Covid-19 lessens cancer pain in case study

The absence of dyspnoea, despite lower than normal oxygen levels, in some Covid-19 patients may be due to the same root cause as the decreased perception of pain in some cancer patients with Covid-19. — Kwong Wah Jit Poh

Physicians from the Geneva University Hospitals (HUG) have observed a surprising phenomenon during the second wave of the Covid-19 pandemic in Switzerland.

Some patients with cancer-related pain have experienced a significant decrease in, or even disappearance of, pain perception during the acute phase of the infection.

This was revealed in an article, published in the scientific journal Pain, by a multidisciplinary team from HUG, led by Division of Palliative Medicine senior resident Dr Lisa Hentsch and Division of Internal Medicine senior resident Dr Matteo Coen.

Until now, several factors related to Covid-19 have been widely accepted as worsening chronic pain.

However, the team found that three cancer patients suffering from severe Covid-19 had a significant, albeit transient, reduction of their pain.

The patients, three men aged 67 to 84 years old, were outpatients of the palliative care division and had severe cancer pain that did not respond to opioid treatment.

Hospitalised at the HUG due to Covid-19, all three patients observed a decrease, and even a disappearance, of their pain soon after infection.

The recovery from Covid-19 was also associated with a gradual return of pain in one of the patients.

At the moment, this phenomenon remains unexplained, but the team is making a few assumptions.

In a previous article published in the Journal of Medical Virology, the authors discussed another very common phenomenon in patients suffering from severe Covid-19: the absence of dyspnoea (difficulty in breathing) despite lower than normal oxygen levels.

This condition is commonly known as “happy hypoxia”.

Both pain and dyspnoea are subjective experiences that result from complex mechanisms in which the insular cortex plays an essential role.

The insular cortex, or insula, is a part of the cerebral cortex, buried deep in the folds of the brain cortex.

It plays a role in different body functions.

In particular, the insula is responsible for the “awareness” of internal perceptions (interoception) – an essential element for the construction of experiences such as pain and dyspnoea.

A dysfunction of this area, due to a direct effect of the SARS-CoV-2 virus, or as a consequence of the “inflammatory storm” common in severe Covid-19, could indeed be responsible for a blunted, or even absent, perception of pain and dyspnoea.

An alternative hypothesis could be a direct, SARS-CoV-2-induced dysfunction in the peripheral nervous system.

This could result in interference with the transmission of nerve messages responsible for pain and laboured breathing perceptions.

Further studies are needed to confirm these observations and validate these hypotheses.

Nevertheless, these observations could shed new light on the mechanisms responsible for the perception of pain, and eventually open up new avenues of research and therapy.