Cranial Nerve Examination | Clinical Skills OSCE Guide | Dr Gill

The brain stem consists of three levels (medulla, pons, and midbrain) each associated with specific cranial nerves and reflexes: the medulla contains cranial nerves IX-XII and is tested using the gag reflex; the pons contains cranial nerves V-VIII and is tested using the corneal reflex; the midbrain contains cranial nerves III-IV and is tested using the pupillary light reflex. Each level has distinct vascular supply (vertebral artery for medulla, basilar artery for pons and midbrain) and structural landmarks visible in cross-sections.

The pupillary light reflex is a four-neuron reflex arc where light detected by retinal ganglion cells sends signals via the optic nerve to the pretectal nucleus in the midbrain, which then activates the Edinger-Westphal nuclei; these nuclei project to the ciliary ganglia, whose postganglionic fibers innervate the sphincter pupillae muscle to cause pupil contraction, and this reflex causes bilateral pupil constriction when light is shown in either eye.

The corneal light reflex is tested by shining a penlight in the patient's eyes and observing that the light reflects from both corneas in the same location. The pupillary light reflex is tested by shining light into one eye and observing that both pupils constrict equally and reactively. These tests assess cranial nerves II, III, and V.

The pupillary light reflex involves melanopsin-containing retinal ganglion cells detecting light and sending signals through the optic nerve to the pretectal nucleus in the midbrain, which then activates the Edinger-Westphal nuclei to trigger parasympathetic fibers via the oculomotor nerve, causing the sphincter pupillae muscle to constrict the pupil and the ciliary muscle to thicken the lens for near vision; conversely, sympathetic fibers from the superior cervical ganglion cause the ciliary muscle to relax, zonules to tighten, and pupil to dilate for distance vision, with both responses working together to optimize vision under varying light conditions and object distances.

The pupillary light reflex involves the direct constriction of the illuminated pupil and consensual constriction of the opposite pupil, testing the optic nerve (CN II), midbrain, and oculomotor nerve (CN III); the accommodation reflex involves three coordinated responses—convergence (eyes turning inward), constriction (pupil narrowing), and contraction (lens becoming fatter)—testing the optic nerve, visual cortex, frontal cortex, and oculomotor nucleus, both somatic motor and parasympathetic components.

This video provides a comprehensive guide to the essential items required for RACP divisional clinical examinations, including a stethoscope (Littman cardiology IV), Queen's square tendon hammer, stopwatches (at least 2, no smartwatches), tape measure, eye covers with pinhole, wooden spatula, tuning forks (128Hz for vibration sense, 512Hz for Rinne/Weber), hat pins, jar with lid, key and lock, shirt sleeve with button, cotton wool, neurotips, bulldog clips, system cards, A4 paper, Snellen chart, long cotton swabs, 10g nylon monofilament, pen torch, ballpoint pen, sticky labels, and ophthalmoscope/fundoscope. The presenter emphasizes that printed materials like Ishihara plates and Boston cookie jar are no longer permitted, and notes that ophthalmoscopes are typically provided in the clinic room if needed.

This section covers essential OPD ENT instruments. The Bullseye lamp produces yellow light and requires another light source, making it cumbersome; modern practice prefers battery-operated LED lights worn on the head with a pinhole, allowing focused illumination and freeing both hands. The ophthalmoscope visualizes the tympanic membrane with its speculum. The oral speculum, used with a headlight, allows free hands for procedures like wax removal. The Jobson Horn ring curette with probe has two functions: a ring curette for removing foreign bodies and wax from the ear canal, and a probe for examining polyps or clearing discharges. Hartmann's tuning fork (stainless steel, 256/512/1024 Hz) is used for hearing tests; 512 Hz is preferred as it falls in speech frequency with no tone decay. Frequencies are multiples of 8 (octaves). Tests include Rinne for conductive loss, Weber for lateralization, and ABC for malingering detection.

Ophthalmoscope is a system of lenses and mirrors with light sources enabling visualization of eye interior structures, with magnification from -20 to +40 diopters. Strabismus scope detects strabismus using a one-way mirror. Visual acuity is measured using Snellen chart (letters read from 20 feet, recorded as fraction like 20/20), Tumbling E, HOTV chart, and LEA symbols. Alternative tests include broken wheel test and near vision testing with Rosenbaum chart. Tuning forks are used for auditory function screening, with 512 Hz forks for auditory evaluation and 500-1000 Hz forks for normal speech range hearing loss. Percussion hammer tests deep tendon reflexes with rapid wrist snap. Neurologic hammer has additional features for sensory perception testing. Transilluminator uses narrow beam light to differentiate between air, fluid, and tissue in body cavities.

