By Gabriella Kelly-Davies, PNN Columnist

Around the world many people who have recovered from even mild episodes of COVID-19 are presenting to doctors with unrelenting headaches, persistent and intense muscle and joint pain, and other forms of chronic pain that mimic conditions such as fibromyalgia.

Professor Gregory Dore, from the University of New South Wales’ Kirby Institute, is studying the health of people recovering from COVID-19. Known as ADAPT, the study started enrolling patients last year at St. Vincent’s Hospital in Sydney during the first wave of the pandemic in Australia. Most of the patients reported mild or moderate COVID symptoms.

One aspect of the ADAPT study is looking at neurological markers that reflect inflammation in the nervous system. The results aren’t public yet, but Dore says the findings are consistent with neuro-inflammation, which can appear in conditions such as persistent headache and nerve pain.

“We are seeing many patients with headaches so severe they require an MRI,” Dore said. “Headache can be part of the acute illness, but it is also persisting in many patients months after they recovered from the initial infection. It’s much more prevalent than in the general population.”

Dore is surprised by the number of “long haul” COVID patients who are presenting with ongoing neurological conditions four and eight months after they recovered from the initial infection.

“This was a pretty healthy group,” he said. “Most of the people we saw in the first wave of COVID were coming back from overseas. They were doing things like skiing and traveling and were a healthy bunch. I initially thought most people would have recovered by six months, but it seems to be ongoing. Immunology tells us there could be an ongoing immune response that is causing the neurological conditions, including pain.”

Neurological Infections

Dr. Daniel Carr, a prominent American pain specialist at Tufts University School of Medicine, says there are three primary mechanisms underpinning chronic pain after an acute COVID infection.

One is a direct attack by the virus on a variety of tissues such as nerves, the spinal cord and brain. Another is overactive inflammatory cascades attacking the body’s tissues and organs. This means one area of inflammation can ignite another in a continuous chain reaction and spread throughout the body. The third way is excessive blood clotting provoked by the virus, which may lead to gangrene, limb amputation and phantom limb pain.

Professor Bart Morlion, former president of the European Pain Federation and Director of the Leuven Center for Pain Management in Belgium, agrees. In the rehabilitation centre at his hospital, he is seeing patients with three forms of chronic pain following an acute COVID infection. Nerve pain is common because if the virus attacks the spinal cord, it can leave the patient with scarring of the spinal cord and intractable pain.

“I’ve seen patients who developed paraplegia because of an acute inflammation of the spinal cord induced by COVID-19, which is comparable to what we see in paraplegic patients after spinal cord injury,” Morlion explained. “There are also cases of encephalitis, meaning the virus infected brain tissue.”

The same is true when the COVID infection triggers a stroke. Patients can develop chronic nerve pain or widespread pain throughout the body, which is difficult to manage.

Morlion has seen several patients who have secondary pain problems after a COVID infection. Some patients developed thromboembolism – a closure of their arteries and small blood vessels – and developed gangrene in their limbs. To save their lives, surgeons had to amputate their arms or legs.

“We have patients in rehabilitation who lost both legs and arms because of COVID,” Morlion said, “and they have developed phantom limb pain.”

COVID patients who stayed in intensive care on a ventilator for an extended period are also ending up with chronic pain conditions. Morlion has treated many patients who’ve developed a painful infection of the small fibres in the nervous system. Patients who lay flat their stomachs while in intensive care to enhance their breathing are also developing chronically painful shoulders and elbows because of damage to the joints and nerves.

“If an intensive care nurse had to take care of five patients who required turning every few hours, then it happens that for instance, the elbow isn’t protected enough, leading to ‘park bench syndrome’ where the patient gets a chronically numb and painful little finger, because of the prolonged pressure on their elbow,” Morlion said. “Turning itself is always a risk for nerve and joint damage because these patients are floppy and can’t move into a comfortable position.”

COVID is also intensifying pre-existing pain conditions. One-fifth of the world’s population live with chronic pain, and Morlion is seeing many of these patients in his pain centre because their previously well managed chronic pain has increased by orders of magnitude after recovering from an acute COVID infection.

Dr. Marc Russo, an Australian pain physician, believes that special research units need to be set up to enable doctors to collect data on chronic pain conditions so dedicated treatments can be designed.

“We need one in Sydney and another in Melbourne that are multidisciplinary and include a pain physician, immunologist, infectious disease physician, rehabilitation physician and nursing case manager,” he said.

Chronic pain was already one of the major causes of disability before COVID-19, but it looks like the pandemic has swelled the number of people living with intractable pain. Our health systems must invest in the multidisciplinary pain management services needed to ease the  suffering caused by the multiple pain conditions resulting from COVID infection.

Gabriella Kelly-Davies is a PhD student at Sydney University who lives with chronic migraine.

Gabriella is the author of “Breaking Through the Pain Barrier,” a biography of her physician, Dr. Michael Cousins, who co-founded Painaustralia and is a world renowned expert in pain management.