From the WebMD Archives

March 23, 2021 -- Cognitive dysfunction, sometimes called “brain fog,”tops the list of neurologic complaints in patients with long-haul COVID-19 whose illness wasn't severe enough for them to be hospitalized, new research shows.

But brain fog isn’t the only problem, the study found.

Researchers, who tracked 100 non-hospitalized patients with long-haul COVID-19 from May to November found 85% reported four or more neurologic symptoms.

"It's the first of its kind study on neurological symptoms appearing in patients non-hospitalized," senior author Igor Koralnik, MD, professor of neurology at Northwestern University in Chicago told Medscape.

"Most of what we know today [about long-haul COVID-19 patients] is what is happening in patients severely sick in the hospital," Koralnik, who is also chief of neuro-infectious disease and global neurology, said.

The study was published online today in Annals of Clinical and Translational Neurology.

Persistent, Debilitating Symptoms

The tracked patients had symptoms consistent with COVID-19, said Koralnik, but only mild and fleeting respiratory problems. None developed pneumonia or low oxygen levels that would have required hospitalization.

Seventy percent of the patients in the study were women, and the average age was 43.

Long-haul COVID-19 was defined as symptoms persisting for more than 6 weeks, with the consensus that most patients fully recover from COVID-19 in 4 to 6 weeks.

What was surprising, said Koralnik, was that the patients, despite not needing hospitalization, had persistent and debilitating symptoms for months after symptoms began.

The investigators also found recovery varied from patient to patient, making it was difficult to predict whether a specific symptom would likely ease within a certain timeframe.

The 10 most common complaints among study participants were:

  • Cognitive dysfunction, reported by 81%
  • Headache, 68%
  • Numbness or tingling, 60%
  • Loss of taste, 59%
  • Loss of smell, 55%
  • Muscle pain, 55%
  • Dizziness, 47%
  • Pain, 43%
  • Blurred vision, 30%
  • Tinnitus (ringing in the ears), 29%

In addition, many reported non-neurologic symptoms, including:

The researchers tracked 50 long-haul COVID-19 patients who had laboratory-positive tests and 50 with lab-negative tests, although all met the definition of COVID-19 by criteria set by the Infectious Diseases Society of America, Koralnik said.

This reflects the limitations of early testing, he added. Early in the pandemic, people often could not get a test, could not get a test in the timeframe that would accurately detect infection, or had a test that wasn't sensitive enough to detect infection accurately, he said.

Study participants resided in 21 states. Fifty-two were seen in-person and 48 by telehealth at a neuro COVID-19 clinic. They had either limited or comprehensive cognitive testing; memory and attention deficit problems were common.

Many patients (42%) reported depression or anxiety prior to COVID diagnosis, said Koralnik, suggesting a "neuropsychiatric vulnerability" to developing long-haul COVID-19.

Although the study did not aim to explain why some patients develop long-haul COVID-19, it suggests autoimmune mechanisms may be at play, the investigators note.

The range of symptoms varied widely, with some patients experiencing cognitive impairment and dizziness, with no smell or taste issues, or vice versa, said Koralnik.

Predicting recovery from specific symptoms is not yet possible, he noted.

"People tend to improve over time, but they do it at their own pace," he said.

"We were hoping the further away from the disease onset, the better the patient would feel recovered. In fact that was not the case," said Koralnik.

Some said, for instance, they were 95% recovered after 2 months, while others said they were only 10% recovered after 9 months. That means it is impossible to tell a patient with specific symptoms to expect recovery after a specific period of time, he noted.

Accurate Reflection of Clinical Practice

Commenting on the findings, Allison Navis, MD, assistant professor of neuro-infectious diseases at the Icahn School of Medicine at Mount Sinai in New York City and lead clinical neurologist at the Post-COVID Center at Mount Sinai, said they reflect clinical practice and noted that she has seen at least 200 long-haul patients.

She welcomed the study's focus on neurologic symptoms and noted ''we don't fully understand what is going on" with the long-haul patients.

"We are seeing improvement for a lot of people, but it is taking some time. For some of the more debilitating symptoms, we have treatments," such as effective headache medications.

One promising clue from the study, said Navis, who was not involved in the research, is the idea that the long-haul symptoms might be an autoimmune response, maybe similar to some other post-infection syndromes.

The study shows that that it's important not to be dismissive of patients' persistent symptoms. " 'Just get over it' is not the correct approach," she said.