Background Acne keloidalis nuchae (AKN) is a chronic scarring folliculitis with fibrotic papules on the occipital scalp. Its treatment is limited and unsatisfactory. Objectives To determine if targeted ultraviolet B (tUVB) phototherapy will (1) improve the clinical appearance of AKN and (2) induce extracellular matrix remodeling in affected lesions. Methods Eleven patients with AKN were enrolled in a prospective, randomized, split-scalp comparison study. One randomly selected side of the scalp was treated with tUVB up to three times weekly for eight weeks. After week 8, both sides were treated for eight additional weeks. Assessment included lesion counts in two 3×3 cm regions of interest (ROI), one on each side of the scalp (ROI-1: tUVB week 0–16, ROI-2: tUVB week 9–16), patient self-assessment, and analysis of MMP-1, MMP-9, TGF-β1, and Col1a1 mRNA expression by qRT-PCR. Results Before treatment, the mean lesion count was similar between tUVB-treated and untreated sides (14.8 vs. 15.0). After eight weeks of tUVB, the mean lesion count decreased significantly to 9.4±1.2 (P=0.03), with no change on the untreated side. With continued treatment, the mean lesion count in ROI-1 decreased further to 7±1.5 (P=0.04) after 16 weeks of tUVB. Conclusion Targeted UVB significantly improved clinical appearance of AKN, led to patient satisfaction, and was well tolerated.

Cross-frequency coupling has been shown to be functionally significant in cortical information processing, potentially serving as a mechanism for integrating functionally relevant regions in the brain. In this study, we evaluate the hypothesis that pain-related gamma oscillatory responses are coupled with low-frequency oscillations in the frontal lobe, amygdala and hippocampus, areas known to have roles in pain processing. We delivered painful laser pulses to random locations on the dorsal hand of five patients with uncontrolled epilepsy requiring depth electrode implantation for seizure monitoring. Two blocks of 40 laser stimulations were delivered to each subject and the pain-intensity was controlled at five in a 0–10 scale by adjusting the energy level of the laser pulses. Local-field-potentials (LFPs) were recorded through bilaterally implanted depth electrode contacts to study the oscillatory responses upon processing the painful laser stimulations. Our results show that painful laser stimulations enhanced low-gamma (LH, 40–70 Hz) and high-gamma (HG, 70–110 Hz) oscillatory responses in the amygdala and hippocampal regions on the right hemisphere and these gamma responses were significantly coupled with the phases of theta (4–7 Hz) and alpha (8–12 Hz) rhythms during pain processing. Given the roles of these deep brain structures in emotion, these findings suggest that the oscillatory responses in these regions may play a role in integrating the affective component of pain, which may contribute to our understanding of the mechanisms underlying the affective information processing in humans.

Gamma time–frequency responses (TFRs) induced by painful laser in the contralateral primary somatosensory (SI) cortex have been shown to correlate with perceived pain-intensity in human. Given the functional roles of gamma TFRs in the cortical spaces, it remains unclear whether such a relationship is sustained for other brain regions where the laser-evoked potentials (LEPs) are presented. In this study, we delivered the painful laser pluses at random pain-intensity levels (i.e. strong, medium and weak) in a single train to the dorsal hand of six patients with uncontrolled epilepsy. The laser stimulus produced a painful pinprick sensation by activating nociceptors located in the superficial layers of the skin. For each patient, arrays of >64 subdural electrodes were implanted directly covering the contralateral SI, parasylvian (PS) and medial frontal (MF) cortices to study the stimulus related gamma (TFRs) in the neocortex. In addition, using the same stimulation paradigm, the modality specificity of gamma TFRs was further examined by applying innocuous vibrotactile stimuli to the same regions of the dorsal hand in a separated group of five patients. Our results showed that gamma TFRs are not modality specific, but the largest gamma TFRs were consistently found within the SI region and noxious laser elicited significantly stronger gamma TFRs than innocuous nonpainful vibratory stimuli. Furthermore, stronger pain induced stronger gamma TFRs in the cortices of SI (r = 0.4, p < 0.001) and PS (r = 0.29, p = 0.005). Given that potentially harmful noxious stimulus would automatically capture greater attention than the innocuous ones, our results support the hypothesis that the degree of SI and PS gamma TFRs is associated with an attentional drive provoked by painful stimuli.