Microendoscopic discectomy (MED) is one of the minimally invasive endoscopic procedures for treating lumbar disc herniation. We have applied MED techniques to posterior decompression procedures for treating lumbar spinal stenosis (LSS). In the present study, we examined the surgical complications in 114 consecutive patients surgically treated with MED procedures for LSS. Intraoperative complications occurred in 9 patients. Six patients (5.3%) experienced a dural tear, and three (2.6%) had a fracture of an inferior facet. Early postoperative complications occurred in 13 patients. Twelve patients (10.5%) experienced transient neurological complications. The clinical outcomes at the mean 28-month follow-up were not affected by these surgical complications. Other major complications such as nerve injury and surgical site infection were not observed. Most of the complications occurred in the initial series of patients, and the incidence of complications decreased with an increase in the surgeon's experience and the application of several preventive measures against the complications. The surgeon should undergo training when MED techniques are applied in surgical treatment in order to recognize the specific complications associated with such procedures and apply preventive measures against these complications.

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We examined the reliability of radiological findings in predicting segmental instability in 112 patients (56 men, 56 women) with a mean age of 66.5 years (27 to 84) who had degenerative disease of the lumbar spine. They underwent intra-operative biomechanical evaluation using a new measurement system. Biomechanical instability was defined as a segment with a neutral zone > 2 mm/N. Risk factor analysis to predict instability was performed on radiographs (range of segmental movement, disc height), MRI (Thompson grade, Modic type), and on the axial CT appearance of the facet (type, opening, vacuum and the presence of osteophytes, subchondral erosion, cysts and sclerosis) using multivariate logistic regression analysis with a forward stepwise procedure. The facet type was classified as sagittally orientated, coronally orientated, anisotropic or wrapped. Stepwise multivariate regression analysis revealed that facet opening was the strongest predictor for instability (odds ratio 5.022, p = 0.009) followed by spondylolisthesis, MRI grade and subchondral sclerosis. Forward stepwise multivariate logistic regression indicated that spondylolisthesis, MRI grade, facet opening and subchondral sclerosis of the facet were risk factors. Symptoms evaluated by the Short-Form 36 and visual analogue scale showed that patients with an unstable segment were in significantly more pain than those without. Furthermore, the surgical procedures determined using the intra-operative measurement system were effective, suggesting that segmental instability influences the symptoms of lumbar degenerative disease.

The lateral line system and its innervation were examined in the ostraciid Ostracion immaculatus (Tetraodontiformes), and compared with those in the triacanthodid Triacanthodes anomalus (Tetraodontiformes) and the acropomatid Malakichthys wakiyae (Perciformes). The carapace of O. immaculatus was composed of 6 cephalic and 2 trunk lateral lines, all neuromasts being categorized as "superficial." Triacanthodes anomalus was identical with O. immaculatus in the absence of the mandibular line and its innervating ramus, whereas in M. wakiyae the line and ramus were present. All neuromasts were "superficial" in the former two, but "canal" in the latter. Judging from the essentially identical lateral line topography and innervation patterns in all three species, the superficial neuromasts in the two tetraodontiforms were considered to have resulted from replacement of canal neuromasts. The number of neuromasts in the cephalic lateral lines of O. immaculatus (106) and T. anomalus (91) were similar, being significantly higher than in M. wakiyae (30). However, the reverse was true for the trunk lateral lines, the two tetraodontiforms having fewer neuromasts (39 in O. immaculatus, 47 in T. anomalus) compared with M. wakiyae (59).lateral line system, most likely owing to its inconspicuous nature. Overall, the system has not been utilized positively for either taxonomic or phylogenetic characters, although the statement that infraorbitals are absent in the order (Tyler, 1980) may be interpreted as an indirect reference to the lateral line system. Although Bal (1937) studied the nervous system of Takifugu oblongus, details were omitted in the description.In this study, the lateral line system and its innervation are described and illustrated in detail for the first time in the Tetraodontiformes. As a first step in tetraodontiform neuroanatomy, we examined two "extremes" to roughly estimate the stability of the lateral line system and its innervation within the order: Ostracion immaculatus (Ostraciidae) for its specialized "scutes" with a three-dimensional collagen network structure (Besseau and Bouligand, 1998) and Triacanthodes anomalus (Triacanthodidae) for its primitive position in the order (Santini and Tyler, 2003). Furthermore, the perciform Malakichthys wakiyae is described and illustrated as a comparative reference to tetraodontiform conditions, a sister-group search not being attempted in this study.

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