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Shuji Sakata, Fumio Shima, Motohiro Kato and Masashi Fukui

✓ To investigate the mechanism of analgesia noted with electrical stimulation of the thalamic sensory relay nucleus and medial thalamus, modulations of neuronal activities in the periaqueductal gray matter (PAG) were studied in response to electrical stimulations of the ventroposterolateral nucleus (VPL) and parafascicular nucleus (Pf) and to peripheral noxious stimulations in rats. Extracellular single-unit activities were recorded from 102 neurons in the PAG and the adjacent area in animals under halothane anesthesia.

A large population (83%) of the PAG neurons reacted to Pf stimulations with a predominantly excitatory response, whereas smaller numbers (43%) responded to VPL stimulations. There was a significant correlation between the response characteristics of Pf and noxious stimulations, whereas no correlation was found between VPL and noxious stimulations. The PAG neurons that were verified antidromically to project to the nucleus raphe magnus showed a similar pattern of response. The excitatory response to the Pf stimulation was partially attenuated by systemic administration of naloxone, whereas that to the VPL stimulation was not affected.

These results suggest that part of the analgesic mechanism of medial thalamus stimulation involves activation of the descending pain suppression system by exciting the PAG neurons through the opioid system, while the analgesia produced by sensory relay nucleus stimulation does not involve the PAG neurons or the opioid system.

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Jun Masuoka, Shuji Sakata, Kenji Maeda and Toshio Matsushima

The authors report a rare case of pial single-channel arteriovenous fistula presenting with significant brain edema. A 51-year-old woman was admitted with a 5-day history of headache and nausea, followed by consciousness disturbance. Computed tomography showed cerebellar swelling with obstructive hydrocephalus. Magnetic resonance imaging revealed extensive vasogenic edema in the cerebellum bilaterally. Angiography demonstrated 2 different arteriovenous shunts (AVSs) at peripheral branches of the right anterior inferior cerebellar artery. One was located on the suboccipital surface. It drained through a dilated inferior vermian vein and emptied retrogradely into the contralateral cerebellar veins with marked stagnation. Focal stenosis of the dilated draining vein was present. The other AVS was located on the petrosal surface, which had a slow flow with no angiographic evidence of venous congestion. Given that the latter was believed to be asymptomatic, the former AVS was excised, and histological examination revealed that the lesion consisted of a direct communication of multiple arterial feeding vessels with a single vein, consistent with a diagnosis of pial single-channel arteriovenous fistula. The restriction of venous drainage presumably caused venous hypertension, leading to the brain edema and neurological symptoms.

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Fumitaka Yoshioka, Shoko Shimokawa, Jun Masuoka, Tomoko Izaki, Yukiko Nakahara, Masatou Kawashima, Shuji Sakata and Tatsuya Abe

Here, the authors present an extremely rare case of an extensive spinal epidural teratoma (SET) in an infant and provide a review of the cases in the literature. In this report, the authors focused on the clinical manifestation and management of extensive SET. A 64-day-old girl presented with severe dyspnea and paraparesis caused by a large thoracic mass. Imaging studies revealed that the mass originated from the epidural space of the thoracic spine and extended from C7 to L1. The tumor extended bilaterally through the intervertebral foramina and formed a large posterior mediastinal mass. The tumor was partially resected via laminotomy after an emergency thoracotomy. The remnant grade I immature teratoma grew rapidly. After a re-laminotomy and bilateral thoracotomy, the residual tumor stopped growing. However, the patient’s paraparesis improved very little, and her scoliosis progressed gradually. Therefore, SET should be included in the differential diagnosis when an infant patient with paraparesis of the lower extremities is encountered. Timely diagnosis, aggressive treatment, and close monitoring are of critical importance to successful recovery in such patients.

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Tatsuya Tanaka, Atsushi Ogata, Jun Masuoka, Taichiro Mizokami, Tomihiro Wakamiya, Yukiko Nakahara, Kohei Inoue, Shoko Shimokawa, Fumitaka Yoshioka, Nobuaki Momozaki, Shuji Sakata and Tatsuya Abe

OBJECTIVE

Intraplaque hemorrhage (IPH) is most often caused by the rupture of neovessels; however, the factors of intraplaque neovessel vulnerability remain unclear. In this study, the authors focused on pericytes and aimed to investigate the relationship between IPH and pericytes.

METHODS

The authors retrospectively analyzed the medical records of all patients with carotid artery stenoses who had undergone carotid endarterectomy at their hospitals between August 2008 and March 2016. Patients with carotid plaques that could be evaluated histopathologically were eligible for study inclusion. Intraplaque hemorrhage was analyzed using glycophorin A staining, and patients were divided into the following 2 groups based on the extent of granular staining: high IPH (positive staining area > 10%) and low IPH (positive staining area ≤ 10%). In addition, intraplaque neovessels were immunohistochemically evaluated using antibodies to CD34 as an endothelial cell marker or antibodies to NG2 and CD146 as pericyte markers. The relationship between IPH and pathology for intraplaque neovessels was investigated.

RESULTS

Seventy of 126 consecutive carotid stenoses were excluded due to the lack of a specimen for histopathological evaluation; therefore, 53 patients with 56 carotid artery stenoses were eligible for study inclusion. Among the 56 stenoses, 37 lesions had high IPH and 19 had low IPH. The number of CD34-positive neovessels was equivalent between the two groups. However, the densities of NG2- and CD146-positive neovessels were significantly lower in the high IPH group than in the low IPH group (5.7 ± 0.5 vs. 17.1 ± 2.4, p < 0.0001; 6.6 ± 0.8 vs. 18.4 ± 2.5, p < 0.0001, respectively).

CONCLUSIONS

Plaques with high IPH are associated with fewer pericytes in the intraplaque neovessels. This finding may help in the development of novel therapeutic strategies targeting pericytes.