Neuro-AIDS

Extracerebral pus collections

This type of purulent lesion of the nervous system is localized predominantly over the cerebral hemispheres or in the interhemispheric fissure.

Clinical presentation and diagnostics The symptom complex includes the development of central hemiparesis and other focal neurological disorders. To confirm the diagnosis, the following are used:

• Neuroimaging (CT and MRI): allows visualization of the localization and volume of the purulent focus.
• CSF (cerebrospinal fluid) analysis: a characteristic feature is neutrophilic pleocytosis (cell count ranging from 50–1000 per 1 mm³).

Therapeutic tactics The management of such patients is based on two main principles:

1. Conservative phase: massive antibiotic therapy following regimens similar to the treatment of brain abscesses.
2. Surgical phase: in the vast majority of cases, emergency surgical drainage of the formed focus is indicated.

Spinal subdural and epidural abscess

Spinal epidural abscess (purulent epiduritis) is a localized purulent inflammation affecting the epidural tissue of the spinal canal.

Etiopathogenesis The main causative agent of the infection is staphylococcus, with gram-negative microorganisms being significantly less common. Infection enters the epidural space through several routes:

• Hematogenous (most frequent): bacteria are carried by the bloodstream from primary infection foci (skin furuncles, infections of the lungs, pharynx, kidneys, urogenital system, and pelvic organs).
• Contact: spread occurs in the presence of spinal osteomyelitis, psoas muscle abscess, retroperitoneal abscess, and also as a result of suppuration following spinal surgeries.

An important risk factor is prior back trauma (noted in 20–30% of patients), which leads to the formation of a small hematoma—an ideal environment for bacterial proliferation.

Localization and symptoms The purulent focus most frequently forms in areas with the maximum volume of epidural adipose tissue: in the lower lumbar and midthoracic ($Th_{IV}$–$Th_{VIII}$) regions. The clinical picture consists of three syndromes:

• General infectious: manifested by a persistent elevation of body temperature.
• Pain: local or radicular pain occurs at the level of the affected segment with local tension of the muscular corset. When the thoracic region is affected, the pain is girdle-like; in the lumbar region, it radiates to one or both lower extremities.
• Neurological deficit: as the process progresses, long-tract sensory disturbances below the compression level, pelvic dysfunctions, and central paresis of the legs join in.

Diagnostic methods and prognosis The diagnosis is based on the clinical triad (signs of inflammation, pain syndrome, spinal cord dysfunction). Mandatory instrumental confirmation is provided by MRI or CT of the spine. If these cannot be performed, contrast myelography is used. Radiography is useful for detecting concurrent osteomyelitis. It is important to remember that performing a lumbar puncture in this pathology is strictly prohibited. Treatment includes a combination of powerful antibacterial therapy and emergency surgical drainage. With timely initiation of treatment, the prognosis is favorable, whereas a delay in therapy threatens death or profound disability.

Shingles (Herpes zoster)

Shingles is a neurotropic disease developing as a result of the reactivation of a latently persisting Varicella-zoster virus (Varicella-zoster virus). Primary infection with this virus in childhood presents as chickenpox, while reactivation of the pathogen occurs in adults. The incidence directly depends on age and is about 3–5 cases per 1,000 people annually.

Features of the disease course

• Prodrome: may be characterized by mild signs of a general infection—malaise, fatigue, and fever.
• Onset: the pathology manifests with unilateral pain, a burning sensation, or hyperesthesia in the projection of several dermatomes.
• Localization: in more than half of the cases, the thoracic segments are affected. In 20% of cases, the ophthalmic branch of the trigeminal nerve (ramus ophthalmicus nervi trigemini) is involved, and in another 20%, the lumbosacral segments.
• Skin manifestations: the rash appears in the painful area a few days later. The development of rash elements has a strict staging: erythematous spots and papules appear first, which then transform into vesicles. In an atypical course, scattered rashes outside the main segment may be observed.

In an uncomplicated course, symptoms regress within a few weeks, leaving behind areas of dyspigmentation or scars.

Complications and treatment of herpes zoster

The most formidable and frequent complication (up to 30% of cases, predominantly in elderly patients) is postherpetic neuralgia. It is characterized by the persistence of pronounced pain syndrome even after the skin rashes have completely cleared. The pain can be of two types:

1. Constant: agonizing, boring, and burning pain in the area of the former rash.
2. Paroxysmal: sudden, cutting, or sharp stabbing.

Diagnostics and therapeutic tactics The diagnosis of shingles is not difficult and is based exclusively on the characteristic clinical picture: a combination of specific pain syndrome with a vesicular rash spreading along the dermatomes. Treatment of uncomplicated forms with moderate pain and sparse rash is symptomatic. Analgesics are used to relieve pain, local antiseptics (to prevent secondary bacterial suppuration), and local anesthetics.

Briefly: answers to topical questions

Class and exam questions

What else to study on this topic

• Clinical classification of extracerebral abscesses
• Antibiotic therapy regimens for purulent neuroinfections
• Pathophysiological mechanisms of postherpetic neuralgia
• Management tactics for severe and atypical forms of herpes zoster
• Indications for contrast myelography in modern neurosurgery

Other topics in "Chapter 23. Infectious Diseases of the Nervous System"

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.