Somatosensory Profile of Central Post Stroke Pain of Thalamic Origin: Findings of a Quantitative Sensory Testing Study

Introduction

Central post stroke pain (CPSP) is attributed to vascular lesions of the central somatosensory system, including the thalamus.

Objective

A better characterisation of clinical findings in patients with CPSP after thalamic stroke can facilitate research and treatment of this refractory pain syndrome. We aimed to quantify somatosensory abnormalities in CPSP patients after thalamic stroke.

Methods

Sixteen patients with CPSP after thalamic stroke, 14 patients with a history of thalamic stroke without any pain (stroke control patients, SCP) and 12 healthy controls (HC) underwent detailed clinical examination, standardised quantitative sensory testing (QST) and a pain questionnaire. QST results were compared to age and sex adjusted reference data to obtain z-scores. Group comparisons were performed with one-way analysis of variance.

Results

Temperature perception did not differ in CPSP patients, apart from thermal sensory limen (higher in CPSP vs. HC but no difference vs. SCP). Patients with CPSP showed higher mechanical detection thresholds compared to SCP (Δ = 1.26, p = 0.017, no difference vs. HC) and they were more sensitive to mechanical pain than SCP (lower mechanical pain thresholds vs. SCP: Δ = −1.32, p = 0.014, no difference vs. HC).

Conclusion

Our results indicate somatosensory abnormalities in patients with CPSP after thalamic stroke, associated with the perception of mechanical stimuli. A short somatosensory screening including mechanical perception may contribute to an accurate diagnosis of this debilitating condition.

Significance Statement

Thalamic CPSP is very rare, thus our data contribute to the clinical and sensory phenotyping of patients suffering from this debilitating condition. We did not find abnormalities in thermal measures, but only mechanical thresholds in our cohort, suggesting that not only changes in temperature perception are necessary for the development of pain after thalamic stroke. Our findings suggest that a short QST protocol including mechanical testing using von Frey filaments and pin-prick-stimulators may be useful in the diagnosis of thalamic CPSP.