CC CJM | Neuro Assessment

80/20 Neurological Assessment & Physiology Summary

1. Structure & Cellular Biology

• Organization: The CNS consists of the brain, spinal cord, and CN I-II[1]. The PNS contains CN III-XII, spinal nerves, and the ANS[1].
• Cells & Myelin: Neurons conduct action potentials via saltatory conduction across nodes of Ranvier, accelerated by myelin[2]. Astrocytes form the blood-brain barrier and create scar tissue (gliosis) upon injury[2]. Oligodendrocytes myelinate CNS axons; Schwann cells myelinate PNS axons[2][3].
• Synapses: Neurotransmitters cross synapses to alter impulse transmission, using excitatory (glutamate) or inhibitory (GABA) pathways[4].

2. Pathways, Lobes & Perfusion

• Tracts: Ascending tracts carry sensory input (spinothalamic for pain/temp; dorsal columns for touch, vibration, position)[5]. Descending tracts (corticospinal) carry motor output[5].
• Motor Lesions: UMN lesions cause spasticity, hyperreflexia, and weakness[6]. LMN lesions cause flaccidity, hyporeflexia, and muscle atrophy[6].
• Cerebral Lobes: Frontal lobe controls cognition and motor speech (Broca's)[7]. Parietal lobe senses sensory data[7]. Temporal lobe handles hearing/language (Wernicke's); occipital processes vision[7].
• Perfusion: Anterior circulation stems from carotids; posterior from vertebral-basilar systems, joining at the circle of Willis[8].

3. Bedside Assessment

• Mental Status: Ongoing check of consciousness, orientation, cognition, and mood/affect[9].
• Cranial Nerves: CN III, IV, VI coordinate eye movements[10]. Pupil non-constriction (CN III) is an early sign of brain herniation[10]. Corneal reflex tests CN V/VII[11]. Gag reflex tests CN IX/X; a weak gag risks aspiration[12]. Midline tongue protrusion checks CN XII[12].
• Sensory & Proprioception: Test touch, pain, vibration, and digit position[13][14]. A positive Romberg test indicates posterior column dysfunction[15].
• Reflexes: Deep tendon reflexes are graded 0–5[15]. An extensor plantar response (toes up) signals an abnormal UMN lesion[16].

4. Diagnostics & Nursing Interventions

• CSF Analysis: Normal CSF is clear/colorless, with pressure of 60–150 mm H2O, protein of 15–45 mg/dL, and glucose of 40–70 mg/dL[16].
• Lumbar Puncture (LP) Care: LP is contraindicated in increased ICP due to risk of herniation[17]. Pre-procedure, check coagulation and place the patient in a sitting/side-lying flexed position[18][19]. Post-procedure, keep flat, monitor for headache, and push fluids[18].
• Aging: Aging causes cerebral atrophy, wider ventricles, reduced blood flow, and demyelination[20]. This leads to orthostatic hypotension, poor thermoregulation, and high fall risks[20][21].