Delirium and organic lesions
The development of cognitive impairment is often accompanied by emotional and behavioral disorders. Their pathogenesis is based on impaired neural network functioning between the limbic system, the prefrontal cortex of the frontal lobes, and subcortical structures (thalamus — thalamus, corpus striatum — corpus striatum).
Special attention is required for delirium, a condition manifesting with psychomotor agitation, sleep-wake cycle disturbances, illusions, and hallucinations. Its duration typically ranges from several hours to a day.
Main causes:
- Cerebrovascular disorders and traumatic brain injuries.
- Brain tumors and infectious processes.
Triggering factors:
- Decompensation of somatic pathology (cardiovascular, renal, endocrine), leading to dysmetabolic encephalopathy.
- Toxic and iatrogenic (drug-induced) effects.
- Withdrawal syndrome (abrupt cessation of alcohol or psychoactive substances).
Important clinical rule: in geriatric patients with acute or subacute memory and attention impairment, delirium must first be confirmed or ruled out.
Affective and volitional disorders
Dysmetabolic and organic lesions frequently cause mood disturbances that require precise differentiation.
Anxiety manifests as persistent, groundless worry, sleep disturbances, and symptoms of sympathetic nervous system hyperreactivity (tachycardia, sweating, rapid breathing). It is often accompanied by muscle tension, tremor, and hyperactive deep tendon reflexes. The pathogenesis is most commonly based on psychogenic factors.
Depression is diagnosed upon a persistent decrease in mood, loss of the sense of pleasure, and depressed state lasting for at least 2 weeks. It may present in a hidden ("masked") form, where cognitive or autonomic disturbances come to the forefront without subjective awareness of sadness. Severe forms with suicidal ideation require immediate psychiatric intervention.
Mania is characterized by hyperactivity, decreased need for sleep, and flight of ideas. Patients lack insight into their condition.
Volitional disorders:
- Apathy: reduced motivation for activity, blunting of emotions, and indifference.
- Abulia: inability to perform active actions while maintaining an understanding of their necessity.
Often they merge into a unified akinetic-abulic syndrome (in lesions of the medial prefrontal regions). In contrast, lesions of the lower (orbital) parts of the frontal lobe result in a psychomotor disinhibition syndrome (euphoria, impulsivity, tactlessness).
Examination of higher mental functions
To objectify cognitive deficit, a detailed examination of memory, gnosis, praxis, and speech is necessary.
Memory assessment
- Short-term: the patient is read 3 to 7 random digits or words for immediate repetition (norm is 5–9 items).
- Delayed: learning 5 semantically unrelated words (e.g., train, juice, caterpillar, engineer, horse). After a few minutes of distraction, the patient is asked to recall them, which assesses the transfer of information into long-term memory.
Examination of gnosis (recognition)
- Auditory: repetition of rhythms or recognition of simple melodies.
- Somatosensory: stereognosis (recognizing an object placed in the hand with eyes closed) and graphesthesia (recognizing numbers traced on the skin).
- Visual: recognition of faces, objects, and letters (detecting alexia — the inability to read).
- Visuospatial: drawing by a contour map or placing hands on a blank clock face.
Examination of praxis and speech Praxis is tested by asking the patient to perform symbolic gestures (saluting, shaking a fist) by command or imitation. A prerequisite is the absence of severe paresis. Speech is evaluated by its expressive component (fluency, presence of paraphasias, perseverations, and neologisms) and impressive component (understanding spoken questions and executing complex verbal instructions).
Briefly: answers to topical questions
Which neuropsychological scales are used for dementia screening?
Two main neuropsychological scales are used to screen for dementia and assess cognitive functions.
- Mini-Mental State Examination (Mini-Mental State Examination, MMSE) is used to assess orientation, attention, memory, calculation, speech, writing, reading, executive functions, and visuospatial sphere.
- Montreal Cognitive Assessment (Montreal Cognitive Assessment, MoCA) assesses executive functions, constructive praxis, memory, attention, speech, and abstract thinking.
What types of apraxia are distinguished in organic brain lesions?
The following types of apraxia are distinguished in organic brain lesions:
- Ideational apraxia — impairment in planning and initiating complex motor acts with the loss of understanding of their meaning and purpose.
- Ideomotor apraxia — impairment in performing actions by command, with imaginary objects, and imitating demonstrated movements.
- Constructive apraxia — difficulties in drawing spatial constructs; in dressing apraxia, difficulties may arise in matching parts of clothing and shoes.
- Motor apraxia — in severe form, the inability to perform basic movement sequences.
Oral apraxia, gaze apraxia, gait apraxia, and dressing apraxia are also distinguished.
What types of paraphasia exist in expressive speech disorders?
In expressive speech disorders, when evaluating content, fluency, intonation, and pronunciation correctness, two main types of paraphasia are distinguished.
- Literal paraphasias — pathological phenomena manifested as incorrect substitutions of individual letters in words.
- Verbal paraphasias — speech disorders representing incorrect substitutions of entire words.
Class and exam questions
What is the difference between an illusion and a hallucination?
Hallucinations occur in the complete absence of a real stimulus. Illusions, on the other hand, are distorted perceptions of a real object or stimulus.
What is "masked" depression?
This is a form of depression in which the patient does not experience overt, conscious mood lowering, but suffers from cognitive, sensory, and autonomic disorders (e.g., unexplained pain).
How is visuospatial agnosia assessed?
The patient is asked to draw the outline of a country with cities or determine the time on a drawn clock face that has hands but lacks numbers.
What else to study on this topic
- Neurochemical pathogenesis of affective disorders (role of dopamine, noradrenaline, serotonin)
- Pathological speech phenomena: detailed analysis of paraphasias and neologisms
- Specifics of hypomanic states in the structure of bipolar disorder
- Localization of lesions in psychomotor disinhibition syndrome
- Features of examining impressive speech in organic lesions
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