The Synergistic Effect of Intrathecally Administered Dexmedetomidine and Ketorolac on Mechanical Allodynia in Rats with Spinal Nerve Ligation / 고신대학교의과대학학술지

OBJECTIVES: This research was carried out to identify the synergistic effect of dexmedetomidine and ketorolac on neuropathic pain alleviation. METHODS: The anti-allodynic effect of intrathecal dexmedetomidine and ketorolac was investigated in rats after L5 spinal nerve ligation (SNL). Mechanical allodynia was assessed using Von Frey filaments. Every day for 3 consecutive days, beginning on the 10th day after SNL, behavioral tests were carried out at 1, 2, and 4 hr after drug injection. RESULTS: Significant increases in ipsilateral paw withdrawal thresholds (PWTs) were observed 1, 2, and 4 hr after drug injection in the groups of rats which received intrathecal injection of either dexmedetomidine (group D) or ketorolac (group K), compared to group S (P < 0.05). And group DK, which received simultaneous intrathecal injection of both dexmedetomidine and ketorolac, showed statistically significantly higher ipsilateral PWTs than groups D and K, which received only one of them (P < 0.05). CONCLUSIONS: The results of this research demonstrated the anti-allodynic effect of dexmedetomidine and ketorolac on neuropathic pain induced by SNL in rats. They also suggest that synergistic analgesia can be induced by the simultaneous injection of dexmedetomidine and ketorolac, and that combination therapy is an effective approach to treating chronic neuropathic pain syndrome.

Delayed Pneumocephalus Following Fluoroscopy Guided Cervical Interlaminar Epidural Steroid Injection: A Rare Complication and Anatomical Considerations

Cervical epidural steroid injection is indicated for radicular symptoms with or without axial neck pain. Complications are rare but can be serious. Here, we report the case of a 54-year-old man with cervical radicular pain who was treated with cervical epidural steroid injection. Injection was administered twice under fluoroscopic guidance with the loss-of-resistance technique using air to confirm the epidural space. After the second procedure, the patient complained of severe persistent headache and was diagnosed with pneumocephalus on brain computed tomography. The patient returned home without any neurological complication, after a few days of conservative treatment. Though, a fluoroscopic guidance cervical epidural injection is also known to diminish the risk of complications. Physicians should always keep in mind that it does not guarantee safety, particularly in the cervical region, related to its anatomical considerations.

Chronic Administration of Monosodium Glutamate under Chronic Variable Stress Impaired Hypothalamic-Pituitary-Adrenal Axis Function in Rats

The hypothalamic-pituitary-adrenal (HPA) axis is the primary endocrine system to respond to stress. The HPA axis may be affected by increased level of corticotrophin-releasing factors under chronic stress and by chronic administration of monosodium glutamate (MSG). The purpose of this study was to investigate whether chronic MSG administration aggravates chronic variable stress (CVS)-induced behavioral and hormonal changes. Twenty-four adult male Sprague-Dawley rats, weighing 200~220 g, were divided into 4 groups as follows: water administration (CON), MSG (3 g/kg) administration (MSG), CVS, and CVS with MSG (3 g/kg) administration (CVS+MSG). In addition, for the purpose of comparing the effect on plasma corticosterone levels between chronic stress and daily care or acute stress, 2 groups were added at the end of the experiment; the 2 new groups were as follows: naive mice (n=7) and mice exposed to restraint stress for 2 h just before decapitation (A-Str, n=7). In an open field test performed after the experiment, the CVS+MSG group significant decrease in activity. The increase in relative adrenal weights in the CVS and CVS+MSG group was significantly greater than those in the CON and/or MSG groups. In spite of the increase in the relative adrenal weight, there was a significant decrease in the plasma corticosterone levels in the CVS+MSG group as compared to all other groups, except the naive group. These results suggest that impaired HPA axis function as well as the decrease in the behavioral activity in adult rats can be induced by chronic MSG administration under CVS rather than CVS alone.