Perinatal CNS Lesions

Historical aspect and etiological structure

Historically, Russian pediatric practice used the term "perinatal encephalopathy," introduced by Yu.Ya. Yakunin along with the description of the first clinical variants. Today, thanks to the introduction of modern instrumental neuroimaging methods, understanding of the causes and mechanisms of damage has deepened significantly.

Four isolated groups and one mixed group are distinguished in the structure of causes (presented in descending order of frequency):

1. Hypoxic-ischemic (48%). The absolute leader. Includes pathological conditions caused by oxygen deprivation (ischemia) and intracranial hemorrhage.
2. Infectious (23%). Arises from the impact of specific pathogens (viruses, bacteria, parasites) as part of intrauterine and neonatal infections.
3. Mixed etiology (19%). In clinical practice, isolated causes do not always occur. Most often, infectious, metabolic, or traumatic factors are superimposed on baseline hypoxia.
4. Traumatic (5%). Caused by mechanical damage to the brain, spinal cord, or peripheral nervous system directly during delivery.
5. Toxic-metabolic (5%). Associated with severe disruptions of carbohydrate or calcium-magnesium metabolism, deficiency states (e.g., vitamin K deficiency provoking hemorrhages), and direct toxic effects on the fetus.

Pathogenetic cascade and cellular mechanisms

The development of perinatal CNS damage represents a strictly sequential chain of metabolic and vascular catastrophes:

• Trigger factor: exogenous impact on the nervous system.
• Vascular stage: development of ischemia and pathological redistribution of cerebral blood flow.
• Biochemical stage: massive glutamate release (excitotoxicity), disruption of intracellular calcium homeostasis, and accumulation of lactic acid (tissue lactic acidosis).
• Organ-hemodynamic stage: brain edema and swelling leading to a breakdown of cerebral autoregulation.
• Morphological outcome: formation of ischemic foci.

Against the background of this catastrophe, a struggle between damage and compensation unfolds in the nervous tissue. Primary massive neuronal loss occurs via necrosis. In unfavorable courses, apoptosis (involving thanatin proteins) is triggered—programmed cell death that expands the zone of damage into healthy cortico-subcortical structures. However, if timely therapy halts apoptosis, the mechanism of neuroplasticity is activated—sprouting. Surviving neurons form new processes, allowing a small group of cells (dozens) to take over the functions of thousands of dead ones.

Role of infections in the development of pathology

Infectious agents play a dominant role in the structure of severe lesions. Primarily, these are classical TORCH pathogens (toxoplasmosis, rubella, cytomegalovirus, herpes).

It has been proven that herpes simplex virus (HSV) can act as a direct trigger activating apoptosis in brain tissue. Furthermore, enteroviruses are gaining increasing importance in pathogenesis, with their impact showing a high degree of correlation with the development of severe and irreversible CNS damage.

Functional consequences and outcomes

Prognosis and clinical presentation directly depend on the final volume of damaged nervous tissue. The full spectrum of outcomes is possible: from complete clinical recovery to disability and death. Mixed forms of functional disorders occur in 20% of cases.

Dominant outcomes of perinatal CNS lesions:

• Attention deficit hyperactivity disorder (ADHD) — 22%. Based on reduced attention span and concentration, along with chaotic, non-target hyperactivity. Key diagnostic criterion: learning difficulties develop against the background of fully preserved intelligence.
• Cephalgic syndrome — 19%. Headaches generally represent a pathogenetic transformation of a previously suffered cerebrospinal-vascular dystonia syndrome.
• Speech delay — 18%. Frequently accompanies other manifestations.
• Neurotic disorders — 11%. Manifest as non-organic enuresis, tics, or sleep disorders (inversion).
• Motor and emotional sphere disorders — 5% each.

It is important to note that the onset of stuttering, tics, and neurotic disorders in children over 3 years of age has a clear connection to perinatal CNS lesions. Previous hypoxia leads to a delayed neurotransmitter system imbalance that manifests as the child grows older.

Differential diagnosis and management

The diagnosis is established based on a thorough history and typical clinical picture. The main difficulty in managing such patients is the risk of overdiagnosis due to the "pseudo-TORCH" syndrome. Genetically determined or spontaneous neural tube defects can completely mimic the consequences of perinatal CNS lesions.

To avoid errors, the 3-month diagnostic rule is applied. If a child receives adequate therapy for three months, but no positive dynamics in psychomotor development are observed, the primary diagnosis is called into question. In such situations, neuroimaging (brain MRI) must be performed, and the patient must be referred to a geneticist.

Class and exam questions

What else to study on this topic

• Clinical presentation and criteria for intracranial hemorrhages in newborns
• Specific diagnostics of TORCH infections
• Methods for managing cerebrospinal-vascular dystonia syndrome
• Drugs used to stop apoptosis and stimulate neuroplasticity
• Genetic syndromes mimicking the clinical picture of perinatal CNS lesions (pseudo-TORCH syndrome)

Other topics in «Chapter 2. Neonatology»

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