Pain medicine : the official journal of the American Academy of Pain Medicine
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Review Case Reports
Intravenous Ketamine for Rapid Opioid Dose Reduction, Reversal of Opioid-Induced Neurotoxicity, and Pain Control in Terminal Care: Case Report and Literature Review.
We report a case of opioid-induced neurotoxicity (OIN) in an actively dying hospice patient, its reversal and improved analgesia that followed opioid dosage reduction made possible after addition of IV ketamine. We briefly review the diagnosis and treatment of OIN. ⋯ OIN should be considered as an etiology of CNS dysfunction occurring with prolonged, high-dose opioid therapy. This case highlights the opioid-sparing and analgesic properties of low-dose ketamine, allowing reversal of OIN in the home hospice setting.
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Dry eye is a multi-factorial disorder that manifests with painful ocular symptoms and visual disturbances, which can only be partly attributed to tear dysfunction. This disorder may also involve neuroplasticity in response to neuronal injury. This review will emphasize the key characteristics of dry eye pain and its pathologic mechanisms, making the argument that a subset of dry eye represents a neuropathic pain disorder of the eye, more appropriately called "burning eye syndrome." ⋯ Dry eye is becoming a major health concern due to its increasing incidence, significant morbidity, and economic burden. Recent evidence suggests that a subset of dry eye may be better represented as a chronic neuropathic pain disorder due to its features of dysesthesia, spontaneous pain, allodynia, and hyperalgesia. Future therapies targeted at the underlying neuroplasticity may yield improved efficacy for patients with this subset of dry eye, which we term "burning eye syndrome."
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Randomized Controlled Trial
Transcranial Direct Current Stimulation (tDCS) Targeting Left Dorsolateral Prefrontal Cortex Modulates Task-Induced Acute Pain in Healthy Volunteers.
Current chronic pain treatments target nociception rather than affective "suffering" and its associated functional and psychiatric comorbidities. The left dorsolateral prefrontal cortex (DLPFC) has been implicated in affective, cognitive, and attentional aspects of pain and is a primary target of neuromodulation for affective disorders. Transcranial direct current stimulation (tDCS) can non-invasively modulate cortical activity. The present study tests whether anodal tDCS targeting the left DLPFC will increase tolerability of acute painful stimuli vs cathodal tDCS. ⋯ Although our results do not suggest that polarity of tDCS targeting the left DLPFC differentially modulates the tolerability of CP- and BH-related pain distress in healthy volunteers, there was a significant effect on DVPRS pain ratings. This contrasts with our previous findings that tDCS targeting the left dorsal anterior cingulate cortex showed a trend toward higher mean CP tolerance with cathodal vs anodal stimulation. The present results may suggest tDCS-related effects on nociception or DLPFC-mediated attention, or preferential modulation of the affective valence of pain as captured by the DVPRS. Sham-controlled clinical studies are needed.
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Randomized Controlled Trial
Impact of Data Imputation Methodology on Pain Assessment over 24 Hours in a Randomized, Placebo-Controlled Study of Gabapentin Enacarbil in Patients with Neuropathic Pain Associated with Postherpetic Neuralgia.
To assess the impact of gabapentin enacarbil on primary and secondary pain endpoints using three data imputation methodologies in a randomized phase II study of adult patients with postherpetic neuralgia. ⋯ Gabapentin enacarbil (1,200 mg, 2,400 mg, and 3,600 mg) was effective and well tolerated in patients with postherpetic neuralgia compared with placebo, as confirmed by three different and robust statistical methodologies.