Peripheral and central pathogenesis of postherpetic neuralgia.

BACKGROUND: Postherpetic neuralgia (PHN) is a classic chronic condition with multiple signs of peripheral and central neuropathy. Unfortunately, the pathogenesis of PHN is not well defined, limiting clinical treatment and disease management. OBJECTIVE: To describe the peripheral and central pathological axes of PHN, including peripheral nerve injury, inflammation induction, central nervous system sensitization, and brain functional and structural network activity. METHODS: A bibliographic survey was carried out, selecting relevant articles that evaluated the characterization of the pathogenesis of PHN, including peripheral and central pathological axes. RESULTS: Currently, due to the complexity of the pathophysiological mechanisms of PHN and the incomplete understanding of the exact mechanism of neuralgia. CONCLUSION: It is essential to conduct in-depth research to clarify the origins of PHN pathogenesis and explore effective and comprehensive therapies for PHN.

Relationship Between Patient-reported Outcome Measures and Accelerometer-measured Physical Activity and Sleep in Patients With Postherpetic Neuralgia.

OBJECTIVE: Available treatment for chronic neuropathic pain is still limited, and the positive effects are modest. Thus, clinicians aim to improve activity and quality of life despite pain. The objective monitoring of activity is attracting attention in chronic pain assessments. Therefore, we objectively evaluated daytime activity and sleep in patients with postherpetic neuralgia (PHN), using actigraphy to determine risk factors for decreased activity. METHODS: Participants with PHN wore an actigraph (a wristwatch-like accelerometer) on the nondominant hand. The actigraph measured day-time activity and sleep, which were compared with participant-reported subjective pain and sleep assessments. RESULTS: Fifty-four individuals with PHN who visited our outpatient clinic completed questionnaires and a week of actigraph monitoring. Subjective scores of pain intensity, neuropathic pain, disability in daily life, pain-catastrophizing thoughts, and insomnia were all well correlated. However, the actigraph-monitored activity levels, using 2 equations, and sleep quality were not associated with any pain or sleep-related subjective scores. CONCLUSION: The discrepancy between the subjective and objective scores in this study may be due to (1) features of PHN, an archetype of peripheral neuropathic pain affecting no motor nerves, (2) actigraph measurement limitations regarding the sedentary life of the elderly, or (3) activity misperception, a new proposition explaining the discrepancy between subjective and objective measures of activity, similar to the sleep state misperception. In patients with PHN, high pain intensity may be reported in those with highly maintained activity, in which treatment must be selected cautiously to prevent interruption of their physical abilities.

Toxina botulínica no tratamento da neuralgia pós herpética: um desafio terapêutico / Botulinum toxin in the treatment of postherpetic neuralgia: a therapeutic challenge

A neuralgia pós-herpética (NPH) é a principal complicação do herpes zoster. Caracteriza-se por dor que persiste por mais de três meses após o episódio de reativação do vírus varicela zoster, com impacto importante na qualidade de vida. A terapia de primeira linha da NPH consiste nos antidepressivos tricíclicos, inibidores de recaptação de serotonina e noradrenalina, além dos anticonvulsionantes pregabalina e gabapentina. Nos casos refratários, o uso subcutâneo da toxina botulínica A (TXB-A), é uma possibilidade terapêutica. A TXB-A, além de inibir a exocitose da acetilcolina na fenda sináptica da junção neuromuscular, também diminui a liberação de outros mediadores como glutamato, substância P e peptídeo relacionado à calcitonina, responsáveis pela ativação de nociceptores. Neste estudo, foram analisados os prontuários de seis pacientes com NPH, tratados com TXB-A concomitantemente à terapia padrão, no ambulatório de Dermatologia Geral do Hospital do Servidor Público Municipal de São Paulo, com o objetivo de avaliar se houve melhora da dor, através da comparação dos valores da escala visual de dor (EVA). Palavras-chave: Neuralgia pós herpética. Toxinas Botulínicas Tipo A. Herpes zoster.