As the name Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) suggests, the virus that causes Covid-19 is often focused on as a condition that causes breathing difficulties through infection and inflammation of the respiratory system.
However, there have been reports of various neurological manifestations – one which is common and most which are uncommon.
Anosmia refers to the lack of smell, whereas hyposmia refers to a decreased sense of smell. Thought to be a common early symptom of a developing case of Covid-19, it is not well understood why this neurological phenomenon occurs. In the setting of this pandemic, a sudden onset of a loss of smell may be reason to pursue Covid-19 testing. This neurological symptom is not life-threatening, but is quite common.
Less commonly, ischemic stroke can be seen in people with Covid-19 who have a significant increase inflammation, which causes a hypercoagulable (more likely to form blood clots) state. In other cases, the virus may cause an injury to the heart, which increases risk for a clot to form in the heart that can travel to the brain. Stroke has been described in otherwise healthy people who have Covid-19 but no traditional stroke risk factors. People who have Covid-19 are candidates for typical stroke treatments such as thrombolytics or endovascular therapies to remove clots. If a person is hospitalized with Covid-19, the treating provider may start a preventative blood thinner to lower risk of stroke or other clotting diseases.
Encephalitis is a term for inflammation of the brain. Covid-19 has been noted to cause a rare form called Acute Necrotizing Hemorrhagic Encephalopathy. Thought to be more likely due to a massive inflammatory response to the virus that causes breakdown of the blood-brain barrier and inflammation in the brain rather than direct viral infection of the brain, this can result in significant disease of a deeper structure of the brain called the thalamus as well as the brainstem. This is diagnosed with lumbar puncture for analysis of the cerebrospinal fluid as well as MRI of the brain.
Seizure is unlikely to be caused by Covid-19 itself. However, in a person who has an underlying seizure disorder, the fever or inflammation can lower the seizure threshold and make the person more likely to have breakthrough seizures. Aggressive use of medications to treat fever and consideration for a temporary increase in seizure medication doses may help combat this.
Guillain-Barre syndrome (GBS) is an immune mediated condition that causes demyelinating damage to the peripheral nervous system that can occur in a delayed fashion following various infectious or traumatic events. This has been described rarely occur about one to two weeks following a Covid-19 illness. This can result in numbness or tingling in the arms and legs followed by weakness and loss of reflexes. It is important that GBS be diagnosed early by a Neurologist, as it can be treated with immune therapies and it is important to watch for complications.
Fortunately, most Covid-19 illnesses do not cause life-threatening neurological disease. Still, a variety of neurological conditions have been associated with this pandemic; It is important that a Neurologist is available to evaluate for and treat these conditions.