Symptoms Evolve With Pathophysiology Over Time
In the study, patients with painful TTR-FAP complained of ongoing burning pain sensations, pain aggravation at rest, paroxysmal pain, or provoked pain despite treatment with analgesic drugs.
However, the symptomatic presentation of pain evolved with disease duration and severity of small-fiber lesions. The intensity of ongoing burning pain sensation decreased over time, while the intensity of electric shock and stabbing sensations increased. The evolution of disease was also accompanied by a more altered thermal sensitivity.
“Our study showed that when a neuropathy is painful, the progression of the disease — the progressive loss of small or large sensory nerve fibers — will impact the clinical features and symptoms of pain,” Dr. Lefaucheur explained.
According to the authors, the pattern suggests the presence of multiple pathophysiologic mechanisms in TTR-FAP pain.
In early disease, peripheral sensitization of small-diameter nociceptive fibers in early disease could be at the origin of burning pain sensation, while central sensitization could lead to pain aggravation at rest.
Central sensitization, driven by abnormal activities concerning the relatively spared large-diameter nonnociceptive fibers, could be at the origin of paroxysmal pain and dynamic mechanical allodynia, when small fibers are more severely impaired.
“Further research is needed to investigate various mechanisms, including function of nociceptors and axons of small sensory fibers, or central processes of pain integration and control at both spinal and encephalic levels,” Dr. Lefaucheur concluded.
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