Examination of Cranial nerves VII to XII: Simple language and Video

Cranial Nerve I-VI examination 

VII Facial Nerve

Items needed for Facial Nerve Test 1.     Four sachets with 4 different items a.      Sugar powder b.     Salt powder c.     Sour (Vinegar) d.     Bitter (Grinded PCM/Metronidazole tablet) 2.     Gloves 3.     Guaze piece 4.     A bottle of drinkable water 5.     Four cards mentioning the words sweet, salty, sour and bitter in the language patient understands 1.     Ear buds/ Spatula

Confused with so many items. Here is a list of every thing you need to take for any CNS examination.

The motor function of the facial nerve is evaluated by looking for any gross features of weakness in the muscle of facial expression like deviation of mouth, loss of nasolabial fold or delayed blinking of the eyelid.

The patient is asked to wrinkle the forehead and look for symmetry.

The patient is asked to close her eyes, and close her eye against the examiners resistance which tends to pull upper and lower eyelids apart.

Ask the patient to smile and show their teeth.

Ask the patinet to whistle.

Ask the patient to blow their cheeks with air and hold it against the resistance given by the examiner.

The sensory function is evaluated by asking the patient to protude the tongue out and close the eyes. The anterior two third of the tongue is supplied by the chorda tympani  nerve and hence the four major tastes sweet, salt, sour and bitter to be evaluated. The solution containing each is prepared and using a new tongue blade or ear bud, the solution is applied over the tongue and the patient is asked to show the test in the cards given to him. After application of a solution, the patient is asked to thoroughly rinse the mouth with water.

VIII: Vestibulo Cochlear nerve

Items needed for Vestibulocochlear  Nerve Test 1.      Tuning Fork 256 Hz

The Cochlear function is assessed by using Tuning fork of 512 Hz is used to assess the hearing function.

Rennie Test: is performed by placing the vibrating tuning fork on the mastoid process and asking the patient to raise the hand if he stop hearing the sound. It assesses the Bone Conduction and the same tuning fork is brought and kept infront of the ear and ask if he still hears the sound.This measures air conduction(AC). If he hears the sound that AC>BC otherwise BC>AC. AC>BC is either normal or patient has sensorineural hearing loss. If BC>AC, it suggests conductive hearing loss.

Weber Test: Here the vibrating tuning fork is kept in the midline (glabella, vortex or even in between the incisors), the normal finding would be the sound heard in the midline. But if the sound is heard in one side then there is sensorineural hearing loss in the contralateral side and with conductive type of hearing loss loud sound is heard in affected side.

Some people fake hearing loss. Learn techniques to distinguish organic and non organic hearing loss. 

IX and X : Glossopharyngeal and Vagus Nerve

Items needed for Glossopharyngeal and Vagus Nerve Test 1.     Wooden spatula

Glossopharyngeal and vagus nerve supply the posterior oral cavity and oro pharynx and can be evaluated by observing the patient for any change in voice pattern especially hoarseness (Change in pitch seen in palatal paralysis) and history of aspiration or choking.

Ask the patient to open the mouth and   use a tongue depressor to visualize the tongue adeuately. Ask patient to pronounce “Ahh”. And look for differnce in palatal arch movement and deviation of uvula.

Inform patient that you are about to perform gag reflex and touch both the sides of palatal arch expecting for a gag to appear. The afferents are carried by the Glossopharynegeal nerve and efferent by motor component of glossopharyngeal and vagus nerve.

XI: Spinal accessory nerve

Test the sternoclaidomastoid muscle tone by asking the patient to turn head against the resistance applied over the left side of his cheek. Use the examiners right hand to apply resistance over the left cheek. Palpate the Right sided Sternoclaidomastoid for its tone and strength. And repeat the same for left side as well.

To check both the SCM simultaneously, place your hand in patients forehead and ask to bend forward. Now evaluate the SCM muscle for tone and strength.

XII: Hypoglossal Nerve

The Hypoglossal nerve supplies the muscle of the tongue and its function is examined by asking the patient to open the mouth and look for tongue deviation, wasting or any abnormal movements. The power and the tone is assessed by asking the patient to push the tongue against the buccal mucosa and palpating the tongue over the cheek to assess its strength.

