**4.1 Headache and dizziness: central neurological findings**

Headache is one of the most commonly reported neurological symptoms of a systemic viral infection. Although direct mechanisms of this symptom are yet to be discovered, there are some possible causes. High body temperature directly causes activation of several immunoinflammatory mediators (cytokines, glutamate, cyclooxygenase-2/prostaglandin E2 system, and nitric oxide system) and activation of substances that are capable of inducing interleukins (exogenous and endogenous pyrogens). Some of the indirect causes are dehydration, electrolyte disbalance, hypoxia, systemic inflammation, and cytokine release syndrome (CRS). One of the possibilities for developing this symptom could also be direct infection of the nervous system via ACE-2 receptors [43].

Vertigo or dizziness has been described as the most common neurological manifestation of COVID-19. Neurotropism of SARS-CoV-2 causes the virus to invade neural tissue from circulation through capillary endothelium (ACE-2 receptors). Aside from this mechanism, direct invasion, hypoxia, and systemic inflammation play the part in causing this symptom. Approximately 7.0% (2.5% to 21.4%) of the COVID-19 patients were reported to have this symptom.

Combined manifestation of dizziness and headache occurred in 12.1% as has been reported in eight studies, with a total of n=654 patients [44].

#### **4.2 Impaired consciousness: central neurological findings**

As anticipated, severe or critical patients tend to develop impaired consciousness (11.9%) due to hypoxia and cerebrum impairment. In patients with mild or asymptomatic clinical manifestations, the prevalence of this symptom is considerably lower (3.2%). The number of studies taken into account was nine, including n=2890 patients with impaired consciousness [45].

#### **4.3 Acute cerebrovascular complications: central neurological findings**

The most common display of cerebrovascular disease is an acute stroke with rapidly evolving symptoms which may include weakness of one side of the face or body, numbness, motor or sensory aphasia, ataxia, visual impairment. Those symptoms could be manifested due to compromised blood supply to the brain and which symptom will develop depends on the compromised area of the cerebrum. Regarding this clinical problem, two cohort studies were conducted. The first study by Mao et al. noted that among 214 hospitalized patients, 6 patients developed acute cerebrovascular manifestation (2.8%) [46]. The second study by Li et al. reported 11 patients with acute ischemic stroke (including a total of 221 COVID-19 patients). It has been shown that developing acute cerebrovascular events is highly correlated with the age of the patients (71.6 ± 15.7 years/52.1 ± 15.3 years) [47].

#### **4.4 Seizures: central neurological findings**

An epileptic seizure is a "transient occurrence of signs and/or symptoms due to abnormal excessive or synchronous neuronal activity in the brain" [48]. There are few reports of acute seizures in SARS-CoV-2 positive patients. The first study regarding this clinical manifestation was noted in a COVID-19 patient, a 24-yearold male with generalized seizures, from Japan [49]. The second publication reported a COVID-19 patient, a 30-year-old female with generalized tonic–clonic seizures, from Iran. In both cases, there was no evidence of previous seizures, prior to hospitalization [50]. Even though these and similar reports may suggest that correlation between seizures and COVID-19 infection exist, there are a relatively low number of reported cases so far, therefore a seizure risk is caused by nonspecific mechanisms (hypoxia, cerebrovascular events, cytokine proliferation, etc.).

#### **4.5 Meningitis/encephalitis: central neurological findings**

By definition, meningitis is inflammation of the meninges, in almost all cases identified by an abnormal number of leukocytes in the cerebrospinal fluid and specific symptoms. The etiology may be noninfectious and associated with a systemic disease, medication, or other pathologic factors. However, most cases of

#### *Neurological Involvement in COVID-19 DOI: http://dx.doi.org/10.5772/intechopen.99309*

aseptic meningitis are caused by viruses. There have been interpreted few singlecase reports, regarding meningitis/encephalitis in correlation with COVID-19. Anyhow, only a few of reported cases tested positive for SARS-CoV-2. The first described case was reported from China, but the amount of clinical evidence was underwhelming [51]. Another case was reported in a SARS-CoV-2 positive patient from Japan, manifested as generalized seizure and pathological cerebral MRI (right lateral ventriculitis and encephalitis mainly on the right mesial temporal lobe and hippocampus) [52]. In other reported cases, patients tested negative for SARS-CoV-2, or even were not tested at all [53].
