Spinal cord injury often leads to central neuropathic pain syndromes, such as allodynic and hyperalgesic behaviors. Electrophysiologically, spinal dorsal horn neurons show enhanced activity to non-noxious and noxious stimuli as well as increased spontaneous activity following spinal cord injury, which often called hyperexcitability or central sensitization. Under hyperexcitable states, spinal neurons lose their ability of discrimination and encoding somatosensory information followed by abnormal somatosensory recognition to non-noxious and noxious stimuli. In the present review, we summarize a variety of pathophysiological mechanisms of neuronal hyperexcitability for treating or preventing central neuropathic pain syndrome following spinal cord injury.
Animals ; Central Nervous System Sensitization ; Discrimination (Psychology) ; Neuralgia ; Neurons ; Posterior Horn Cells ; Rats ; Spinal Cord ; Spinal Cord Injuries

Spontaneous pain, allodynia and hyperalgesia are well known phenomena following peripheral nerve or tissue injury, and it is speculated that secondary hyperalgesia and allodynia, are generally thought to depend on a hyperexcitability (sensitization) of neurons in the dorsal horn. It is supposed that the sensitization may be due to various actions of neurotransmitters (SP, CGRP, excitatory amino acids) released from the primary afferent fibers. In this study, we examined effects of the iontophoretically applied SP and CGRP on the response to EAA receptor agonists (NMDA and non-NMDA) in the WDR dorsal horn neurones and see if the effects of SP or CGRP mimic the characteristic response pattern known in various pain models. The main results are summarized as follows: 1) SP specifically potentiated NMDA response. 2) CGRP non-specifically potentiated both NMDA and AMPA responses. Potentiation of NMDA response, however, was significantly greater than that of AMPA response. 3) 50% of SP applied cells and 15.8% of CGRP applied cells showed reciprocal changes(potentiation of NMDA response and suppression of AMPA response). These results are generally consistent with the sensitization characteristics in diverse pain models and suggests that the modulatory effects of SP and CGRP on NMDA and non-NMDA (AMPA) response are, at least in part, contribute to the development of sensitization in various pain models.
Animal ; Calcitonin Gene-Related Peptide/pharmacology* ; Calcitonin Gene-Related Peptide/administration & dosage ; Excitatory Amino Acid Agonists/pharmacology* ; Iontophoresis ; Male ; N-Methylaspartate/pharmacology ; Rats ; Rats, Sprague-Dawley ; Spinal Cord/physiology ; Spinal Cord/drug effects* ; Substance P/pharmacology* ; Substance P/administration & dosage ; alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid/pharmacology

The authors experienced 2 cases of medulloblastoma in which active hemorrhage occurred after external ventricular drainage(EVD). A 5 year-old girl suffered from cerebellar fit and brain CT scan showed severe hydrocephalus. So EVD was performed and the pressure was measured about 80 cm H2O. After a gradual reduction of EVD pressure for 15 minutes, fresh blood gushed out through the EVD catheter. The other case was a 7 year-old girl whose tumor bled after intraoperative EVD, just before dural incision. Both tumors were highly vascular in operative field. The first case was bed-ridden at 5 months after surgery and the second case was on postoperative chemotherapy in a good general condition with minimal neurological deficits. Previous reports in the literatures including 2 cases of hemorrhage associated with EVD in medulloblastoma were reviewed. The relatively high incidence of tumor hemorrhage in medulloblastoma and its detrimental influence on the outcome are emphasized.
Brain ; Catheters ; Child ; Child, Preschool ; Drainage* ; Drug Therapy ; Female ; Hemorrhage* ; Humans ; Hydrocephalus ; Incidence ; Medulloblastoma* ; Tomography, X-Ray Computed

