Chapter 60: Assessment of Neurologic Function

Assessment of Neurologic Function begins by dividing the nervous system into the central nervous system (CNS), which includes the brain and spinal cord, and the peripheral nervous system (PNS), encompassing the cranial and spinal nerves, as well as the autonomic nervous system. The core functional unit, the neuron, is detailed, explaining how impulses travel via dendrites and axons, with communication occurring across synapses mediated by neurotransmitters such as acetylcholine, dopamine, serotonin, and norepinephrine; it is noted that imbalances in these chemical messengers are implicated in numerous neurologic disorders, including Parkinson’s disease. Major brain structures are covered, defining the cerebrum, which handles high-level functions like concentration, memory, and motor control via its four lobes (frontal, parietal, temporal, occipital), alongside the cerebellum, vital for fine movement, balance, and position sense (proprioception). Protective structures like the skull, the three-layered meninges (dura mater, arachnoid, and pia mater), and the blood-brain barrier are discussed, as is the production and circulation of clear, colorless cerebrospinal fluid (CSF) in the ventricles, emphasizing that blockages can lead to hydrocephalus. Spinal cord function involves ascending (sensory) and descending (motor) tracts that often cross sides. The autonomic nervous system is compared, highlighting the sympathetic division (the “fight-or-flight” system) that predominantly uses norepinephrine for excitatory responses, versus the parasympathetic division, which primarily uses acetylcholine to control visceral functions during non-stressful conditions. Motor function is further characterized by the differences between upper motor neuron lesions (resulting in spastic paralysis and hyperactive reflexes) and lower motor neuron lesions (causing flaccid paralysis and muscle atrophy). Comprehensive neurologic assessment techniques are outlined, starting with the health history and common symptoms like vertigo, seizures, and pain, progressing to the physical examination, where the level of consciousness is identified as the most sensitive indicator of neurologic function. The physical exam includes evaluation of mental status and cognition, testing the twelve cranial nerves, assessing motor strength (using the five-point scale) and coordination (such as the Romberg test), and mapping sensory perception across dermatomes. Finally, the chapter details specialized diagnostic testing, including Computed Tomography (CT), Magnetic Resonance Imaging (MRI), Positron Emission Tomography (PET), Single-Photon Emission Computed Tomography (SPECT), Cerebral Angiography, Electroencephalography (EEG), Electromyography (EMG), and the procedure and post-care implications for Lumbar Puncture, including management of potential post-lumbar puncture headaches.