There is increasing evidence that nerve growth factor (NGF) plays a role in the prolonged pain associated with inflammation and thus promotes the development of chronic pain. An increase in the tissue level of NGF occurs within hours of the initiation of inflammation. NGF produces prolonged thermal and mechanical hyperalgesia. The thermal hyperalgesia results in part from sensitization of nociceptors, while mechanical hyperalgesia involves central changes. NGF locally produced by inflammation is retrogradely transported to the dorsal root ganglion (DRG) and triggers the upregulation of vaniloid receptor-1, tetrodotoxin-resistant Na⁺ channels, brain-derived neurotrophic factor (BDNF), calcitonin gene-relatedpeptide (CGRP) and substance P within the cell bodies of nociceptive primary sensory neurons in DRG. BDNF is transported to central terminals in dense core vesicles and released from central terminals. BDNF in turn phosphorylates NMDA receptors, and mediates the hyperexcitability of secondary nociceptive neurons within the spinal cord.
Pain of postherpetic neuralgia (PHN) is often of 3 types; ongoing pain, superimposed paroxysmal pain and allodynia. There are sensory deficits affecting all modalities in the involved dermatomes, indicative of partial deafferentation. Topically applied lidocaine relieves pain in some PHN patients. It is likely that ectopic impulses are generated from surviving axons and induce hypersensitivity of secondary nociceptive neurons in such cases. Allodynia is most often elicited by innocuous moving, and the mechanical allodynia appears to be mediated by large tactile fibers. This implies abnormal synaptic connectivity at the spinal cord level between large afferent fibers and central pain signalling secondary neurons. The windup response of wide dynamic range (WDR) neurons which normally occurs in response to repetitive C fiber stimulation through activation of NMDA receptors, may be brought about by large tactile fiber inputs in PHN. This may account for the windup of tactile allodynia in PHN.

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Management of cancer pain is one of the important missions of pain-clinicians. Pain-clinicians should understand “WHO guidelines for cancer pain relief” thoroughly and use them efficiently for the cancer pain patients. Because terminal cancer patients have only limited time of life, their pain and suffering should be relieved as soon as possible. Therefore pain-clinicians should improve their skill to diagnose and treat the cancer pain, and communicate with the patients frankly but thoughtfully.

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The blink reflex has distinct advantages over the conventional tests because it reflects the functional status of the entire nerve, including the intratemporal segment, which is known to be the most fragile portion of the facial nerve. The aim of this study is to compare the accuracy in judging the severity of facial palsy between ENoG and blink reflex and to evaluate the utility of analysis of R1 wave in blink reflex as prognostic indicator for patients with facial palsy.
Electroneuronography (ENoG) and blink reflex (amplitude and latency of R1 wave) were carried out in 50 patients. The patients treated by stellate ganglion block were classified into three groups: Group I scored more than 90 points (full score is 100 points) within 2 weeks, Group II scored more than 90 points over 2 weeks, and Group III scored less than 90 points. The examinations were performed at the first visit, and 10 days, 2, 4, 6 weeks after the onset of facial palsy.
There were no significant differences of ENoG amplitude in three groups at the first visit and 10 days after the onset of disease. The patients whose R1 wave were obtained at the first visit were seen in Group I and Group II, but not in Group III. Recovery of R1 amplitude was dependent on the degree of cure of patient's disorder.
The results of this study indicate that analysis of R1 latency and amplitude of blink reflex provide valuable information for evaluation of the prognosis of patients with peripheral facial palsy.

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A 64-year-old male patient, resident of Kochi prefecture where an endemic of filariasis had once happened, suffered from chyluria due to filariasis at the age of 29 and two incidences of hematochyluria at the age of 59 and 63. He visited neighbor hospital due to severe pain from herpes zoster in the left fourth cervical nerve area and was given prescription of anti-virus drug, nonsteroidal anti-inflammatory agents and oral dose of 75mg/day of amitriptyline. However, he suffered again from severe pain. He was then referred to our pain clinic department in order to relieve the pain. Stellate ganglion block and continuous cervical epidural block were performed and oral dose of 400mg/day of carbamazepine was administered simultaneously. These measures gradually reduced frequency, severity and duration of the pain, then it totally disappeared. However, sudden urinary retention occurred on the fifth hospital day. Urinalysis showed hematochyluria, including abundant white gelatinous contents and blood clots. Urethral catheterization was done several times because of catheter blockage due to recurrent hematochyluria. After administration of amitriptyline and carbamazepine was discontinued, hematochyluria gradually improved.
Filaria has already been eradicated in Japan, but chyluria still appears at chronic stage of filariasis. Parasitic hematochyluria is caused by the compression or obstruction of the lymphatic vessels and leakage of chylus into urine through the fistula with blood from the lymphatic vessels to the urinary system caused by parasitism of Wuchereria bancrofti. This case suggests the necessity of precautionary administration of anticholinergic drugs such as amitriptyline and carbamazepine to patients with filariasis because of the possibility of hematochyluria.

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We report a subarachnoid cyst in a 66-year-old woman who was evaluated with MRI after epidural anesthesia for gynecological surgery. Three days after the continuos epidural analgesia for the postoperative pain, the patient complained of motor weakness, hypesthesia and dysesthesia in both legs. An epidural hematoma was suspected with MRI, and a laminectomy was performed.
There was no hematoma, but a cyst was found under the subarachnoid space. Her neurologic symptoms partially improved over 6 months. We reviewed the complications of epidural anesthesia and arachnoid cysts.

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