BACKGROUND: Allodynia, hyperalgesia, and spontaneous pain are symptoms characterized by chronic central pain which was frequently observed following a spinal cord injury (SCI). However, the underlying mechanism has not been fully understood. This study was conducted to investigate whether the loss of the GABAergic system in the spinal dorsal horn was involved in the development of central pain following a spinal cord injury. METHODS: SCI was induced by a hemisection of the spinal cord at T13 in adult male Sprague-Dawley rats. Mechanical allodynia was tested by measuring paw withdrawal frequency in response to repeated applications of a von Frey hair to the plantar surface of the hind-paw. Single neuronal activity of the dorsal horn neurons (L4 L6) was recorded extracellularly using a carbon filament-filled glass microelectrode (2 4 MOhm). The drugs were intrathecally or topically administrated on the spinal surface for behavioral and electrophysiological experiments, respectively. RESULTS: After a left spinal hemisection at T13, behavioral signs of mechanical allodynia developed on both hind-paws and responsiveness of spinal dorsal horn neurons increased on both sides of the spinal dorsal horn. GABA receptor agonists including GABAA and GABAB receptor subtypes suppressed mechanical allodynia on both sides of hind-paws and decreased responsiveness of spinal dorsal horn neurons on both sides of spinal cord. CONCLUSIONS: These results indicate that a loss of the GABAergic system within the spinal cord plays a key role on the development of central pain following a spinal cord injury.
Adult ; Animals ; Baclofen ; Carbon ; GABA Agonists ; gamma-Aminobutyric Acid ; Glass ; Hair ; Horns ; Humans ; Hyperalgesia ; Male ; Microelectrodes ; Muscimol ; Neurons ; Posterior Horn Cells ; Rats, Sprague-Dawley ; Spinal Cord Injuries* ; Spinal Cord*

No abstract available.
Chordoma*

BACKGROUND: The present study was designed to examine the functional recovery following spinal cord injury (SCI) by adjusting the parameters of impact force and dwell-time using the Infinite Horizon (IH) impactor device. METHODS: Sprague-Dawley rats (225-240 g) were divided into eight injury groups based on force of injury (Kdyn) and dwell time (seconds), indicated as Force-Dwell time: 150-4, 150-3, 150-2, 150-1, 150-0, 200-0, 90-2 and sham controls, respectively. RESULTS: After T10 SCI, higher injury force produced greater spinal cord displacement (P < 0.05) and showed a significant correlation (r = 0.813) between the displacement and the force (P < 0.05). In neuropathic pain-like behavior, the percent of paw withdrawals scores in the hindpaw for the 150-4, 150-3, 150-2, 150-1 and the 200-0 injury groups were significantly lowered compared with sham controls (P < 0.05). The recovery of locomotion had a significant within-subjects effect of time (P < 0.05) and the 150-0 group had increased recovery compared to other groups (P < 0.05). In addition, the 200-0 and the 90-2 recovered significantly better than all the 150 kdyn impact groups that included a dwell-time (P < 0.05). In recovery of spontaneous bladder function, the 150-4 injury group took significantly longer recovery time whereas the 150-0 and the 90-2 groups had the shortest recovery times. CONCLUSIONS: The present study demonstrates SCI parameters optimize development of mechanical allodynia and other pathological outcomes.
Animals ; Blood-Brain Barrier ; Contusions* ; Hyperalgesia* ; Locomotion* ; Neuralgia ; Rats* ; Rats, Sprague-Dawley ; Spinal Cord ; Spinal Cord Injuries ; Urinary Bladder*

