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H. Michael Mayer and Mario Brock

✓ Percutaneous endoscopic discectomy is a new technique for removing “contained” lumbar disc herniations (those in which the outer border of the anulus fibrosus is intact) and small “noncontained” lumbar disc herniations (those at the level of the disc space and occupying less than one-third of the sagittal diameter of the spinal canal) through a posterolateral approach with the aid of specially developed instruments. The technique combines rigid straight, angled, and flexible forceps with automated high-power suction shaver and cutter systems. Access can thus be gained to the dorsal parts of the intervertebral space where the disc herniation is located. Percutaneous endoscopic discectomy is monitored using an endoscope angled to 70° coupled with a television and video unit and is performed with the patient under local anesthesia and an anesthesiologist available if needed. Its indication is restricted to discogenic root compression with a minor neurological deficit.

Two groups of patients with contained or small noncontained disc herniations were treated by either percutaneous endoscopic discectomy (20 cases) or microdiscectomy (20 cases). Both groups were investigated in a prospective randomized study in order to compare the efficacy of the two methods. The disc herniations were located at L2–3 (one patient), L3–4 (two patients), or L4–5 (37 patients). There were no significant differences between the two groups concerning age and sex distribution, preoperative evolution of complaints, prior conservative therapy, patient's occupation, preoperative disability, and clinical symptomatology. Two years after percutaneous endoscopic discectomy, sciatica had disappeared in 80% (16 of 20 patients), low-back pain in 47% (nine of 19 patients), sensory deficits in 92.3% (12 of 13 patients), and motor deficits in the one patient affected. Two years after microdiscectomy, sciatica had disappeared in 65% (13 of 20 patients), low-back pain in 25% (five of 20 patients), sensory deficits in 68.8% (11 of 16 patients), and motor deficits in all patients so affected. Only 72.2% of the patients in the microdiscectomy group had returned to their previous occupation versus 95% in the percutaneous endoscopic discectomy group. Percutaneous endoscopic discectomy appears to offer an alternative to microdiscectomy for patients with “contained” and small subligamentous lumbar disc herniations.

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Juan Artigas, Mario Brock and Heinz-Michael Mayer

✓ Lumbar disc tissue from eight patients previously submitted to unsuccessful chemonucleolysis with collagenase was studied by light and scanning electron microscopy (SEM). Similar material from eight patients subjected to primary disc surgery served as control. The control discs revealed the characteristic signs of degeneration of collagen tissue, microcystic areas, and giant chondromas. However, the anulus fibrosus and the end-plates remained intact. Following chemonucleolysis with collagenase, “digestion” of the nucleus pulposus, the anulus fibrosus, and extensive damage to the end-plates, bone, ligaments, and epidural fat were seen.

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Michael Payer, Daniel May, Alain Reverdin and Enrico Tessitore

Object. The authors sought to evaluate retrospectively the radiological and clinical outcome of anterior cervical discectomy followed by implantation of an empty carbon fiber composite frame cage (CFCF) in the treatment of patients with cervical disc herniation and monoradiculopathy.

Methods. Twenty-five consecutive patients (12 men, 13 women, mean age 45 years) with monoradiculopathy due to cervical disc herniation were treated by anterior cervical discectomy followed by implantation of an empty CFCF cage. On lateral flexion—extension radiographs segmental stability at a mean follow up of 14 months (range 5–31 months) was demonstrated in all 25 patients, and bone fusion was documented in 24 of 25 patients. The mean anterior intervertebral body height was 3.4 mm preoperatively and 3.8 mm at follow up in 20 patients. In these patients the mean segmental angle (angle between lower endplate of lower and upper vertebra) was 0.9° preoperatively and 3.1° at follow up. In the remaining five patients preoperative images were not retrievable.

Self-scored neck pain based on a visual analog scale (1, minimum; 10, maximum) changed from a preoperative average of 5.6 to an average of 2 at follow up; radicular pain was reduced from 7.7 to 2.1 postoperatively. Analysis of the SF12 questionnaires showed a significant improvement in both the physical capacity score (preoperative mean 32.4 points; follow up 46 points) and the mental capacity score (preoperative mean 45.8 points; follow up 57.5 points).

Conclusions. Implantation of an empty CFCF cage in the treatment of cervical disc herniation and monoradiculopathy avoids donor site morbidity associated with autologous bone grafting as well as the use of any supplementary material inside the cage. Restoration or maintenance of intervertebral height and thus segmental lordosis and a very high rate of segmental stability and fusion are achieved using this technique.

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Joel W. Yeakley, John S. Mayer, Larry L. Patchell, K. Francis Lee and Michael E. Miner

✓ The “delta sign” is a triangular area of high density with a low-density center seen on contrast-enhanced computerized tomography (CT) scans in the location of the superior sagittal sinus. It indicates thrombosis of the sinus. The authors describe the “pseudodelta sign,” which is similar but is seen on non-contrast-enhanced CT scans and which has a high correlation with hemorrhage secondary to acute head trauma.

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Yuri M. Andrade-Souza, Gelareh Zadeh, Meera Ramani, Daryl Scora, May N. Tsao and Michael L. Schwartz

Object. The aim of this study was to validate the radiosurgery-based arteriovenous malformation (AVM) score and the modified Spetzler—Martin grading system to predict radiosurgical outcome.

Methods. One hundred thirty-six patients with brain AVMs were randomly selected. These patients had undergone a linear accelerator radiosurgical procedure at a single center between 1989 and 2000. Patients were divided into four groups according to an AVM score, which was calculated from the lesion volume, lesion location, and patient age (Group 1, AVM score < 1; Group 2, AVM score 1–1.49; Group 3, AVM score 1.5–2; and Group 4, AVM score > 2). Patients with a Spetzler—Martin Grade III AVM were divided into Grades IIIA (lesion > 3 cm) and IIIB (lesion < 3 cm). Sixty-two female (45.6%) and 74 male (54.4%) patients with a median age of 37.5 years (mean 37.5 years, range 5–77 years) were followed up for a median of 40 months. The median tumor margin dose was 15 Gy (mean 17.23 Gy, range 15–25 Gy). The proportions of excellent outcomes according to the AVM score were as follows: 91.7% for Group 1, 74.1% for Group 2, 60% for Group 3, and 33.3% for Group 4 (chi-square test, degrees of freedom (df) = 3, p < 0.001). Based on the modified Spetzler—Martin system, Grade I lesions had 88.9% excellent results; Grade II, 69.6%; Grade IIIB, 61.5%; and Grades IIIA and IV, 44.8% (chi-square test, df = 3, p = 0.047).

Conclusions. The radiosurgery-based AVM score can be used accurately to predict excellent results following a single radiosurgical treatment for AVM. The modified Spetzler—Martin system can also predict radiosurgical results for AVMs, thus making it possible to use this system while deciding between surgery and radiosurgery.