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Biomedical subjects

Timothy J Ness

Publications and source records attributed to Timothy J Ness.

27 records · Page 2Linked to original sources
PubMed2003

Use of topiramate for spinal cord injury-related pain.

BACKGROUND: Pain following spinal cord injury (SCI) has proved difficult to treat. Although the use of antiepileptic drugs to treat SCI-related pain has been studied previously, topiramate has not been investigated in this population. Our recent experience suggests that topiramate may be efficacious in the treatment of SCI-related pain. METHOD: Case Studies Findings: This report presents the clinical histories of two people with pain following SCI who reported beneficial effects of treatment with the new antiepileptic drug topiramate, even after failing treatment with standard analgesic medications. Topiramate was well tolerated in these patients. CONCLUSION: For post-SCI pain, topiramate appears to be an effective treatment in some patients. Based on the present anecdotal findings, larger controlled studies comparing topiramate with standard treatment for SCI-related pain are warranted.

Adult↗
PubMed2002

Spinal neurophysiologic correlates of the analgesic actions of intravesical dimethyl sulfoxide and capsaicin in the rat.

Peripheral analgesia produced by the intravesical instillation of dimethyl sulphoxide (DMSO) and capsaicin has been used to treat visceral pain originating in the urinary bladder. The present study sought to determine the neurophysiologic consequences of the intravesical instillation of these compounds by measuring spinal neuronal responses evoked by urinary bladder distension (UBD) in the rat. Subjects were spinally transected, decerebrate female Sprague-Dawley rats. The effect of 0.5 mL of solution of 10% or 50% DMSO, 100 micromol/L capsaicin, or the same volume of saline instilled into the bladder on excitatory neuronal responses to UBD was studied by using single-unit extracellular recordings of L6-S2 dorsal horn spinal cord neurons. Fifty-six dorsal horn neurons that were excited by UBD in a graded fashion were identified. All neurons were also excited by noxious or non-noxious cutaneous stimuli. Two hours after intravesical instillation, solutions of 50% DMSO or 100 micromol/L of capsaicin produced a reduction of the slope of stimulus-response functions for neuronal activity evoked by graded UBD. These data support a local effect of intravesical 50% DMSO or capsaicin and suggest the use of this model to study novel peripheral treatment strategies for bladder pain.

Journal Article↗
PubMed2002

Ketamine, an N-methyl-D-aspartate receptor antagonist, inhibits the reflex responses to distension of the rat urinary bladder.

BACKGROUND: Ketamine is analgesic in experimental and clinical studies of inflammatory, neuropathic, and postoperative pain. Its role in the treatment of visceral pain is less known. The authors investigated the effect and site of action of ketamine on reflex responses evoked by urinary bladder distension (UBD). The effects of other clinically available N-methyl-d-aspartate (NMDA) receptor antagonists on these responses were also studied. METHODS: The effect of intravenous ketamine (1, 3, and 10 mg/kg), dextromethorphan (5 mg/kg), and memantine (16 mg/kg) on mean arterial pressure changes (Delta MAP) and abdominal electromyographic activity (EMG) evoked by UBD was measured in anesthetized rats. Ketamine was also administered intravesically and intrathecally and its effect on Delta MAP and EMG responses to UBD recorded. The effect of pretreatment with intravenous ketamine on these responses was also assessed. RESULTS: The Delta MAP and EMG responses to UBD were reduced in a dose-dependent fashion by ketamine. Memantine and dextromethorphan also inhibited these responses. Ketamine administered intrathecally produced marked inhibition of Delta MAP and EMG responses to UBD. Pretreatment with ketamine only transiently reduced the vigor of responses to UBD. CONCLUSIONS: Ketamine inhibited, in a dose-dependent fashion, the Delta MAP and EMG responses to UBD, an effect likely caused by actions within the spinal cord. Similar inhibition observed with systemic dextromethorphan and memantine treatments suggests that the analgesic effect of ketamine is caused by antagonism of the NMDA receptor. Pretreatment with ketamine did not have a preventive effect in this model of bladder nociception.

Animals↗
PubMed2002

Ketamine, an N-methyl-D-aspartate receptor antagonist, inhibits the spinal neuronal responses to distension of the rat urinary bladder.

BACKGROUND: The effect of ketamine as a treatment of visceral pain is not known. The current study investigated the effect of ketamine on spinal dorsal horn neurons excited by urinary bladder distension (UBD). The effect of other clinically available N-methyl-D-aspartate receptor antagonists on these responses was also studied. METHODS: Extracellular recordings of neurons located in the L6-S2 spinal dorsal horn of cervical spinal cord-transected, decerebrate female rats were obtained. Cutaneous receptive fields of neuronal units excited by UBD were characterized for responses to segmental noxious and nonnoxious stimuli. Nonsegmental noxious stimuli were also applied, and neurons were classified as type I (inhibited) and type II (noninhibited) by the stimulus. The effect of intravenous ketamine (1, 3, and 10 mg/kg), dextromethorphan (5 mg/kg), and memantine (16 mg/kg) on neuronal responses of these units was measured. RESULTS: Spontaneous and evoked neuronal activity to UBD was reduced in a dose-dependent fashion by ketamine. Responses to nonnoxious cutaneous stimuli were also significantly reduced after treatment. Dextromethorphan inhibited neuronal activity evoked by UBD in type I neurons. A similar selective effect of treatment on type I versus type II neurons was observed after intravenous ketamine and memantine. CONCLUSIONS: Intravenous ketamine produces dose-dependent inhibition of the spinal cord neuronal responses evoked by UBD. All three N-methyl-D-aspartate receptor antagonists showed selective effects on spinal cord neurons subject to counterirritation. This neurophysiologic evidence supports a spinally mediated analgesic effect of ketamine in this model of urinary bladder nociception, an effect likely caused by N-methyl-D-aspartate receptor antagonism.