The aim of the present study is to examine the brainstem sites where the electrical stimulation produces a suppression of dorsal horn neuron responses of neuropathic rats. An experimental neuropathy was induced by a unilateral ligation of L5-L6 spinal nerves of rats. Ten to 15 days after surgery, the spinal cord was exposed and single-unit recording was made on wide dynamic range (WDR) neurons in the dorsal horn. Neuronal responses to mechanical stimuli applied to somatic receptive fields were examined to see if they were modulated by electrical stimulation of various brainstem sites. Electrical stimulation of periaqueductal gray (PAG), n. raphe magnus (RMg) or n. reticularis gigantocellularis (Gi) significantly suppressed responses of WDR neurons to both noxious and non-noxious stimuli. Electrical stimulation of other brainstem areas, such as locus coeruleus. (LC) and n. reticularis paragigantocellularis lateralis (LPGi), produced little or no suppression. Microinjection of morphine into PAG, RMg, or Gi also produced a suppression as similar pattern to the case of electrical stimulation, whereas morphine injection into LC or LPGi exerted no effects. The results suggest that PAG, NRM and Gi are the principle brainstem nuclei involved in the descending inhibitory systems responsible for the control of neuropathic pain. These systems are likely activated by endogenous opioids and exert their inhibitory effect by acting on WDR neurons in the spinal cord.
Analgesics, Opioid ; Animals ; Brain Stem* ; Electric Stimulation* ; Horns ; Ligation ; Locus Coeruleus ; Microinjections ; Models, Animal* ; Morphine ; Neuralgia* ; Neurons ; Periaqueductal Gray ; Posterior Horn Cells* ; Rats* ; Spinal Cord ; Spinal Nerves

INTRODUCTION: It has been reported that the survival of low-grade glioma patients depends upon the time of malignant transformation. The authors presents the clinical analysis of histologically proven trasformed gliomas. MATERIALS AND METHODS: A total 92 patients who were consecutively treated and histologically confirmed hemispheric low-grade gliomas between 1980 and 1998 were analyzed and followed. All cases meet the criteria of WHO glioma classification of grade II. RESULTS: The mean follow-up period was 73 months. Twenty two among 92 cases(24%) were histologically proven to be transformed into malignant ones. The mean time to transformation was 56 months. The 5-year and 10-year survival rates of the transformed group were 66% and 30% respectively and significantly different from the survival rates of the non-transformed group(p=0.0018). Among clinical factors at presentation, the initial tumor volume had a tendency to be larger in the transformed group than that of the non-transformed group and became significant when it was divided into more than 30cm3 or not(p=0.02). Among therapeutic factors, the extent of removal had no influence on the rate of malignant transformation. But postoperative radiation therapy were more frequently given to the pre-transformed group than the non-transformed group and the frequency was significantly different(p=0.02). CONCLUSIONS: The authors had found that the initial tumor volume and radiation therapy could be clinical prognostic factors for the malignant transformation of low-grade gliomas.
Classification ; Follow-Up Studies ; Glioma* ; Humans ; Survival Rate ; Tumor Burden

No abstract available.
Adult* ; Humans ; Treatment Outcome*

The result of microvascular decompression(MVD) in 105 consecutive cases is presented. The symptomatic vasculoneural compressions including tumor, vascular malformation, or aneurysm are excluded in this study group. The 41 patients with trigeminal neuralgia(TN) were all treated by posterior fossa exploration(PEE). Eighteen of them were treated with MVD only, another 14 with partial sensory rhizotomy(PSR) only, and in the other 9 patients, MVD and PSR were performed together. Sixty-twp of 64 hemifacial spasm(HFS) cases were treated succesfully with MVD via PFE. However in one case of which the offending vessel was not identified, neurolysis was carried out. The other case who had both TN and HFS, died due to intraoperative cardiac arrest. The result of operation was evaluated at one month after the operation. In TN, among thirty-nine(98%) patients who resulted in pain-improvement, 32(82%) experienced complete resolution of the pain, The rate complete pain-relief was higher in the 'MVD only group' than in 'group with PSR'. Among 62(94%) cases of HFS, 29(47%) patients obtained 'complete cure' and 'improvement-only' respectively ; only 4(6%) patients had no change of the spasm. The preoperative clinical characteristics, intraoperative surgical findings and postoperative outcomes were itemized and analyzed find out the prognostic factors. The our results are compared with others in the literature.
Aneurysm ; Decompression* ; Heart Arrest ; Hemifacial Spasm* ; Humans ; Microvascular Decompression Surgery ; Spasm ; Trigeminal Neuralgia* ; Vascular Malformations