Are you also one of those people hypnotized by space travel?
Can’t get on board a space ship soon enough? In this inter-galactic blog post we will find out whether space travel has any effects of sensory and pain processing.
Walking on the Moon
Space travel must be an enormously broadening and rewarding experience, however, the effects of microgravity on the human body can pose some short and long-term challenges.
Returning astronauts often complain of neck and back pain in space and after their landing, sometimes even lasting for months or years after their visit to space.
The exact mechanisms affecting pain in space travelers have not been entirely elucidated, but several have been proposed, among them: sarcopenia (muscle wasting), inflammatory processes and radiation.
To the moon and back
In its first in its category pilot study (no pun intended) involving a multinational team of researchers (Sauer, 2023), two astronauts underwent quantitative sensory testing (QST) with Medoc’s Q-Sense for thermal thresholds using the method of Limits, mechanical detection thresholds with Von Frey, Temporal Summation (TS) with the Pinprick, and Conditioned Pain Modulation (CPM) with a thermal “test stimulus” (Q-Sense), and a cold bath as a “conditioning stimulus”. Testing sites for QST were at the forearm and the lower back.
The astronauts also filled pain related questionnaires: the State-Trait Anxiety Questionnaire (STAI), the Medical Outcomes Short Form 12 Health Survey (SF-12), the Quebec Back Pain Disability Scale (QBPDS), the Short Form McGill Pain Questionnaire (SF-MGP) and underwent qualitative interviews.
QST was performed pre- and post-flight, both within two weeks of the flight, and after three months post-flight. Questionnaires were filled at these times and also during the flight.
A sky full of stars
During and right after flight, both space travelers suffered from musculoskeletal back pain, which returned to normalcy after three months. This is in line with the known phenomenon “Space Adaptation Pain” that describes usually back pain that appears within the first 24-48 hours of space flight under microgravity and lasts between 9-15 days.
In terms of QST results pre- and post-flight, several changes were found. Temporal summation was increased post-flight at the forearm site, but not at the back. Heat pain increased post flight, apparent from the temperature heat pain threshold and the temperature for moderate heat pain which decreased. After the flight, CPM effect decreased. It isn’t clear whether the back pain episode in space affected the CPM, or whether the decrease in CPM caused a heightened sensitivity to pain.
This small pilot study shows short-term changes to pain sensitivity following space travel, as tested using QST. The inter-relations between exposure to micro-gravity and sensory functioning and pain processing, have not yet been elucidated and further testing possibly in space, should be considered.
References
Sauer, A. K. (2023). Pain Experience and Sensory Changes in Astronauts During and After Short-Lasting Commercial Spaceflight: A Proof-of-Concept Study. Journal of Pain Research, 4253-4266.