The main manifestations of infection with the new COVID-19 coronavirus include dry cough, fever, malaise and, in severe cases, respiratory distress. The agent responsible is the SARS-Cov-2 virus, a beta-coronavirus very similar to the severe acute respiratory syndrome (SARS) virus.
In general, direct involvement of the nervous system by SARS-Cov-22 is considered to be limited. However, a high percentage of indirect neurological problems, related to the inflammatory response and prothrombotic state associated with the infection, failure of other organ systems (e.g. respiratory failure, renal failure) and prolonged immobility, can be expected.
Along these lines, in a series of 214 patients admitted in Wuhan (China), about one third of the subjects (36.4%) had neurological symptoms, including cerebrovascular disease, decreased level of consciousness, and muscle lesions (Mao et al, 2020). The case of a patient with diffuse encephalopathy without signs of infection in the cerebrospinal fluid also supports indirect involvement of the nervous system by SARS-Cov-2 (Filatov et al, 2020).
In contrast, previous studies in humans and experimental animals have shown that the SARS coronavirus is capable of infecting the nervous system, especially at the brainstem level (Ly et al, 2020). This data suggests that respiratory distress may have a central component, apart from the respiratory component. The mediator of access to the nervous system and other cells could be the angiotensin-converting enzyme 2 receptor (Baig et al, 2020). From the clinical point of view, isolated cases of acute encephalitis of benign course associated with COVID-19 have been described (Encephalitis Society, 2020).
Among the neurological symptoms associated with COVID-19 is acute confusional syndrome or diffuse encephalopathy.
This condition is very frequent in critically ill patients and especially in the elderly with previous cognitive impairment. It is characterized by an acute deterioration of mental status, including a variable combination of inattention, temporal and spatial disorientation, disturbance of sleep-wake rhythms, visual hallucinations, delusions and psychomotor agitation.
Another common neurological condition in critically ill patients is neuromyopathy of the critically ill.
It consists of a generalized loss of strength resulting from muscle or peripheral nerve involvement. Although this problem is generally reversible, it makes it difficult to withdraw mechanical ventilation and requires a prolonged rehabilitation process.
It has also been reported that 30% of patients infected with COVID-19 consult for loss of smell (anosmia) or loss of taste (ageusia). Although there are neurological diseases that can produce these symptoms, the most likely origin is a mucosal involvement of the nasal mucosa, as in other respiratory infections.
