A COVID-19 patient in Texas who had no respiratory symptoms for the virus has suffered brain damage, which is causing concern for some scientists.
The 30-year-old male had difficulty speaking and walking - signs of damage to the cerebellum, which controls balance and coordination - but didn't have any common symptoms of COVID-19, including a fever, cough or chest pains.
"COVID-19 has not yet been reported as a cause of acute viral cerebellitis without associated respiratory symptoms," Adriana Povlow and Andrew Auerbach from the University of Texas Health Science Centre wrote in a study published in the Journal of Emergency Medicine on Friday.
"Previous reports of neurological deficits were from those that were symptomatic and included confusion, dizziness, impaired consciousness, propensity to develop acute strokes, anosmia, hypogeusia, ataxia, epilepsy, and neuralgia."
The patient arrived at hospital with nausea, vomiting, slurred speech and difficulty walking, leading doctors to believe he had suffered a stroke. Brain scans found no bleeding in his head, but instead X-rays showed mild inflammation in the upper lungs.
A COVID-19 PCR test later came back positive.
He spent 10 days in hospital and had some improvement in his neurological symptoms but still needed a walking frame for ataxia, a lack of muscle control or coordination, once he was discharged.
The authors urged medical staff to "keep a high level of suspicion" for COVID-19 infections in patients that show neurological symptoms at the onset.
Another study published in the Annals of Clinical and Translational Neurology says more than 80 percent of people hospitalised with COVID-19 have neurological symptoms such as head and muscle aches, confusion and dizziness.
Researchers for the study found 42.2 percent of patients had neurological symptoms when they first became sick, 62.7 percent reported these symptoms once they were hospitalised and 82.3 percent had them at some point while they were infected with COVID-19.
In the same study, it found about one-third of patients experience encephalopathy, an altered brain function or structure.
Patients who experienced encephalopathy tended to be male, about 65-years old on average and enter the hospital as soon as their COVID-19 symptoms set in.
