Table 4.

Clinical Factors Implicated in the Differential Diagnosis of OIH

Clinical factor	Clinical finding
Temporal summation of second pain	Exacerbated (QST)
Pain threshold (cold or heat)	Decreased (QST) - particularly heat pain
Pain tolerance (cold or heat)	Decreased (QST)
Supra-threshold stimulation	Decreased duration of tolerance (QST)
Average opioid dose	≥ 75 mg daily morphine equivalent dose
Duration of opioid therapy	≥ 3 months
Opioid dose escalation	Limited improvement or normalization on QST responses
Opioid dose reduction	Improved opioid analgesia [38]
Pain quality	Burning, diffuse pain, and spontaneous pain similar to those seen with neuropathic pain
Pain location	At and/or beyond the dermatome distribution of a pre-existing pain condition
Pain intensity	Similar or greater than pre-existing pain
Opioid type to be considered	Short-acting vs. long acting; methadone versus other opioid analgesics
Gender	Female vs. male?