Laser heat stimulation of tiny skin areas adds valuable information to quantitative sensory testing in postherpetic neuralgia
Franz M et al. – Laser stimulation proved more sensitive and specific in detecting thermal sensory abnormalities in the neuralgia–affected skin, as well as in the control skin, than any single thermal parameter of thermode stimulation. Thus, laser stimulation of tiny skin areas might be a useful diagnostic tool for small–fiber dysfunction.Methods
- Authors contrasted detection rate of laser stimuli with 5 thermal parameters (thresholds of cold/warm detection, cold/heat pain, and sensory limen) of quantitative sensory testing.
- Sixteen patients diagnosed with unilateral postherpetic neuralgia and 16 age– and gender–matched healthy control subjects were tested.
- Quantitative sensory testing and laser stimulation of tiny skin areas were performed in the neuralgia–affected skin and in the contralateral homologue of the neuralgia–free body side.
- Across the 5 thermal parameters of thermode stimulation, only one parameter (warm detection threshold) revealed sensory abnormalities (thermal hypoesthesia to warm stimuli) in the neuralgia–affected skin area of patients but not in the contralateral area, as compared to the control group.
- In contrast, patients perceived significantly less laser stimuli both in the affected skin and in the contralateral skin compared to controls.