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- The neurological exam allows for detection of symptoms that are indicative of underlying neurological pathologies and abnormalities. The exam is also necessary to determine the range of disability in neurological function.
- A properly conducted neurological examination allows for the localization of the pathology to particular areas in the central and peripheral nervous system.
- The examination serves as a necessary preliminary step to determine which diagnostic test should be prescribed.
- Sensory dysfunction as a consequence of systemic illness can also be screened through neurological examinations.
The key parts covered in the neurological exam include:
- Cranial Nerves
- Muscle strength, tone, and bulk
- Sensory Function
- Mental status testing
There are twelve cranial nerves that control different aspects of facial functions. Damage to different nuclei or different sections of some nerves can lead to the presentation of different signs and symptoms.
Cranial Nerve 1 (Olfactory Nerve)
There is little value in routinely testing olfaction as it is uncommon to detect an abnormality. Hence testing olfaction is usually omitted from a clinical exam unless there are specific clinical suspicions. A subfrontal tumor such as a meningioma may cause unilateral anosmia. Subfrontal meningioma can cause bilateral anosmia. Olfactory nerve fibers pass through the cribriform plate; hence head injury resulting in fracture of the cribriform plate can lead to permanent bilateral anosmia. Anosmia is commonly neurodegenerative, occurring particularly in Lewy body disease. Olfaction is also tested when Kallman’s syndrome is suspected.
- Before starting the examination, the patency of the nostrils and the ability of the patient to smell should be checked.
- The patient is first told to close their eyes.
- Test each nostril separately.
- One nostril should be closed while the other is being tested.
- Irritating smells like ammonia should not be used.
- Present common smells like peppermint, soap, clove oil, etc.
CN II: Optic Nerve Testing
Testing the optic nerve consists of several components: visual acuity, color vision, visual field, pupillary examination and fundus examination.
- To assess visual acuity, a Snellen’s chart is used, and each eye is tested separately.
- Ask the patient to read the lowest possible line or successively lower lines to identify efficiently which line can be read with 100% accuracy.
- If the patient cannot read even the topmost line, show him your hand and ask him to count fingers.
- If the patient fails, wave your hand and ask if the patient can detect the hand movement.
- If the patient fails, direct light into his/her eyes to check if the patient can perceive the light.
Acquired unilateral loss of color vision is a characteristic feature of optic neuropathy, and loss of color vision can occur even if visual acuity is intact. Hence, testing color vision using Ishihara test chart books may be a sensitive bedside test for mild optic neuropathy.
Visual field defects in one eye indicate a retin