Tick-Borne Encephalitis Endemic Areas
Proper collection of epidemiological history and planning of preventive measures require accounting for TBE-endemic areas. According to regulatory frameworks (Order No. 47 of the FMBA of Russia dated April 4, 2016), these include numerous regions of the Russian Federation.
The list includes federal cities — Saint Petersburg and Sevastopol. Vast oblasts are also recognized as endemic: Amur, Arkhangelsk, Vologda, Ivanovo, Irkutsk, Kaliningrad, Kemerovo, Kirov, Kostroma, Kurgan, Leningrad, Novgorod, Novosibirsk, Nizhny Novgorod, Omsk, Orenburg, Pskov, Samara, Saratov, Sakhalin, Sverdlovsk, Tver, Tomsk, Tyumen, Chelyabinsk, and Yaroslavl. The Jewish Autonomous Oblast and the Khanty-Mansi Autonomous Okrug are highlighted separately. In Moscow Oblast, only the Dmitrovsky and Taldomsky districts are considered endemic.
Among the republics, the list includes Altai, Bashkortostan, Buryatia, Karelia, Komi, Crimea, Mari El, Mordovia, Tatarstan, Tuva, Udmurtia, and Khakassia. Krais with a high risk of infection include Altai, Zabaykalsky, Krasnoyarsk, Perm, Primorsky, and Khabarovsk.
Dispensary Observation of Convalescents
The patient management protocol after discharge from the hospital depends on the clinical form of tick-borne encephalitis. Regular examinations by a neurologist and an infectious disease specialist are mandatory, along with laboratory monitoring (ELISA for IgG and IgM antibodies, PCR diagnostics).
- Febrile form: dispensary follow-up lasts for at least 1 year. Examinations and tests are performed at 1, 3, 6, and 12 months. EEG is prescribed only when clinically indicated, and MRI is not regulated.
- Meningeal form: the observation period is extended to 3 years. During the first six months, doctor visits take place at months 1, 3, and 6, and subsequently every 6 months. EEG is performed every 6 months during the first year.
- Focal forms: require observation for at least 5 years. For the first six months, examinations are conducted monthly, then every 6 months. EEG is performed every 6 months for the first three years, and annually thereafter. MRI of the brain or spinal cord in focal lesions is performed 1–3 months after discharge, and then repeated every 6 months until the picture stabilizes.
Neurological Examination: Assessment of Cranial Nerves
Cranial nerve lesions are common in TBE. Examining them helps localize the pathological process:
- Oculomotor nerve (III pair): involvement causes eyelid drooping (ptosis), divergent strabismus (strabismus divergens), pupillary dilation (mydriasis), and restricted eye movement.
- Trochlear (IV pair) and Abducens (VI pair): their damage results in convergent strabismus (strabismus convergens) and double vision (diplopia).
- Trigeminal (V pair): in case of masticatory muscle paralysis, the lower jaw deviates toward the weak muscle when the mouth is opened.
- Facial (VII pair): peripheral paralysis leads to asymmetry of the entire face on the affected side (inability to close the eye — lagophthalmos, drooping corner of the mouth, Bell's sign). In central paralysis, only the lower part of the facial musculature is affected.
- Glossopharyngeal (IX) and Vagus (X) pairs: their involvement leads to swallowing disorders (dysphagia), nasal voice (nasolalia), with the uvula deviating toward the healthy side.
- Hypoglossal (XII pair): when protruding the tongue, it deviates toward the affected side, and speech becomes slurred (dysarthria).
Pathological Reflexes of the Pyramidal Tracts
Structural or functional damage to the pyramidal tracts in meningoencephalitis is accompanied by the appearance of pathological foot signs. These include:
- Babinski sign: isolated extension of the big toe upon stroking the sole.
- Oppenheim sign: a similar response when sliding a finger down the anterior surface of the tibia.
- Gordon sign: extension of the big toe in response to squeezing the calf muscle.
- Rossolimo sign: flexion or fan-like spreading of the toes following a light tap on the tips of toes II–V from the plantar side.
Briefly: answers to topical questions
How is the level of consciousness assessed using the Glasgow Coma Scale?
The degree of impaired consciousness on the Glasgow Scale is assessed by summing the scores of three criteria (minimum 3, maximum 15 points):
- Eye Opening (E) — from 4 points (spontaneous) to 1 point (none/no response).
- Motor Response (M) — from 6 points (obeys commands) to 1 point (none).
- Verbal Response (V) — from 5 points (oriented/coherent speech) to 1 point (none).
The total score is calculated using the formula: E + M + V.
Class and exam questions
What is the difference in deviation when the X and XII cranial nerve pairs are affected?
In lesions of the vagus nerve (X pair), the palatine uvula deviates toward the healthy side. In lesions of the hypoglossal nerve (XII pair), the protruded tongue deviates toward the affected side.
How often should an MRI be performed in the febrile form of TBE?
In the febrile form, as in the meningeal form, MRI of the brain and spinal cord is not regulated. It is mandatory only for focal forms.
How is Bell's sign tested?
This is a sign of peripheral lower motor neuron lesion of the facial nerve. The patient is asked to close their eyes: on the affected side, the palpebral fissure remains open (lagophthalmos), and the eyeball reflexively shifts upward.
What else to study on this topic
- Criteria for assessing the severity of impaired consciousness using the Glasgow Scale (3 to 15 points).
- Methodology for examining pupillary reflexes: direct and consensual light reactions.
- Assessment of pupillary reaction to convergence and accommodation.
- Differential diagnosis of central and peripheral facial nerve palsy.
- Methodology for examining the function of the accessory nerve (XI pair).
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