Cranial Nerve Palsy and the Sixth Cranial Nerve Palsy

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  • Topic: Cranial nerves, Accessory nerve, Glossopharyngeal nerve
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Cranial Nerve Palsy: with an Emphasis on
Sixth Cranial Nerve Palsy

Cranial Nerve Palsy
With an Emphasis on
Sixth Cranial Nerve Palsy

I. What are Cranial Nerves?
* Cranial nerves are nerves that come directly from the brain stem in contrast to spinal nerves which come from segments of the spinal cord. * There are twelve Cranial nerves in humans that fit this description. * They mainly serve the motor and sensory systems of the head and neck region; except for the tenth and the eleventh nerve. * These nerves are divided to provide one or a few specific functions, and all of them can develop problems.

II. Cranial Nerves and Functions
* Olfactory Nerve: Smell
* Optic Nerve: Vision
* Oculomotor Nerve: Eye Movement; Pupil Dilation
* Trochlear Nerve: Eye Movement
* Trigeminal Nerve: Somatosensory information (touch, pain) from the face and head; muscles for chewing * Abducens Nerve: Eye Movement
* Facial Nerve: Taste
* Vestibulocochlear Nerve: Taste
* Glossopharyngeal Nerve: Taste
* Vagus Nerve: Sensory, Motor and Autonomic Functions of Viscera (glands, digestion, heart rate, etc.) * Spinal Accessory Nerve: Controls muscles used in head movement * Hypoglossal Nerve: Controls muscles of the tongue

III. Cranial Nerve Malfunctions
* Nerve 1 (Olfactory Nerve:  Anosmia (loss of smell)
* Nerve 2 (Optic nerve):  Anopsia (loss of vision)
* Nerve 3 (Oculomotor):  Strabismus, diplopia or double vision, ptosis, pupil enlargement and loss of focus * Nerve 4 (Trochlear):  Double vision and strabismus (head leans to injured side) * Nerve 5 (Trigeminal):  Trigeminal neuralgia

* Nerve 6 (Abducens):  Cannot turn eye laterally (abduct) * Nerve 7 (Facial):  Bell's palsy, loss of taste, inability to close eyelid * Cranial Nerve Malfunctions (con.)
* Nerve 8 (Vestibulocochlear):  Vertigo, nystagmus, tinnitus, hearing, balance * Nerve 9 (Glossopharyngeal):  Difficulty/pain in swallowing, lack of saliva, loss of feel in swallowing, loss of taste * Nerve 10 (Vagus):  Difficult in swallowing, numbness of oral pharynx, loss of internal organ biofeedback signal, effects parasympathetic input to the heart, lungs and gastro intestinal tract to the level of the splenic flexure of the colon * Nerve 11 (Accessory):  (innervates trapezius) Difficulty moving the head and/or raising shoulders * Nerve 12(Hypoglossal):  Difficult in speaking, swallowing, chewing, tongue degeneration

IV. Sixth Cranial Nerve Palsy: Etiology (Causes and Effects) Sixth cranial nerve palsy affects the lateral rectus muscle of the eye, causing reduced or no eye abduction. The eye may be slightly turned to the left or right when the person looks straight ahead, and the palsy may be linked to Wernicke's encephalopathy, diabetes mellitus, extremely high intercranial pressure, and small vessel disease of the brain and heart. Other causes of sixth cranial nerve palsy include head trauma, meningitis, aneurysm, multiple sclerosis, post-lumbar puncture and pontine stroke.

V. Sixth Cranial Nerve Palsy: Signs and Symptoms
* Diplopia (double vision) in either eye.
* The eye not being able to move past the midline
* Severe head pain (caused by stroke, tumor, or head trauma) * Paralysis of the sixth cranial nerve
* Loss of vision with optic nerve compression
* Sensitivity to light
* Sixth Cranial Nerve Palsy:
Diagnosis and Treatment
* A sixth cranial nerve palsy is usually obvious from the way a person’s eyes look, but the cause is not. * A doctor would have to run several tests to determine the cause for the palsy, and some of them are time consuming.

VI. Tests and treatments for sixth cranial nerve palsy include: * CT (with contrast)
* MRI (with contrast)
* Visual Field Acuity
* Blood work
* Prism lens for glasses
* Surgery

VII. Sixth Cranial Nerve Palsy:...
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