Animals↗
PubMed1998

A case of spinal cord injury-related pain with baseline rCBF brain SPECT imaging and beneficial response to gabapentin.

Central pain following spinal cord injury is poorly understood, and is often resistant to conventional pain therapy regimens. We describe an individual with paraplegia who for many years experienced rapidly fluctuating, severe, unilateral pain below the level of his lesion. Prior to the initiation of pharmacological treatment, regional cerebral blood flow (rCBF) was measured during PAIN and NON-PAIN states using single photon emission computed tomography (SPECT). When experiencing pain, the subject had increased anterior cingulate gyrus blood flow, increased thalamic blood flow bilaterally and increased somatosensory cortex blood flow contralaterally but decreased caudate blood flow bilaterally. The subject's subsequent clinical course included a trial of gabapentin which produced a substantial reduction in frequency and average intensity of his episodic pain and which has been maintained for almost 2 years. This case demonstrates the correspondence between rCBF and pain associated with spinal cord injury and also suggests the potential utility of gabapentin for treatment of this central pain state.

Acetates↗
PubMedDate not supplied

Which spinal cutaneous nociceptive neurons are inhibited by intravenous lidocaine in the rat?

BACKGROUND AND AIMS: Intravenous lidocaine (IVL) produces analgesia in multiple painful disorders. The neurophysiological effects of IVL are not well defined, but studies in visceral nociceptive systems have shown that IVL has differential effects on subgroups of spinal neurons. The present study determined whether a similar differential effect of IVL occurs in spinal neurons excited by noxious cutaneous stimuli. METHODS: In decerebrate, cervical spinal cord-transected rats, the lumbosacral spinal cord was exposed by a laminectomy. Single-unit recordings were made of dorsal horn neurons excited by noxious cutaneous stimuli. Each neuron's response to noxious (pinch) and nonnoxious (brush) cutaneous stimuli were determined and the effect of a counterirritation stimulus (noxious skin pinch presented in the upper body) on spontaneous activity quantified. In a subset of neurons, sequential doses of IVL were administered, and responses of each neuron to repeated 50 degrees C heating of the hindpaw/tail were determined. RESULTS: IVL dose-dependently inhibited neurons excited by heating of the hindpaw/tail. IVL produced significantly greater inhibition of both spontaneous and heat-evoked activity in neurons that did not show counterirritation effects when compared with those neurons that did show counterirritation effects. Standard classification of neurons as wide-dynamic range or nociceptive-specific was less predictive of the IVL effect. CONCLUSIONS: IVL had differential inhibitory effects on 2 spinal cutaneous nociceptive neuron populations. Other drugs could also have differential effects on sensory pathways, suggesting a mechanism whereby certain drugs differentially affect different types of pain.

Anesthetics, Local↗
PubMedDate not supplied

Hypoxia following interscalene block.

BACKGROUND AND OBJECTIVES: Interscalene brachial plexus block is often used for surgeries involving the shoulder and upper arm. Known complications include phrenic nerve paralysis, intravascular injection, and cervical epidural block. We report a patient who developed acute hypoxia immediately following this block, presumably secondary to an acute pulmonary thromboembolus (PTE) coupled with phrenic nerve paralysis. CASE REPORT: A 43-year-old man with end-stage renal disease secondary to hypertension was scheduled for primary placement of a left upper extremity arteriovenous fistula. A technically unremarkable interscalene brachial plexus block was performed using a 22-gauge regional block needle and 35 mL of 1.5% mepivacaine. Immediately following injection, the patient's oxygen saturation decreased from 99% to 85%, and he complained of chest pain and shortness of breath and developed hemoptysis. Workup revealed an elevated hemidiaphragm, but no pneumothorax or evidence of local trauma. A spiral computed tomogram (CT) suggested acute pulmonary thromboemboli as the etiology of the hypoxia and hemoptysis, although the diagnosis was uncertain. CONCLUSIONS: This case report suggests that manipulations and vasodilation related to an interscalene block may have facilitated the dislodgement of a pre-existing upper extremity thrombus.

Acute Disease↗
PubMedDate not supplied

Use of compounded topical analgesics--results of an Internet survey.

Topically applied single or multiagent analgesics compounded by specialty pharmacies are utilized by an unknown number of pain clinicians to unknown effect. To assess the use and perceived efficacy of these agents, an e-mail survey of members of the American Society of Regional Anesthesia and Pain Medicine was performed. Response rate was low, but identified use of compounded topical agents throughout the United States. Of the 120 clinicians responding, 27% (n = 32) reported that they prescribed compounded topical analgesics containing 1 to 5 agents (mean + SEM; 2.6 +/- 0.2) in their practice 3.5 +/- 0.6 times per month. Use of 36 different agents of varying concentrations was reported. These clinicians perceived that 43% +/- 4% of treated patients responded favorably to the topical agents with an average of 47% +/- 3% pain relief and few side effects. Despite favorable reports of benefit, most clinicians perceived use of such compounded agents in their regions to generally be "little or none."

Administration, Topical↗