, and spinal cord. Its primary utility lies in its ability to create focused cortisectomies safely and to shrink cavernous malformations away from eloquent hemosiderin-stained brain.

Cranial migration of a baclofen pump catheter associated with subarachnoid hemorrhage: case report.

OBJECTIVE: Cephalad migration of an indwelling intrathecal catheter within the spinal canal has rarely been described. Cranial subarachnoid hemorrhage (SAH) related to movement of this type of catheter has not been described. We report a case of SAH coincident with the migration of a free fragment of a baclofen pump catheter into the prepontine cistern. CLINICAL PRESENTATION: A baclofen pump system was removed from a 47-year-old man with spasticity related to multiple sclerosis. A section retained in the spinal canal extended up to the T9 level. Ten days after the pump and lower portion of the catheter were removed, the patient presented with a severe headache and a classic aneurysmal pattern of SAH. The patient's catheter was found to have migrated adjacent to the basilar artery at the level of the superior cerebellar artery. An extensive evaluation, including computed tomography angiography, digital subtraction angiography performed twice, magnetic resonance imaging, and magnetic resonance angiography, showed no apparent cause for the hemorrhage. Initially, the catheter was left in place. However, 5 months after the SAH, the patient elected to have the catheter removed. INTERVENTION: The catheter was pulled out from below through a C6-C7 laminoplasty without complications. The patient made an excellent recovery. DISCUSSION: Cephalad catheter migration is a rare phenomenon. The mechanism of rostral migration remains unclear. The forces that propel a free fragment of catheter under these circumstances seem to be sufficient to cause a small vessel to rupture and bleed. Given the lack of an observed arterial injury, we postulate that venous bleeding caused this hemorrhage.