Cancer survivors post-chemotherapy exhibit unique proprioceptive deficits in proximal limbs

Postural control impairments following neurotoxic chemotherapy in women with cancer: a prospective observational study

PURPOSE

This study aimed to compare changes in postural control in different testing conditions involving sensory disturbances, quality of life and neurotoxicity concerns in women with cancer before and after chemotherapy with taxanes. The second aim was to compare postural control between chemotherapy-induced peripheral neuropathy (CIPN) severity subgroups.

METHOD

The 33 participants with breast cancer (age 48.15 ± 9.88 years) were tested during the month preceding (baseline) and the month after the end of chemotherapy. Postural control was assessed on a force platform (100 Hz) in different conditions: eyes open/closed, rigid/foam surface, with/without tendon vibration, dual task, and limits of stability. CIPN severity and neurotoxicity concerns were also evaluated. Paired t-tests or Wilcoxon sign rank tests were used, and a Benjamini-Hochberg correction was applied.

RESULTS

After chemotherapy, greater postural adjustments were required to maintain balance in the reference condition (p ≤ 0.02), and in conditions with visual (p ≤ 0.02), foam (p ≤ 0.04), and dual task disturbances (p ≤ 0.01), but not in the vibration and limits of stability conditions. No difference was found between the CIPN subgroups. The neurotoxicity score worsened after chemotherapy (-8.61 ± 7.53, p ≤ 0.01).

CONCLUSIONS

Postural control was impaired after chemotherapy, particularly in conditions with visual disturbances and dual task. Anteroposterior center of pressure displacements with mediolateral ground reaction forces were particularly increased.

CLINICAL IMPLICATIONS

Systematic assessment of postural control with eyes closed in women with breast cancer would help to identify chemotherapy-induced postural control disorders and determine treatment needs.

TRIAL REGISTRATION

Clinical Trial Registration number NCT04692168. Registration date: 28.12.2020.

Motor disorders related to oxaliplatin-induced peripheral neuropathy: long-term severity and impact on quality of life

PURPOSE

Sensory chemotherapy-induced peripheral neuropathy (CIPN) is well-recognized, but motor CIPN remains understudied. This secondary analysis focused on the long-term severity and impact of motor disorders, their relation to sensory CIPN, neuropathic pain, psychological distress, and health-related quality of life (HRQoL) after oxaliplatin-based chemotherapy in colorectal cancer (CRC) survivors.

METHODS

Data from a multicenter, cross-sectional study were re-analyzed to explore motor CIPN among CRC survivors up to 5 years post-chemotherapy, with no longitudinal follow-up. Questionnaires assessed sensory and motor CIPN (QLQ-CIPN20), neuropathic pain (DN4), anxiety and depression (HADS), and HRQoL (QLQ-C30).

RESULTS

Among 405 CRC survivors, 31.1% had sensory CIPN as previously described. When categorizing the 405 CRC survivors based on the years since their last oxaliplatin-based chemotherapy, the motor scores derived from the QLQ-CIPN20 showed no significant difference between years (p = 0.08). Motor CIPN scores correlated with female gender, higher oxaliplatin dose intensity, sensory CIPN, and neuropathic pain. Motor CIPN also linked to decreased HRQoL and increased psychological distress.

CONCLUSION

The study underscores the detrimental impact of motor disorders on CRC survivors post-oxaliplatin-based chemotherapy. Oncologists should prioritize assessing and managing motor manifestations alongside sensory symptoms to enhance post-cancer quality of life.

TRIAL REGISTRATION

NCT02970526 (2016-11-22). https://classic.

CLINICALTRIALS

gov/ct2/show/NCT02970526?term=NCT02970526&draw=2&rank=1 .

Cancer survivors post-chemotherapy exhibit unimpaired short-latency stretch reflexes in the proximal upper extremity

Oxaliplatin (OX) chemotherapy can lead to long-term sensorimotor impairments in cancer survivors. The impairments are often thought to be caused by OX-induced progressive degeneration of sensory afferents known as length-dependent dying-back sensory neuropathy. However, recent preclinical work has identified functional defects in the encoding of muscle proprioceptors and in motoneuron firing. These functional defects in the proprioceptive sensorimotor circuitry could readily impair muscle stretch reflexes, a fundamental building block of motor coordination. Given that muscle proprioceptors are distributed throughout skeletal muscle, defects in stretch reflexes could be widespread, including in the proximal region where dying-back sensory neuropathy is less prominent. All previous investigations on chemotherapy-related reflex changes focused on distal joints, leading to results that could be influenced by dying-back sensory neuropathy rather than more specific changes to sensorimotor circuitry. Our study extends this earlier work by quantifying stretch reflexes in the shoulder muscles in 16 cancer survivors and 16 healthy controls. Conduction studies of the sensory nerves in hand were completed to detect distal sensory neuropathy. We found no significant differences in the short-latency stretch reflexes (amplitude and latency) of the shoulder muscles between cancer survivors and healthy controls, contrasting with the expected differences based on the preclinical work. Our results may be linked to differences between the human and preclinical testing paradigms including, among many possibilities, differences in the tested limb or species. Determining the source of these differences will be important for developing a complete picture of how OX chemotherapy contributes to long-term sensorimotor impairments.NEW & NOTEWORTHY Our results showed that cancer survivors after oxaliplatin (OX) treatment exhibited stretch reflexes that were comparable with age-matched healthy individuals in the proximal upper limb. The lack of OX effect might be linked to differences between the clinical and preclinical testing paradigms. These findings refine our expectations derived from the preclinical study and guide future assessments of OX effects that may have been insensitive to our measurement techniques.

Mechanosensory encoding dysfunction emerges from cancer-chemotherapy interaction

Persistent sensory, motor and cognitive disabilities comprise chemotherapy-induced neural disorders (CIND) that limit quality of life with little therapeutic relief for cancer survivors. Our recent preclinical study provides new insight into a condition impacting the severity of chronic CIND. We find that sensorimotor disability observed following cancer treatment exceeds that attributable to chemotherapy alone. A possible explanation for intensified disability emerged from evidence that codependent effects of cancer and chemotherapy amplify defective firing in primary sensory neurons supplying one type of low threshold mechanosensory receptor (LTMR). Here we test whether cancer's modification of chemotherapy-induced sensory defects generalizes across eight LTMR submodalities that collectively generate the signals of origin for proprioceptive and tactile perception and guidance of body movement. Preclinical study enabled controlled comparison of the independent contributions of chemotherapy and cancer to their clinically relevant combined effects. We compared data sampled from rats that were otherwise healthy or bearing colon cancer and treated, or not, with human-scaled, standard-of-care chemotherapy with oxaliplatin. Action potential firing patterns encoding naturalistic mechanical perturbations of skeletal muscle and skin were measured electrophysiologically in vivo from multiple types of LTMR neurons. All expressed aberrant encoding of dynamic and/or static features of mechanical stimuli in healthy rats treated with chemotherapy, and surprisingly also by some LTMRs in cancer-bearing rats that were not treated. By comparison, chemotherapy and cancer in combination worsened encoding aberrations, especially in slowly adapting LTMRs supplying both muscle and glabrous skin. Probabilistic modeling best predicted observed encoding defects when incorporating interaction effects of cancer and chemotherapy. We conclude that for multiple mechanosensory submodalities, the severity of encoding defects is modulated by a codependence of chemotherapy side effects and cancer's systemic processes. We propose that the severity of CIND might be reduced by therapeutically targeting the mechanisms, yet to be determined, by which cancer magnifies chemotherapy's neural side effects as an alternative to reducing chemotherapy and its life-saving benefits.