# POST-POLIO SYNDROME – SOMATOSENSORY DYSFUNCTION AND ITS RELATION TO PAIN: A PILOT STUDY WITH QUANTITATIVE SENSORY TESTING

## TL;DR

This pilot study explores sensory dysfunction in post-polio syndrome patients and finds signs of increased mechanical pain sensitivity, possibly linked to chronic pain.

## Contribution

The study is the first to use Quantitative Sensory Testing to characterize somatosensory dysfunction in post-polio syndrome.

## Key findings

- Sensory profiles showed increased sensory aberrations, especially in mechanical pain thresholds.
- Five out of six patients had significant deviations from reference data in mechanical pain thresholds.
- No clear differences were found between more and less affected extremities, suggesting generalized dysfunction.

## Abstract

To explore and characterize somatosensory dysfunction in patients with post-polio syndrome and chronic pain, by conducting examinations with Quantitative Sensory Testing.

A cross-sectional, descriptive, pilot study conducted during 1 month.

Six patients with previously established post-polio syndrome and related chronic pain.

All subjects underwent a neurological examination including neuromuscular function, bedside sensory testing, a thorough pain anamnesis, and pain drawing. Screening for neuropathic pain was done with 2 questionnaires. A comprehensive Quantitative Sensory Testing battery was conducted with z-score transformation of obtained data, enabling comparison with published reference values and the creation of sensory profiles, as well as comparison between the study site (more polio affected extremity) and internal control site (less affected extremity) for each patient.

Derived sensory profiles showed signs of increased prevalence of sensory aberrations compared with reference values, especially Mechanical Pain Thresholds, with significant deviation from reference data in 5 out of 6 patients. No obvious differences in sensory functions were seen between study sites and internal control sites.

Post-polio syndrome may be correlated with a mechanical hyperalgesia/allodynia and might be correlated to a somatosensory dysfunction. With lack of evident side-to-side differences, the possibility of a generalized dysfunction in the somatosensory system might be considered.

LAY ABSTRACT

A significant number of polio survivors develop post-polio syndrome later in life, a condition characterized by increased weakness, fatigue, and pain. As the polio virus affects only specific parts of the nervous system, typically the sensory signalling pathways do not become affected. However, there are some reports suggesting that these patients may more often suffer from disturbed sensory functions compared with otherwise healthy subjects of the same age. The objective of this study was to explore this phenomenon in patients with post-polio syndrome and chronic pain with Quantitative Sensory Testing, a method more precise than the normal bedside examination. The study showed that post-polio patients in fact appear to have an overrepresentation of sensory abnormalities, and one may speculate that this might be a contributing factor in the development of chronic pain.