Hydroxyapatite laminar spacers and titanium miniplates in cervical laminoplasty.

OBJECTIVE: The authors describe a new surgical technique for cervical laminoplasty that was performed in 25 patients. The posterior elements along with the various ligaments are removed en bloc and are stabilized in a lift-up position by placing hydroxyapatite (HA) laminar spacers and titanium miniplates and screws. The procedure and clinical results are discussed. METHODS: The posterior spinal elements, including the lamina(e), spinous process(es), and various attached ligaments, are removed en bloc by incising the lamina in its lateral aspect. Trapezoid-shaped HA spacers are placed between the cut ends of the laminae or between the laminae and lateral masses bilaterally at each level. Malleable titanium miniplates and screws are used for fixation of the spacers. The fixation of transected laminae was judged to be successful. Postoperative care included application of a soft neck collar for 1 week but no further restriction of activity. Surgery-related outcome was assessed in the 21 patients who attended more than 6 months of follow up after laminoplasty. There were 18 men and three women who ranged in age from 27 to 81 years. Cervical stenotic myelopathy was demonstrated in 15 patients who underwent decompressive and expansive laminoplasty, and spinal tumors were documented in six patients who underwent a nonexpansive laminoplasty. Postoperative and follow-up computerized tomography scans demonstrated no hardware failure. Bone formation around the spacers was observed either at 6- or at 9-month follow-up examination in all 21 patients. Fusion of the reconstructed laminae was found to be completed at 12 months in all 18 patients able to attend follow up for this duration. Spinal alignment and the range of motion of the cervical spine were well preserved. In patients with stenotic cervical myelopathy, neurological and anatomical outcome of canal expansion were satisfactory. CONCLUSIONS: This technique enables rigid laminoplasty while maintaining anatomical and biomechanical integrity of posterior elements of cervical spine. Expansive and nonexpansive laminoplasty procedures are possible.

[Dejerine-Roussy syndrome following endovascular parent artery occlusion for an unruptured posterior cerebral artery aneurysm (P2 segment): case report].

A right posterior cerebral artery (PCA) fusiform aneurysm was incidentally discovered in a 53-year-old man. Although the aneurysm was asymptomatic, treatment of the aneurysm was indicated to avoid possible hemorrhage and/or mass effect. Since the patient tolerated temporary balloon occlusion of the right PCA at P1-P2 segments and sufficient collateral flow to the right temporo-occipital region was observed during such occlusion, parent artery occlusion as well as intraluminal occlusion of the aneurysm was performed with Guglielmi detachable coils. The patient did not develop neurological deficit immediately after embolization. However, he subsequently developed Dejerine-Roussy syndrome due to an infarction in the territory of the thalamogeniculate artery. Parent artery occlusion together with intraluminal aneurysmal obliteration is an useful treatment for a fusiform aneurysm of the PCA. However, ischemic complication in the territory of the perforating artery can not be predicted.

Usefulness of somatosensory evoked magnetic field dipole measurements by magnetoencephalography for assessing spinal cord function.

OBJECT: Objective assessment of sensory function disorders is difficult. In the present study, the authors investigated the possibility of assessing cervical myelopathy-induced sensory disorders by using magnetoencephalography (MEG) to measure somatosensory evoked magnetic fields (SSEMFs). METHODS: In 12 patients with cervical myelopathy, SSEMFs were measured before and after surgery by using a 160-channel helmet-type MEG system to stimulate the median nerve, and the intensity and latency of N20m (first response occurring 20 msec after stimulation) were then determined. Additionally, the severity of the sensory disorder was assessed before and after surgery by obtaining sensory scores determined using the Neurosurgical Cervical Spine Scale. Furthermore, in 11 healthy individuals (control group), the intensity and latency of N20m were measured in the same fashion. Analysis of the results showed that the preoperative intensity of N20m in the 12 patients with cervical myelopathy was significantly lower than that demonstrated in the control patients (p < 0.005, Student t-test). In addition, of six patients in whom sensory scores improved postoperatively, there were significant increases in the intensity of N20m (p < 0.005, paired t-test). Furthermore, there was a significant correlation between sensory scores and dipole intensity (p < 0.001, Spearman correlation coefficient by rank test). CONCLUSIONS: Somatosensory evoked magnetic field measurements determined by MEG are useful in objectively and noninvasively assessing sensory disorders caused by cervical myelopathy.