Oka strain of varicella zoster virus (VZV) was isolated from vesicles of a 3-year-boy who had developed typical varicella symptoms. It was passaged 11 times in human embryonic lung fibroblasts (HEL) at a rather low temperature of 34°C and 12 times in guinea pig embryo fibroblasts (GPEF) at 37°C. GPEF was the only susceptible non-primate cells; where in some degree of viral replication was noticed. The resultant virus was somewhat temperature sensitive (virus titer at 38°C is lower than that of parental virus), and showed host dependency (more affinity to GPEF); the ratio of virus titer in GPEF/HEL was higher than parental virus. The passaged virus was used as a candidate varicella vaccine and was found safe and effective in normal children and in immunocompromised children with good protective immunity.
Oka varicella vaccine strain was provided to Merck (USA) and RIT-SKF (currently GSK, UK) and licensed in 1984 for high risk children in several countries in Europe by RIT-SKF, then in Japan in 1986 for normal children as well as high risk children, followed by Korea in 1988 similarly as in Japan. In 1995, universal immunization was approved in the USA. Currently, Oka varicella vaccine is widely approved and used throughout the world.
In follow-up of vaccinated children with acute leukemia, the incidence of zoster was fewer in those with no rash after vaccination as compared with those who were rash positive. (5/247 [2.0%] versus 13/83 [15.7%]). Similar results were noted by the US Study Group on varicella vaccine. Usually, no or few rash appears in normal children. From the viewpoint of pathogenesis of herpes zoster, it may be expected that the incidence of herpes zoster would be lower in vaccine recipients in future as compared with those experieing natural varicella.
In 2003, it was recognized in Japan that immunization of elderly individuals with commercially available varicella vaccine (≥30, 000 PFU/dose) enhanced their immunity against VZV, particularly cell-mediated immunity. Hence elderly patients with decreased cell-mediated immunity against VZV were added as the target subjects of varicella vaccination. It was reported in the USA in 2005 that immunization of older adults with high-titered (mostly 32, 000 PFU/dose) varicella vaccine resulted in 61-66% preventive effect of herpes zoster and postherpetic neuralgia (PHN).

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Pain intensity in patients with postherpetic neuralgia can be influenced by psychological factors; however, there are few reports that studied psychological aspects of patients with postherpetic neuralgia. Therefore we performed a series of four psychological tests, the Cornell Medical Index (CMI), the Manifest Anxiety Scale (MAS), the Self-rating Depression Scale (SDS), and the Yatabe-Guilford Personality Test (YG), in patients with postherpetic neuralgia (n=30). These results were compared with those of healthy younger (n=30) and elderly volunteers (n=30). In the CMI, 43% of the patients revealed neurotic tendencies. They also had hopelessness or anger. In the MAS, 24% of the patients showed anxiety or severe anxiety. However, there were no statistically significant differences between the patients and the younger or elderly volunteers. In the SDS, the scores in the patients and younger and elderly volunteers were 43±7, 31±6, and 34±9, respectively. The mean score in the patients was significant higher than that of younger or elderly volunteers, suggesting that the patients were in a depressive state. In the YG, there was no peculiar personality tendency in the patients. We conclude that the patients with postherpetic neuralgia in our study were neurotic, hopeless, and in anger.

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We report three lower limb amputees with phantom pain who were treated with intravenous elcatonin. Case 1: A 36-year-old man underwent right below-knee amputation after a traffic accident. We administered elcatonin intravenously for stump and right heel pain. After four cycles of elcatonin administration (one cycle was 100 IU of intravenous elcatonin dayly for 3 days), the right heel pain disappeared. Case 2: A 41-year-old man underwent right below-knee amputation because of diabetic gangrene. Pain in the phantom toes appeared on postoperative day 6. The pain reduced from 10 to 4 on a numerical rating scale (NRS) of pain after one cycle of intravenous elcatonin administration. Case 3: A 57-year-old man under-went left below-knee amputation followed by above-knee amputation due to atherosclerosis obliterans. Phantom pain in the left leg with radiation to the toes occurred. The pain was 10 on NRS. After 10 cycles of elcatonin administration, the pain decreased from 10 to 5 on NRS. We conclude that intravenous elcatonin may be effective in some selected patients with phantom limb pain.

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I report a patient with neuropathic pain in the alveolar process of the mandible treated with Keishikajutsubuto and Neurotropin^®. A 36-year-old woman developed pain in the alveolar process of the mandible after pulpectomy of the right mandibular first molar tooth 2 years 7 months before. She was referred to our clinic because of prolonged pain. There was persistent ongoing pain and mechanical allodynia, which was provoked by light touch in the painful region. The patient was diagnosed as having neuropathic pain of the alveolar process of the mandible after injury to the inferior alveolar nerve. Keishikajutsubuto and Neurotropin^® were administered. Although slight uncomfortable sensation and paresthesia persisted in the gingiva, the pain disappeared 8 months after start of medication. Keishikajutsubuto and Neurotropin^® may be useful in some patients with neuropathic pain after pulpectomy.

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We report an otherwise healthy patient who developed epidural infection during continuous epidural block. A man in his fifties with lumbar disc herniation received continuous epidural block for the treatment of pain in the low back and lower extremity. After disinfection of the skin with 0.5% chlorhexidine in 80% alcohol, an epidural catheter was easily inserted through L5/S1 intervertebral space. The site of epidural catheter insertion was disinfected with 0.5% chlorhexidine in 80% alcohol every morning. On the 12th day after epidural catheterization, fever and pain at the epidural puncture site developed. Headache, back pain, and pyrexia of 38.1°C developed next day. The epidural catheter was removed. Magnetic resonance imaging (MRI) suggested the presence of an epidural abscess at the L5 level. Headache and pyrexia improved after intravenous administration of antibiotic. Bacterial culture of the epidural catheter tip yielded Staphylococcus epidermidis. MRI performed one month later showed resolution of the epidural abscess. Physicians should pay a keen attention to the epidural infection even in otherwise healthy patients when an epidural catheter is inserted.

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We report a patient having unrecognized epidural metastasis from prostate cancer who developed a slowly progressive paraplegia during epidural analgesia for postoperative pain treatment. A 69-year-old man was scheduled for laparoscopic cholecystectomy. After an epidural catheter was inserted through T10-11 intervertebral space, anesthesia was maintained with general anesthesia combined with epidural anesthesia. Bupivacaine of 0.25% was infused postoperatively at a rate of 2ml/h through the epidural catheter. On postoperative day (POD) 1, the patient complained of numbness in the left lower limb. Epidural infusion of bupivacaine was withheld and the epidural catheter was removed. On POD 3, he noted mild decrease of muscle strength in both lower limbs. On POD 5, slowly progressive paraplegia below T9 with total sensory loss except for warm sensation developed. Magnetic resonance imaging (MRI) revealed multiple bone metastases in the thoracic vertebrae, and fat-suppressed T2-weighted MRI showed that an epidural mass compressed the spinal cord at T8 level. Emergency laminectomy and spinal fixation were performed six hours after the onset of paraplegia. Pathologic examination showed that the tumor was metastatic anaplastic adenocarcinoma from the prostate. The muscle power recovered in two weeks postoperatively. He was discharged two months after the surgery, without motor impairment of the lower limbs.

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