CLINICAL CORRELATIONS

Ataxia

A clinical disorder of the cerebellum characterized by lack of coordination, delay in initiation of movement, and poor execution of movement sequences

Dysdiadochokinesia

The inability to perform rapid alternating movements, a sign of cerebellar dysfunction

Rebound phenomenon

The inability to stop a movement, a sign of cerebellar dysfunction

Gait Ataxia

A type of ataxia affecting lower limbs, often seen with anterior lobe cerebellar lesions, characterized by uncoordinated, clumsy movements

Tandem stance

A test involving walking heel to toe, used to assess gait ataxia and cerebellar function

Intention tremor

A tremor that appears and increases in magnitude as the affected hand or foot approaches a target, a sign of posterior lobe cerebellar syndrome

Nystagmus

Rapid, uncontrollable movements of the eye that can be a sign of a cerebellar problem

Oscillopsia

A visual symptom where patients with nystagmus see the world as "jumping" or moving

Sensory Ataxia

Ataxia caused by a peripheral nervous system problem where decreased sensation requires stepping with more effort to feel the floor

Chronic alcoholism

A condition that can cause permanent cerebellar damage and ataxia due to significant loss of Purkinje cells

Anterior lobe syndrome

A finding characterized by a certain group of signs and symptoms, such as gait ataxia, that can result from various causes like genetic factors, autoimmune conditions, or stroke

Dysarthria

Difficulty speaking, potentially seen in patients with cerebellar problems, characterized by trouble speaking or enunciating words

Dysmetria

The inability to control the distance, speed, and range of motion during movement, potentially indicated by difficulty with tests like touching nose to finger

Symptoms of BG Disease

A section listed in the outline discussing the clinical manifestations of conditions affecting the basal ganglia

Cognition

The process of acquiring knowledge and understanding using thought, experience, and sensory information

Dementia

A general term for a marked decline in memory, intellect, or personality severe enough to interfere with daily life, not a normal part of aging

Clinical dementia

A group of non-specific symptoms characterized by a marked decline in memory, intellect, or personality severe enough to interfere with one’s daily life and social skills

Dementia ABC

A mnemonic for the characteristics of dementia: ADL decline, Behavioral changes, Cognitive dysfunction

Mild cognitive impairment (MCI)

An intervening stage between aging and dementia, characterized by cognitive decline on testing and history but without functional impairment

Subjective cognitive impairment or decline (SCI / SCD)

A condition characterized by subjective decline in cognitive function but with satisfactory objective testing results

Anterograde Amnesia (AA)

The inability to store new information, usually new biographical events

Retrograde Amnesia (RA)

Memory impairment affecting information acquired in the past

Medial temporal lobe (MTL) damage

The severity of anterograde and retrograde amnesia is related to the severity of damage to this brain region

Forgetfulness

Consistent or persistent and worsening instances of this are never part of normal aging

Hippocampal atrophy

A change in brain structure that can be found on imaging and is associated with cognitive impairment and Alzheimer’s disease

Alzheimer’s Disease (AD)

A disease characterized by an exaggerated functional decline, impacting the Default Mode Network the most, and accelerating aging

Amyloid deposition

The Default Mode Network is especially vulnerable to this substance, which is associated with Alzheimer's disease and may be increased by chronic lack of sleep

Frontotemporal dementia (FTD)

A type of dementia where dysfunction in the Salience Network (SN) is observed

Hallucinations and Delusions

Symptoms involving disruption in top-down and bottom-up processing, associated with dysfunction in the Default Mode Network (DMN), Dorsal Attention Network (DAN), Ventral Attention Network (VAN), and sensory brain networks

Depression

A neuropsychiatric condition where the Default Mode Network (DMN) can be overactive and that can be a risk factor for dementia

Manic state

A state where the Sensorimotor Network (SMN) can be overactive

Obsessive-compulsive disorder (OCD)

A condition where overactivity of the Central Executive Network (CEN) is implicated

Alcoholism, drug use, uncontrolled hypertension, diabetes, and high cholesterol

Conditions that can expedite brain aging

Overlap between depression and dementia

A clinical observation where memory symptoms can occur in major depressive disorder

Agnosia

A perceptual-motor condition involving the inability to recognize sensory inputs despite intact sensory pathways

Agraphesthesia

The inability to identify letters or numbers traced on the skin, in the setting of an intact sensory system

Astereognosis

The inability to identify 3D objects by touch despite prior experience with that object and an intact sensory system

Asomatognosia

The inability to identify parts of the body

Prosopagnosia

The inability to identify faces in person or in photos, associated with lesions in the inferomedial temporo-occipital region, specifically the fusiform gyrus

Neglect or Inattention

A perceptual-motor condition where awareness of one side of space is impaired

Sensory inattention

A form of neglect where attention to sensory stimuli is impaired

Anosognosia

A perceptual-motor condition involving unawareness of one's own deficits

Apraxia

A perceptual-motor condition involving the inability to perform learned motor movements despite intact motor pathways

Tongue Apraxia

A neurological disorder affecting brain pathways for speech production, causing impaired performance on commands, particularly for the tongue

Aphasia / Dysphasia

Acquired communication disorders affecting the ability to understand or express language

Broca’s Aphasia

An expressive or motor aphasia characterized by slow, poorly articulated, labored speech with a loss of propositions

Global Aphasia

A severe type of aphasia where comprehension is affected

Dysprosody

An acquired communication disorder affecting intonation, melody, pauses, and phrasing of speech, typically processed in the right hemisphere

Expressive dysprosody

A form of dysprosody where the patient has monotonous, flat, and emotionless speech

