**6.2. Meningitis, encephalitis, and myelitis**

Meningitis is characterized by fever, headache, nausea, vomiting, and meningeal signs. These symptoms and signs are present in the majority but not in all the patients. In a study encompassing 448 adult patients with TBE from Slovenia, almost all reported headache and had fever, more than 50% suffered from nausea and/or vomiting, and 70% had clearly expressed meningeal signs [33]. Encephalitis may manifest by a variety of neurological symptoms and signs, most often with tremor (especially of the fingers of the upper extremities and tongue), sometimes with nystagmus, speech disorder, ataxia and movement disorders, occasionally with seizures, and very rarely with brain stem symptoms and/or cranial nerve abnormalities. Impaired consciousness, ranging from mild to severe, insomnia, and concentration and cognitive function disturbances are rather frequent. Mental disorders including amnesia, behavioral changes, psychosis, and delirium may also occur. Patients may have sensory impairment. Myelitis is virtually always associated with meningoencephalitis, and as a rule manifests with flaccid paralyses that are occasionally preceded by severe pain in the affected muscle groups. The involvement is usually asymmetrical. Most often extremities are affected, more frequently the upper than the lower limbs, and more often the proximal segments of the extremities than the distal ones. Patients with pareses of respiratory muscles usually require artificial ventilatory support [12, 32, 57].

## **6.3. Other manifestations in the acute phase of illness**

#### *6.3.1. Involvement of cranial nerves*

According to rather limited data, involvement of cranial nerves is rare, mostly asymmetrical, typically associated with severe acute illness, and usually has a favorable outcome [46, 47, 58]. Ocular, facial, and pharyngeal muscles are most often affected, but hearing and vestibular defects are also encountered [42].

In a series of 1218 adult patients diagnosed with TBE at a single center, 11 (0.9%) developed peripheral facial palsy (2 bilateral, 9 unilateral); however, 3 out of 11 patients had associated borrelial infection. The latter finding suggests that in patients who develop peripheral facial palsy in the course of TBE, and who had been exposed to ticks in the region where both TBE and Lyme borreliosis are endemic, coexistent infection with Lyme borreliae have to be taken into account [59].

#### *6.3.2. Autonomic disorders*

Occasionally, autonomic nervous system disorders are present in patients with TBE [60].
