Clinical and pathogenetic phenotypes of chronic postamputation pain

Objective. To develop an algorithm for identifying clinical and pathophysiological phenotypes of chronic postamputation pain. Material and methods. A questionnaire was developed for examination of patients. This questionnaire includes sections for collecting anamnestic data, entering neurological examination data. Pain intensity was assessed according to numeric rating scale (NRS). The following questionnaires and scales were used for psychometric examination: the Hospital Anxiety and Depression Scale (HADS), the Mississippi Scale for Combat-Related Posttraumatic Stress Disorder, the Pain Catastrophizing Scale (PCS), and the Central Sensitization Inventory (CSI). To differentiate nociceptive and neuropathic pain in the stump, a questionnaire for diagnosis of neuropathic pain (DN4) was used. The Second Short Form of the McGill Pain Questionnaire (SF-MPQ-2) was used to accurately determine descriptors of postamputation pain and intensity of symptoms. The “Budapest Criteria” adapted by the International Association for the Study of Pain (2021) were used to make the diagnosis of complex regional pain syndrome. Results. Eighty-two patients were examined. Of these, 70 (85%) patients had phantom limb pain, 40 (49%) — stump pain, 32 (39%) — combination of stump pain and phantom pain syndrome, 2 (2%) — complex regional pain syndrome according to the “Budapest Criteria”. Other 19 (23%) patients had neuroma. Conclusion. The mechanism of formation and maintenance of chronic postamputation pain is extremely complex and involves various levels of somatosensory system. This causes various pain syndromes and makes necessary to determine clinical phenotypes of postamputation pain. This is important to personalize treatment approaches taking into account pathogenetic features of pain syndrome. Original algorithm makes it possible to identify postamputation pain phenotypes in clinical practice.