Medical students must recognize their role as learners and train with actual patients to develop clinical skills. Professionalism must be exhibited at all times, even when feeling unprepared. Essential equipment includes precision scale, tape measure, examining bed, drape, Snellen chart, vital signs equipment, cotton, tuning fork, otoscope, ophthalmoscope, penlight, and stethoscope. The examination environment requires adequate lighting and organized paraphernalia placement in sequence of use. Patient comfort and privacy must be maintained throughout, with drapes always used and consent obtained before examination. The examination should be comprehensive to master the skill, prioritizing patient comfort and avoiding unnecessary position changes.

The cranial nerve examination concludes with tuning fork, facial sensation, and visual testing: (1) Tuning fork test for hearing assessment (Weber and Rinne tests), (2) Facial sensation testing using cold stimulus to trigeminal nerve distribution, (3) Visual acuity testing using Snellen chart with both eyes separately, (4) Color recognition testing, (5) Shape recognition testing. These tests complete the cranial nerve examination by assessing optic nerve (II), trigeminal nerve (V), and auditory function.

All OSCE communication stations follow a consistent structure regardless of the topic. The fixed steps include: (1) Self-introduction stating your name and profession, (2) Identifying and confirming the patient's identity, (3) Assessing the parent's educational level to tailor communication, (4) Using appropriate body language and eye contact, (5) Demonstrating empathy especially in difficult situations, (6) Explaining the patient's condition clearly, (7) Explaining the source of medical information, (8) Asking if anyone else should be present, and (9) Checking understanding after each piece of information. These steps must be memorized and applied consistently across all communication tasks.

In MRCEM OSCE communication skills stations, candidates should follow a structured approach: read the scenario, knock and enter, greet people, wash hands, introduce yourself, and confirm the other person's identity; then start the conversation by inviting the other person to speak, listen actively without interrupting, show sympathy when appropriate, use silence effectively when delivering difficult information, and finish by asking if they have other questions, offering help, thanking them, and leaving; key communication principles include staying calm, avoiding aggression, never giving false information, and using proper silence when delivering shocking news.

The OSCE consists of 30 total stations, with 10 being exam stations that will appear in the actual examination. Each station follows a specific time structure: 2 minutes for reading the scenario, 8 minutes for performing the task, and 2 minutes for preparation outside the station. The total time per station is 12 minutes. The OSCE uses a 100-point scoring system divided into three components: 25 points for communication (first part), 50 points for the body/clinical task (main part), and 25 points for closing the station (final part). To pass, students must score above 50%. When entering an OSCE station, students should close the door to maintain patient privacy, check that the scene is safe to proceed, and perform hand hygiene. These actions are critical for the 25-point communication component. Students should verbalize each action as they perform it. After hand hygiene, students should introduce themselves to the patient by stating their name and role. In Australian and New Zealand nursing protocols, this introduction is mandatory and very important. Students should acknowledge the patient's condition and offer comfort measures. The 25-point communication component should be completed in approximately 1 minute maximum. Before performing any clinical task, students must check the patient's identification by asking for name, date of birth, and MR number, then verifying against the patient's file. Students should also check for allergies by asking 'Do you have any allergies?' and verifying against the patient's chart.

Successful OSKI performance begins with proper introduction and patient safety protocols. Always use hand gel first as a tick box for extra points. Introduce yourself and your role professionally. Confirm patient identity by checking name, date of birth, and wristband, comparing any provided documents to the wristband. Explain what you will do and gain consent. Clarify patient questions to make them comfortable. Ensure appropriate positioning and offer a chaperone for intimate exams. Review any provided documents like drug cards to understand medication history and allergies. Check bedside equipment as it may be relevant to the scenario.

Effective OSCE communication requires: (1) Avoid 'good morning' and use 'hello' instead, as exam times vary; (2) Always confirm patient identity by name and age; (3) Set an agenda by confirming why the patient is there; (4) Avoid phrases like 'nice to hear' when delivering bad news; (5) Use 'relationship' instead of 'marriage' to avoid assumptions; (6) Complete information gathering before breaking bad news; (7) Avoid false reassurance and sugarcoating.