Post-polio syndrome - somatosensory dysfunction and its relation to pain: a pilot study with quantitative sensory testing

Abstract

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

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

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

Methods: 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.

Results: 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.

Conclusion: 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.

Fig. 1

Pain drawings. ^a Left arm pain radiating from subacute, nociceptive shoulder pain and not related to long-lasting PPS pain (according to the patient). ^b Left arm pain marked in the drawing as it was more prominent at the time of examination, but reported by the patient that the pain is usually similar in both arms.

Fig. 2

z-score sensory profiles of patients’ more affected limbs (study sites) and internal control sites (control). Solid, black lines indicating +1.96 SD and –1.96 SD respectively. UE: upper extremity; LE: lower rxtremity; CDT: Cold Detection Threshold; WDT: Warm Detection Threshold; CPT: Cold Pain Threshold; HPT: Heat Pain Threshold; MDT: Mechanical Detection Threshold; MPT: Mechanical Pain Threshold; VDT: Vibration Detection Threshold; PPT: Pain Perception Threshold.

Fig. 3

Skin temperature at study site and control site respectively. UE: upper extremity; LE: lower extremity.