ABSTRACT Background: New-onset chronic pain has been acknowledged as part of the post-COVID-19 condition. However, available fine-grained data about its clinical phenotype, trajectories and main associated characteristics remain scarce. We described the distinct temporal evolutions of post-COVID-19 pain and their epidemiological and phenotypical features. Methods: A prospective cross-sectional study enrolled post-COVID-19 condition patients (i.e. who had persisting COVID-19-related symptoms over 30 days since their first positive laboratory test), whose COVID-19 diagnosis had been supported by RT-PCR of oral/nasopharyngeal swab or serology. They underwent in-person evaluations with a structured interview, pain and quality-of-life-related questionnaires and thorough physical examination. Chronic pain (CP) and probable neuropathic pain (NP) were defined according to IASP criteria. Results: The present study included 226 individuals, 177 (78.3 %) of whom presented over 3 months since their first COVID-19 symptom. New-onset pain occurred in 170 (75.2 %) participants and was chronic in 116 (68.2 %). A chronic course was associated with COVID-19-related hospitalization, new-onset fatigue, lower cognitive performance, motor and thermal sensory deficits, mood and sleep impairments and overall lower quality-of-life levels. Probable NP occurred in only 7.6 % new-onset pain patients, and was associated with pain chronification, new-onset fatigue, motor and thermal sensory deficits, mechanical allodynia and lower rates of SARS-CoV-2 vaccination. Previous CP was reported by 86 (38.1 %) individuals and had aggravated after the infection in 66 (76.7 %) of them, which was associated with orthostatic hypotension. Conclusions: Post-COVID pain phenomena follow different paths, which are associated with specific clinical and epidemiological features, and possibly distinct underlying mechanisms, prognostic and therapeutic implications. Significance: COVID-19-related pain usually follows a chronic course and is non-neuropathic. Its possible courses and phenotypes are associated with distinct clinical and epidemiological features. This suggests differing underlying mechnisms, which may have significant prognostic and therapeutic implications.

RESUMEN Antecedentes: El dolor crónico de nueva aparición se considera que forma parte de la condición o afección post-COVID-19. Sin embargo, los datos detallados existentes sobre el fenotipo clínico, las trayectorias y las principales características asociadas siguen siendo escasos. Describimos las distintas evoluciones temporales del dolor post-COVID-19 y sus rasgos epidemiológicos y fenotípicos. Métodos: Estudio prospectivo y transversal de pacientes con afección post-COVID-19 (es decir, con síntomas persistentes relacionados con la COVID-19 durante 30 días desde la primera prueba positiva de laboratorio) cuyo diagnóstico de COVID-19 estuviera basado en la RT-PCR de un frotis oral/nasofaríngeo o una serología. Se sometieron a evaluaciones presenciales mediante una entrevista estructurada, cuestionarios de dolor y calidad de vida y una exploración física exhaustiva. El dolor crónico (DC) y el dolor neuropático (DN) probablemente se definieron conforme a los criterios IASP. Resultados: El presente estudio incluyó 226 individuos, 177 (78,3 %) de los cuales se presentaron pasados más de 3 meses desde el primer síntoma de COVID-19. Tenían dolor de nueva aparición 170 (75,2 %) de los participantes y dolor crónico 116 (68,2 %). El curso crónico se asociaba a hospitalización por COVID-19, fatiga de nueva aparición, menor rendimiento cognitivo, déficits motores y sensitivos térmicos, alteraciones del ánimo y el sueño, y niveles generalmente inferiores de calidad de vida. El DN probable afectaba a solo el 7,6 % de los pacientes con dolor de nueva aparición y se asociaba a cronificación del dolor, fatiga de nueva aparición, déficits motores y de sensación térmica, alodinia mecánica y tasas menores de vacunación frente al SARS-CoV-2. Referían DC previo 86 (38,1 %) individuos, y este había empeorado tras la infección en 66 (76,7 %) de ellos, lo que se asociaba a hipotensión ortostática. Conclusiones: Los fenómenos dolorosos post-COVID siguen diferentes trayectorias que se asocian a rasgos clínicos y epidemiológicos específicos, y posiblemente a distintos mecanismos de base y diferentes implicaciones pronósticas y terapéuticas. Significado: El dolor relacionado con la COVID-19 sigue normalmente un curso crónico y no es neuropático. Los posibles cursos y fenotipos se asocian a rasgos clínicos y epidemiológicos distintos. Esto sugiere que los mecanismos de base difieren, lo que podría tener implicaciones pronósticas y terapéuticas importantes.

RESUMO. A capacidade de repetir palavras é quase sempre preservada na afasia talâmica. A fisiopatologia da afasia talâmica assim como a da preservação da repetição não são totalmente compreendidas. Em um caso de afasia grave com repetição preservada após hemorragia talâmica esquerda, a RM revelou lesão talâmica esquerda e perda de anisotropia fracionada no centro semioval. O FDG-PET revelou hipometabolismo grave no hemisfério cerebral esquerdo, exceto nos giros temporais superiores e transversos, fissura calcarina e regiões frontopares. A função sensorial primária pode ser menos funcionalmente dependente das conexões talâmicas do que as áreas heteromodais e paralímbicas, que têm conexões com vários núcleos talâmicos. O hipometabolismo cortical extenso devido à diasquise pode ter sido responsável pela gravidade da afasia, enquanto a redução menos severa do metabolismo nos giros temporal superior e transverso, e também, embora menos evidente, na área de Broca, poderia explicar a preservação da repetição.

ABSTRACT. The ability to repeat words is almost always preserved in thalamic aphasia. The pathophysiology of both thalamic aphasia and preservation of repetition are not fully understood. In a case of severe aphasia with preserved repetition after a left thalamic hemorrhage, MRI disclosed left thalamic lesion and loss of fractional anisotropy in the left centrum semiovale. FDG-PET showed severe hypometabolism in the left cerebral hemisphere, except for superior and transverse temporal gyri, calcarine fissure and frontopolar regions. Primary sensory function may be less functionally dependent on thalamic connections than heteromodal and paralimbic areas, which have connections with several thalamic nuclei. The extensive cortical hypometabolism due to diaschisis may have been responsible for the severity of the aphasia, whereas the less severe reduction of metabolism in the superior and transverse temporal gyri, and also, albeit less evident, in Broca’s area, might explain the preservation of repetition.