Can Neuron Specific Enolase Be a Diagnostic Biomarker for Neuronal Injury in COVID-19?

Neuron specific enolase (NSE) is a biomarker for neuronal injury. However, increased levels in cerebrospinal fluid (CSF) and serum is associated with the clinical outcome in patients with head injury, ischemic stroke, intracerebral hemorrhage, cardiac arrest, anoxic encephalopathy, encephalitis, brain metastasis, and status epilepticus. Recently, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, which started in China, rapidly evolved into the coronavirus disease 2019 (COVID-19) pandemic. Patients with COVID-19 have a wide range of symptoms varying from mild upper respiratory symptoms to severe illness requiring mechanical ventilation. While coronaviruses primarily target the human respiratory system, neurological symptoms are also observed in some patients. These include symptoms such as loss of taste and olfaction and diseases like cerebrovascular disorders including ischemic stroke and hemorrhages, encephalopathies, Guillain-Barré syndrome and acute disseminated encephalomyelitis. Here we report an observation from a patient whose NSE levels increased approximately four-fold in CSF. This finding was accompanied by increased white blood cell count and elevated protein in CSF indicating neuroinflammation. Thus, we suggest that NSE may be used as a CSF biomarker in COVID-19 patients with encephalopathy.