CNS Examination in children I Cranial Nerve Examination (I to VI) in children | Pediatrics

Summary

This video provides a detailed guide on performing the cranial nerve examination in children, focusing on cranial nerves I through V. It explains age-appropriate techniques for testing smell, vision, ocular movements, pupillary reactions, and facial sensations. The video emphasizes proper procedures, including visual acuity using Snellen charts, color vision with Ishihara plates, field of vision via confrontation tests, and fundus examination. It also covers motor assessments for eye muscles and mastication, pupillary light and accommodation reflexes, and corneal reflex testing. Clear guidance is provided on identifying abnormalities and differentiating nerve palsies, making it an essential resource for pediatric neurological assessment.

Takeaways

• 😀 Olfactory nerve (CN I) assesses the sense of smell, only reliably testable in children over five years old using familiar, non-irritating substances.
• 😀 Visual function (CN II) is tested through far and near visual acuity, color vision, visual field testing, and fundus examination using tools like Snellen chart, Ishihara chart, confrontation test, and ophthalmoscope.
• 😀 Visual acuity is recorded as a fraction of distance the child can read versus the distance a normal person can read; near vision is tested at 30–35 cm.
• 😀 Extraocular movements assess CN III, IV, and VI; abnormal eye positions or double vision indicate possible cranial nerve palsy.
• 😀 Pupillary light reflex tests involve both direct (same eye) and indirect (contralateral eye) responses, with CN II as afferent and CN III as efferent limb.
• 😀 Accommodation reflex involves convergence of the eyes, lens adjustment, and pupillary constriction when focusing on a near object.
• 😀 Light-near dissociation may occur when the accommodation reflex is preserved but the pupillary light reflex is impaired, seen in conditions like Argyll Robertson pupil.
• 😀 Trigeminal nerve (CN V) has sensory and motor components; sensory function is tested with touch, pain, and temperature across ophthalmic, maxillary, and mandibular branches.
• 😀 Motor function of CN V involves muscles of mastication; jaw deviation toward the affected side indicates trigeminal nerve palsy.
• 😀 Corneal reflex testing evaluates the afferent limb via CN V and efferent limb via CN VII, with normal response producing bilateral blinking.
• 😀 Proper explanation and age-appropriate modifications are critical for pediatric cranial nerve examination to ensure accurate assessment and cooperation.

Q & A

At what age can the olfactory nerve (Cranial Nerve I) function be reliably tested in children?

The olfactory nerve function can be reliably tested in children older than five years.

What substances should be used when testing the sense of smell, and which should be avoided?

Known non-irritating substances, like chocolate or hing, should be used. Irritating substances should be avoided because they can stimulate the trigeminal nerve.

How is visual acuity measured using the Snellen chart?

Visual acuity is measured using the formula d/D, where 'd' is the distance between the child and the chart (usually 6 meters), and 'D' is the distance at which a normal person can read the smallest line the child can read.

What is the normal visual acuity at birth and by six years of age?

Normal visual acuity at birth is 6/45 and improves to 6/6 by six years of age.

Which cranial nerves control eye movements, and how can their palsy be differentiated?

The third (oculomotor), fourth (trochlear), and sixth (abducent) cranial nerves control eye movements. Palsy can be differentiated by the position of the eye: CN III palsy causes outward and downward displacement, CN IV causes upward and outward displacement, and CN VI causes inward displacement.

How is the pupillary light reflex tested and what do direct and indirect reflexes indicate?

A light is shone into one eye to test the pupillary light reflex. Constriction of the stimulated eye is the direct reflex, while constriction of the opposite eye is the indirect reflex. Absence of these reflexes can indicate optic nerve (CN II) or oculomotor nerve (CN III) damage.

What is the accommodation reflex and what are its components?

The accommodation reflex occurs when the eyes shift focus from a distant to a near object. It involves convergence of both eyes, contraction of the ciliary muscles, and pupillary constriction.

Which branches of the trigeminal nerve (Cranial Nerve V) supply sensation to the face?

The ophthalmic, maxillary, and mandibular branches supply sensation to the face, except for the angle of the jaw, which is supplied by C2 and C3.

How is motor function of the trigeminal nerve tested?

Motor function is tested by examining the muscles of mastication (masseter, temporalis, and pterygoid). The child is asked to clench teeth, move the jaw in various directions, and muscle contraction is palpated and tested against resistance. Jaw deviation toward the affected side indicates CN V palsy.

What is the corneal reflex and which cranial nerves are involved?

The corneal reflex is a blinking response when the cornea is touched. The afferent limb is the ophthalmic branch of CN V, and the efferent limb is CN VII.

What are common causes of anosmia in children?

Anosmia can be caused by upper respiratory tract infections, allergic disorders, nasal masses, or trauma.

What is light-near dissociation and in which conditions can it occur?

Light-near dissociation is when the pupillary light reflex is impaired but the accommodation reflex remains intact. It can occur in conditions such as neurosyphilis (Argyll Robertson pupil), dorsal midbrain syndrome, or diabetes mellitus (Eddies pupil).