Receptive dysprosody

A form of dysprosody where the patient is unable to interpret the emotion in a phrase spoken by others

Consciousness

A state of awareness of self and environment that gives significance to stimuli from the internal and external environment, composed of arousal and cognitive functions

Altered Consciousness

Different complex and variable patterns of arousal and awareness compared to the normal state

Clouding, Delirium

Acute patterns of altered consciousness

Obtundation, Stupor, Coma, Locked-in

Subacute or chronic patterns of altered consciousness

Metabolic Coma

A type of coma that is reversible if the inducing factors are identified and addressed

Structural Coma

A type of coma resulting from structural brain damage

Encephalitis

An example of bilateral cerebral affectation that can cause neurologic coma

Hypoglycemia, Hyponatremia, Hypoxia

Examples of non-neurologic causes of coma

Locked-in syndrome

A condition where the Basis Pontis is usually severed, affecting ventral tegmental areas and pontine fibers, leading to paralysis of facial and extremity muscles while consciousness is preserved

Glasgow Coma Scale (GCS)

A scale used to assess the consciousness of patients based on scoring for eye opening, verbal response, and motor movements

Brainstem reflexes

A set of reflexes used to assess brainstem function in comatose patients, including Pupillary Light, Oculocephalic, Vestibuloocular, Corneal, Auditopalpebral, and Gag reflexes

Brainstem failure

The state indicated when all brainstem reflexes are not present

Glasgow Coma Scale score of 3

The lowest possible score on the GCS, indicating deep coma

Glasgow Coma Scale score of 15

The best possible score on the GCS, indicating full consciousness

CN V(I) (Afferent) and CN VII (Efferent)

The afferent and efferent limbs of the corneal reflex

Sleep-onset REM periods (SOREMPS)

REM sleep periods that happen within 15 minutes of falling asleep, the basis for the idea of a "power nap"

Disrupted sleep

A common feature in elderly persons with dementia and Alzheimer’s, which could be a symptom or a contributing factor

Pain

A sensation resulting from stimuli translated into electrical depolarizations in nerve endings

C fiber and A-delta fiber (Group III fibers)

The two main types of afferent fibers that respond maximally to nociceptive stimuli

Anesthesia

Increased sensitivity and lowered threshold to painful stimuli, opposite of the layperson's term for lack of sensation

Agraphesthesia

Inability to identify letters/numbers traced on skin

Astereognosis

Inability to identify 3D objects by touch

Thalamic nuclei destruction

Leads to loss of sensation on the contralateral side of the body

Astereognosis affecting DCML pathway

Inability to identify a paper clip placed on the hand with eyes closed suggests this condition and affected pathway

Sensory Ataxia

Ataxia caused by a peripheral nervous system problem

Vibration sense

This specific sense is the most affected in the aging brain

Emmetropia

Normal eyesight, where light focuses precisely on the retina

Hyperopia

Farsightedness, where light focuses behind the retina, corrected with convex lenses

Myopia

Nearsightedness, where light focuses in front of the retina, corrected with concave lenses

Presbyopia

Aging-related vision problem due to loss of elasticity of the lens, corrected with bifocals

Astigmatism

Refractive error due to irregular curvature of the cornea or lens

Homonymous contralateral superior quadrantanopia

A visual field deficit resulting from a lesion in the optic radiations affecting the Parietal Lobe

Pigment epithelium

The layer in the retina responsible for absorbing stray light and where photoisomerization occurs

Hyposmia or Anosmia

Decreased or complete loss of smell, which can be caused by a fracture of the cribriform plate

CN I (olfactory nerve)

The cranial nerve that carries information from olfactory receptor cells to the olfactory bulb, containing slow-conducting unmyelinated C fibers

CN V (trigeminal nerve)

The cranial nerve that detects noxious or painful olfactory stimuli, such as ammonia

Sympathetic NS, Parasympathetic NS, Enteric NS

The main subdivisions of the ANS

Parasympathetic nervous system

Also known as the craniosacral division of the ANS, referred to as the "rest and digest" system

Adrenal gland

An organ controlled by sympathetic preganglionic neurons located in spinal levels T4-T12

Hypothalamus

A central control area for autonomic function, containing centers for satiety and feeding

Acetylcholine (ACh)

An excitatory neurotransmitter mediating synaptic transmission in the CNS, PNS, and ANS, the primary NT of ANS preganglionic fibers

Nicotinic receptors

A class of ACh receptors found on plasma membranes of dendrites and cell bodies of both sympathetic and parasympathetic postganglionic neurons, chromaffin cells of suprarenal medullae, and the motor end plate

Muscarinic receptors

A class of ACh receptors found on plasma membranes of all effectors innervated by parasympathetic postganglionic axons (smooth muscle, cardiac muscle, glands)

Inhibitors of degradation of ACh

Medications used for patients with dementia due to ACh's role in learning and memory

Acetylcholinesterase

The enzyme that degrades ACh to acetyl CoA and choline, inhibited by drugs like pyridostigmine

Mild cognitive impairment, memory lapses, subjective cognitive impairment

Conditions associated with a minimal reduction in acetylcholine transporter levels, leading to less ACh in synapses

Dopamine, Serotonin, Norepinephrine

Neurotransmitters considered important for emotion and behavior

Monoaminergic system

A system of neurotransmitters, including dopamine and norepinephrine, which when increased (e.g., by methamphetamines) have been correlated with euphoria

Serotonergic medications

Substances given to patients with depression that seem to improve their expression of happiness

Insula

A brain structure involved in the bodily experience of emotion and acting as a source of disgust related to taste information