Cranial Nerve I-VI examination 

Examination of Cranial nerves I to VI: Simple language and Video

Clinical Examination of Cranial Nerve I- VI(Part I) 

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I Olfactory Nerve: Sense of smell

Items needed for Olfactory Nerve Test 1.     Clove  2.     Coffee  3.     Soap

Commonly encountered objects can be used to make the patient smell the object and ask them about the smell of the object with each nostril closed individually and both eye closed.

Pungent smell producing substances such as onion and all are contraindicated because it can as well stimulate the trigeminal nerve to alter the interpretation.

Want to know what causes altered sensation of smell?

II Optic Nerve 

Items needed for Optic Nerve Test 1.     Pen 2.     Pen Torch 3.     Snellens chart 4.     Ischihara Chart/ Three thumbpin of color RBY 5.     White thumb pin

. In the examination of Optic Nerve, we perform the test to evaluate the following functions of optic nerve.Ophthalmoscopic examination for retina may not be feasible and come within the scope of this text.

Visual Acquity: It is evaluated using initially hand movement, finger counting and Snellens Chart which is kept at a distance of 6m from the patient and asked to identify the character in the chart with  one eyes closed at a time.

Visual Field: Visual Field is grossly evaluated using the confrontation test, where the eyes of both patient and examiner placed 1 m apart are closed on the same side. (Right for patient and left for the doctor and vice versa) and a moving finger or a pin with white colored head is brought towards the centre from the periphery. The patient is asked to tell the examiner whenever he sees the object. The finding is compared with the vision of examiner (Considering examiner as normal visual field).

Color vision: Ischihara Chart is the perfect tool to measure the color vision. In absence of that any three thumb pins with red, blue and yellow colors (Primary colors) can be used to evaluate the color vision.

Light reflex: The light is shown into the pupil being brought from the periphery and the constriction of ipsilateral pupil (Direct) and contralateral pupil (Indirect) is evaluated. A hand must be kept in between the two eyes to make sure that the light does not strike the contralateral pupil to stimulate its direct  light reflex. We need a torch light with white light to perform the light reflex. Swinging light reflex can be performed to look for RAPD (Rapid Afferent Pupillary Defect).

Know how pupils reacts to various substances, drugs and physiological condition.

Accommodation reflex and Convergence: A pointed object especially a pen or pencil is kept beyond the distance of 25cm and the patient is asked to focus upon its tip. The pen is brought towards the glabella and the accomodation reflex of convergence and miosis can be noted clinically. The afferent pathway for accommodation reflex is optic nerve and efferent is occulomotor nerve. So it tests both the nerve.

III/IV/VI: Oculomotor, trochlear, Adbucens nerve.
Accomodation reflex also forms the part of III IV VI Cranial Nerve examination.

Items needed for Extraocular muscle Examination 

1.     Pen

A pen or a sharp tip object is taken and the patient is asked to focus on the tip and follow the pointed end without turning their head. The object is moved in a fashion to make a large shape of H within his visual field and the movement of the eye is evaluated for monoocular and binocular vision.

V: Trigeminal Nerve

Items needed for Trigeminal Nerve Test 1.     Cotton 2.     Pin / Tooth pick 3.     Reflex Hammer The trigeminal nerve is evaluated for both its motor and sensory function. Must Have instruments needed to perform CNS examination.

The motor branch innervates the muscle of mastication and temporalis muscle. The strength of trigeminal nerve is evaluated by asking the patient to clench his teeth and the volume and tone of muscles evaluated by palpating the strength of masseter and temporalis.

On asking the patient to open the mouth, the chin will be deviated towards the paralysed side. Similarly asking the patient to move the mandible against the resistance of hand, the paralysed side will not move laterally.

Jaw jerk is a muscle stretch reflex carried out by keeping the mouth partially open and index finger of the examiner placed over the jaw. A reflex hammer is used to tap the finger placed over the mandible directed downward.

Sensation of the trigeminal nerve is grossly evaluated over the ophthalmic, mandibular and maxillary division. With the eyes closed, the patient is asked to describe whether one or both side of their face is touched and if they are different. Use a cotton or the pulp of the finger to evaluate the fine touch. Similarly use a tip of blunted pin or tooth pick to evaluate pin prick.

Corneal reflex and conjunctiva reflex both have a afferent pathway carried by the trigeminal nerve and efferent pathway by the facial nerve. So, the patient must be described what is being done and a twisted end of cotton is brought to the limbus or conjunctiva respectively from the lateral canthus and touched softly. A brisk reflex presents with blinking of eyelid instantaneously and bilaterally.

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