The present paper deals with the effect of impulse noise, which is produced by launching of miniature tactical missiles, on hearing of guinea pigs situated in the control room of the missile launching vehicle. 20 normal hearing guinea pigs are placed in the control room in which impulse noise level is 160-170dB (sound pressure level) and duration is longer than Is. 48h after sound exposure, the mean threshold shift is 2 dB, and threshold shift of 2/40 ears is greater than 10dB. Histological observation reveals that cochlear hair cells are undamaged in 15 ears. Howeves, staining on bloc shows hydrops of cochlear partition in 5 ears.

Objective:To compare the optimal gridpercutaneous vertebroplasty (PVP) and conventional PVP in the treatment of osteoporotic vertebral compression fractures (OVCFs).Methods:A retrospective cohort study was conducted of 102 patients with OVCFs who had underwent PVP between May 2016 and May 2019 at department of spine surgery, General Hospital of Northern Theater Command. According to the different surgical methods, they were divided into the optimalgrid PVP group (102 cases) and conventional PVP group (94 cases). In the optimal grid PVP group, there were 38 males and 64 females with an average age of 67.3±8.5 years old, and the course of disease was 2.3±1.2 days; the injured sites were lumbar vertebra, including 59 cases of L 1 vertebra, 31 cases of L 2 vertebra, 8 cases of L 3 vertebra, 3 cases of L 4 vertebra and 1 case of L 5 vertebra. In the conventional PVP group, there were 26 males and 68 females with an average age of 71.5±5.6 years old, and the course of disease was 2.1±1.1 days; the injured sites were lumbar vertebra, including 52 cases of L 1 vertebra, 33 cases of L 2 vertebra, 7 cases of L 3 vertebra and 2 cases of L 4 vertebra. The patients were prepared before operation. Then the best puncture point was selected, and the guide wire and working channel were inserted. Finally the bone cement was pushed. The operation time, intraoperative fluoroscopy times, bone cement dosage and bone cement leakage were compared between the two groups. Visual analogue scale (VAS), anterior heights and median heights of injured vertebra were compared between the two groups at postoperative 3 days, 3 months and the final follow-up. Results:There were no significant differences in the general clinical data between the two groups before operation ( P>0.05). All patients had no complications such as wound infection,pulmonary embolism,spinal cord embolism or death. The operation time, fluoroscopy times, bone cement dosage and bone cement permeability of the two groups were statistically significant different ( P<0.05), and the optimal grid group was better than the conventional group. VAS at 3 days, 3 months and the final follow-up was statistically significantlower in the optimal grid group than the conventional group ( P<0.05). There was no significant difference in the recovery of the anterior and middle edge heights of injured vertebra in the two groups 3 days after operation ( P>0.05), but there were statistical significant difference between the two groups3 months after operation and at the last follow-up ( P<0.05), whilethe optimal grid group was better than the conventional group. Conclusion:Compared with conventional PVP, the optimal grid PVP is safer and more effective in the treatment of osteoporotic vertebral compression fractures.

Objective To establish standard sites for bur holes that maintain constant anatomical relationships with the skull base and neural structures and can serve as the basal aspect of supratentorial temporooceipital craniotomies such as subtemporal transpetrosalridge approach.Methods To determine cranial-cerebral relationships,the authors delimited 10 adult cadaveric skulls anteriorly and posteriorly the external projection of the petrous bone and the midbrain by CT and Titanium nail.Then bur holes in adult cadaveric skulls were created (kl,the first bur hole,located anterior to the auricle of the ear; k2,the second bur hole,whose base was located 1 cm above the interface of the parietomastoid and squamous sutures; k3,the third bur hole whose base was located 1cm above the asterion).Three bur holes were made on each of the skulls (20 cerebral hemispheres).The author then introduced plastic catheters through the bur holes to evaluate pertinent cranial and neural landmarks.Results The first bur hole appeared to have a particular anatomical relationship with the anterior aspect of the petrous portion of the temporal bone and the most anterior aspect of the midbrain.The second bur hole had a particular relationship with the posterior border of the petrous portion of the temporal bone and with the posterior aspect of the midbrain.The third bur hole was mostly supratentorial and particularly related to the preoccipital notch.Conclusions The middle fossa floor is located anterior to the site of the kl,and the superior surface of the tentorium is posterior to k2.Together with k3,these bur holes can be considered standards for temporooccipital craniotomies such as subtemporal transpetrosalridge approach.