Directed Neurological Examination MOTOR

First, the clinician should observe the patient at rest for symmetry and the presence of any involuntary movements (e.g., fasciculations, tics). Signs of facial weakness include flattening of the nasolabial groove, slower blinking, and loss of facial wrinkles. Next, clinicians should check the amount of voluntary motion in each of the five peripheral branches by having the patient perform the following: (1) temporal--raise the eyebrows, wrinkle the brow; (2) zygomatic--close the eyes gently, and with maximal effort try to keep the eyes closed while the examiner attempts to open them; (3) buccal--smile, show teeth, puff out the cheeks; (4) mandibular--pout, purse the lips; (5) cervical-- sneer. The clinician should determine if the patient exhibits Bell's phenomenon, which is an upward and outward rolling of the globe when eyelid closure is attempted. When there is incomplete closure, this phenomenon protects the cornea by placing it under the upper eyelid and moving it laterally. While testing the facial expressions, synkinesis should be sought, which is unintentional motion of a group of muscles when another group is voluntarily contracted (e.g., contraction of the eyelid during smiling). To differentiate a central palsy, clinicians should look for sparing of upper facial motion and for preservation of emotional facial expressions (e.g., surprise, pain). Both sides of the face should be examined closely to rule out bilateral involvement. A change in loudness perception suggests involvement of the nerve branch to the stapedius muscle. This hyperacusis can be confirmed subjectively by checking auditory function with finger rub or tuning forks and can be documented objectively by acoustic reflex testing during an audiometric evaluation.

Examiners must be careful not to confuse transferred contralateral motion with weak motion of the involved side. For example, the contralateral frontalis can create some wrinkles in the forehead of the involved side, and contralateral midfacial muscles can cause motion of the involved side. To prevent confusion, the examiner should cover the contralateral side to focus solely on the involved side before comparing the two sides. In addition, by holding the skin of the uninvolved side against the facial skeleton, midfacial motion from the contralateral side can be minimized. Likewise, examiners should not confuse active eye closure with the normal, gravity-assisted passive closure of the eyelids, which occurs after the levator palpebrae superioris is relaxed. [18]


The response to solutions of the four fundamental tastes (sweet--sucrose, sour--citric acid, salty--sodium chloride, and bitter--quinine sulfate) should be evaluated in the anterior two thirds of the tongue. The patient should be instructed not to eat or smoke for several hours before testing. Before test solutions are applied, the mouth is rinsed with distilled water. Then, using cotton swabs, a test solution is placed on the lateral, anterior tongue. The patient should be instructed to state whether the solution is sweet, sour, salty, bitter, unknown, or without taste. Between test solutions, the mouth should be swished with distilled water. Each side should be tested separately. To eliminate olfaction, patients should pinch their nose or hold their breath during the testing.

The somatic sensation of the posterolateral external ear canal and concha should be tested in the usual fashion (cotton wisp, pinprick, and other) and the results compared with the sensation of the surrounding areas and with the contralateral side.


Several reflexes related to facial nerve function can be tested, including the following: (1) corneal reflex--tactile stimulation of the cornea normally causes both eyes to blink simultaneously. The afferent limb is from CN V (ophthalmic division), whereas the efferent limb is from CN VII (motor root). Depending on the reflex patterns elicited, one can differentiate between a CN V or CN VII lesion. For example, if right-sided corneal stimulation does not cause both right and left eyelid closure, but left-sided stimulation does, there is a right CN V deficit. Similarly, if both right- and left-sided corneal stimulation cause the left eye to blink, but not the right, there is a right CN VII lesion. (2) Orbicularis oculi reflex--the examiner pulls the skin lateral to the lateral canthus with the thumb and index finger and then taps the thumb lightly with a reflex hammer, resulting in orbicularis oculi contraction. This stretch reflex shows hyporeflexia in peripheral palsy and hyperreflexia with central palsy. (3) Blink reflex--normally every 2 to 15 seconds there is spontaneous bilateral blinking. (4) Auditory palpebrae reflex--sudden, unexpected loud sound causes a single bilateral eyelid closure. Sudden bright lights also cause reflex eyelid closure. (5) Palmomental reflex-- tapping or stroking of the palm causes contraction of the ipsilateral mentalis muscle. This pathological reflex is seen with pyramidal tract disease and helps diagnose a central palsy. Another reflex seen with central lesions is the snout reflex, in which tapping of the lips causes pursing of the lips. (6) Other reflexes associated with CN VII include the glabellar (tapping of the glabella causes both eyes to blink), supraorbital (tapping of the supraorbital ridge causes the ipsilateral eye to blink), nasolacrimal (irritative or painful nasal stimulation causes tearing), nasal (ipsilateral facial contraction after tickling of the nasal mucosa), and oculogyric-auricular (contraction of the auricular muscles after lateral gaze). y


Infranuclear lesions can cause a reduction in ipsilateral tear production if they occur at, or proximal to, the geniculate ganglion. The Schirmer test provides a quantitative evaluation of tear production. Sterile strips of filter paper are folded into the shape of a hook and placed into each lower conjunctival fornix. After 5 minutes, the degree of wetting is measured and compared between sides. A unilateral reduction of more than 30 percent of the total amount of lacrimation of both eyes or bilateral tearing of less than 25 mm is considered significant. This test consists of an afferent limb (CN V) and an efferent limb (CN VII); however, unilateral corneal stimulation from the filter paper should cause bilateral, equal lacrimation. Therefore, because both eyes are tested simultaneously, a unilateral CN V lesion does not result in decreased tearing. y , y

A lesion distal to the geniculate ganglion may result in excessive tear production. If there is corneal irritation resulting from poor eye closure, lacrimation may be increased. In addition, ectropion resulting from orbicularis oculi weakness and loss of facial tone disrupts the normal flow of tears. Instead of being circulated by blinking and cleared by the canaliculi (aided by the pumping action of the periorbital muscles), tears pool in the lower conjunctival sac and spill over the lower lid margin.y

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