Chapter 16

The neurological exam is a clinical assessment tool used to determine specific parts of the central nervous system (CNS) affected by damage or disease.
The exam can be performed quickly—sometimes in as little as 5 minutes—to establish neurological function, crucial in emergency settings for effective treatment and recovery potential.
The exam comprises several subtests organized into five major sections:
- Mental Status Exam: Assesses higher cognitive functions such as memory, orientation, and language.
- Cranial Nerve Exam: Tests function of the 12 cranial nerves, assessing related central and peripheral structures.
- Sensory Exam: Tests sensory functions associated with spinal nerves.
- Motor Exam: Tests motor functions associated with spinal nerves.
- Coordination Exam: Tests ability to perform complex and coordinated movements.
The gait exam is frequently considered a sixth exam, focusing specifically on motor function during walking, as it embodies coordinated movement.

Localization of Function: Specific locations within the CNS are responsible for distinct functions, illustrated through the neurological exam.
- Example: Cognitive functions assessed in the mental status exam relate to structures within the cerebrum, particularly the cerebral cortex.
- Language functions generally localize to the left hemisphere, particularly between the superior temporal lobe and posterior frontal lobe, with connections through the inferior parietal lobe.

Mental Status Exam: Assesses functions related to the cerebrum.
Cranial Nerve Exam: Pertains to nerves linking the diencephalon and brain stem, including olfactory connections to the forebrain.
Coordination Exam & Gait Exam: Primarily evaluate cerebellum functions.
Motor & Sensory Exams: Associated with the spinal cord and connections via spinal nerves.

A quick neurological assessment in emergencies allows for effective localization of deficits and informs immediate therapeutic decisions.
For example, in an emergency, a patient exhibiting sensory disturbances may receive aspirin to mitigate blood clot risk while awaiting formal imaging like a CT scan.

Damage to the nervous system can be focal or widespread, often resulting from circulatory problems.
Neurons are sensitive to oxygen deprivation; even short term (1-2 minutes) can result in deterioration and potential cell death (permanent damage).
Stroke (CVA): Loss of blood flow in the brain, categorized principally as:
- Ischemic Stroke: Caused by blockage/narrowing of blood vessels; could result from an embolus (blood clot or fat deposit) or hypovolemia (decreased blood volume).
- A Transient Ischemic Attack (TIA) is a temporary episode of ischemia, resolved within 24 hours.
- Hemorrhagic Stroke: Involves bleeding in the brain due to ruptured vessels, leading to a pressure buildup that can damage local tissue and compromise blood flow.

Blood accumulates in brain tissue, leading to:
- Physical pressure on brain structures causing loss of functions.
- Possible breakdown of the blood-brain barrier leading to edema.
Lesions due to hemorrhagic events can cause widespread neurological dysfunction.

There are various infectious, traumatic, or neurodegenerative disorders.
Neurodegenerative Diseases: Include Alzheimer's disease, Parkinson's disease, Huntington's disease, and others, resulting primarily from neuronal death or myelin degeneration (in MS).
- Causes of degeneration are varied, with some genetically inherited, while others involve complex pathways not fully understood (e.g., Alzheimer's).
Developmental Disorders: Can lead to neurological functions differing from norms caused by past defects that interrupt normal CNS development.

Cognitive abilities include:
- Orientation and Memory: Measures awareness of time, place, and identity (e.g., asking patients to state their name or the current date).
- Language and Speech: Assessed through instructions and descriptions.
- Sensorium: Assesses perception status.
- Judgment and Abstract Reasoning: Involves problem-solving abilities and understanding proverbs.

Memory involves various brain structures:
- The hippocampus and nearby structures in the medial temporal lobe are crucial for forming new memories.
- Case Study: Patient HM, who underwent a lobectomy but could not create new memories (anterograde amnesia) while able to recall past events (retrograde amnesia).
Memory types include:
- Episodic Memory: Individual events and experiences.
- Procedural Memory: Skills and actions.
- Short-term (Working) Memory: Involves the prefrontal cortex more than the medial temporal lobe.

Two critical regions involved with language:
- Broca’s Area: Controls speech production; damage leads to expressive aphasia (difficulty in word formation).
- Wernicke’s Area: Involved in language comprehension; damage leads to receptive aphasia (inability to understand spoken language).
Conduction Aphasia: Damage to white matter tracts connecting Broca’s and Wernicke’s areas affecting the production of coherent speech despite intact comprehension.

The sensorium includes areas that receive and interpret sensory stimuli, with cortical regions critical for sensory perception. Planting ideas about:
- Praxis: Ability to perform tasks based on verbal instructions without demonstration.
- Gnosis: Relates to recognizing and naming objects based solely on sensory information, assessed through tasks like stereognosis (identifying objects by touch) and graphesthesia (identifying writing on the skin).

The motor and coordination sections of the neurological exam evaluate:
- Muscle strength through resistance exercises.
- Movement types (intention tremors and rebound responses) through tests testing planning and coordination of movements:
- Tests include finger-to-nose and rapid alternating movements.

Ataxia: Movement disorder referencing loss of coordination resulting from cerebellar damage; can also pertain to sensory deficits causing balance issues.
Assessment methods focus on posture and gait, where specific tests indicate cerebellar function and proprioception.

Knowledge of the structures and functions accessed through the neurological exam is crucial, as deficits can arise from various causes, underscoring the importance of comprehensive and timely assessment to optimize outcomes for neurological patients.