Canadian Medical Guide > Diseases > Nervous System Diseases > Cranial Nerve Diseases Terms and Definitions




Cranial Nerve Diseases

Medical Definition: Disorders of one or more of the twelve cranial nerves. With the exception of the optic and olfactory nerves, this includes disorders of the brain stem nuclei from which the cranial nerves originate or terminate.
Guide Notes: GEN: prefer specifics
Also Called: Cranial Nerve Palsies,Cranial Neuropathies, Multiple
Previously Indexed: Cranial Nerves (1966-1980),Peripheral Nerve Diseases (1966-1980),specific cranial nerve (1966-1980)
Cranial Nerve Diseases Categories.
Canadian Medical Guide Definition Abducens Nerve Diseases - Diseases of the sixth cranial (abducens) nerve or its nucleus in the pons. The nerve may be injured along its course in the pons, intracranially as it travels along the base of the brain, in the cavernous sinus, or at the level of superior orbital fissure or orbit. Dysfunction of the nerve causes lateral rectus muscle weakness, resulting in horizontal diplopia that is maximal when the affected eye is abducted and ESOTROPIA. Common conditions associated with nerve injury include INTRACRANIAL HYPERTENSION; CRANIOCEREBRAL TRAUMA; ISCHEMIA; and INFRATENTORIAL NEOPLASMS.
Canadian Medical Guide Definition Accessory Nerve Diseases - Diseases of the eleventh cranial (spinal accessory) nerve. This nerve originates from motor neurons in the lower medulla (accessory portion of nerve) and upper spinal cord (spinal portion of nerve). The two components of the nerve join and exit the skull via the jugular foramen, innervating the sternocleidomastoid and trapezius muscles, which become weak or paralyzed if the nerve is injured. The nerve is commonly involved in MOTOR NEURON DISEASE, and may be injured by trauma to the posterior triangle of the neck.
Canadian Medical Guide Definition Cranial Nerve Injuries - Dysfunction of one or more cranial nerves causally related to a traumatic injury. Penetrating and nonpenetrating CRANIOCEREBRAL TRAUMA; NECK INJURIES; and trauma to the facial region are conditions associated with cranial nerve injuries.
Canadian Medical Guide Definition Facial Nerve Diseases - Diseases of the facial nerve or nuclei. Pontine disorders may affect the facial nuclei or nerve fascicle. The nerve may be involved intracranially, along its course through the petrous portion of the temporal bone, or along its extracranial course. Clinical manifestations include facial muscle weakness, loss of taste from the anterior tongue, hyperacusis, and decreased lacrimation.
Canadian Medical Guide Definition Glossopharyngeal Nerve Diseases - Diseases of the ninth cranial (glossopharyngeal) nerve or its nuclei in the medulla. The nerve may be injured by diseases affecting the lower brain stem, floor of the posterior fossa, jugular foramen, or the nerve's extracranial course. Clinical manifestations include loss of sensation from the pharynx, decreased salivation, and syncope. Glossopharyngeal neuralgia refers to a condition that features recurrent unilateral sharp pain in the tongue, angle of the jaw, external auditory meatus and throat that may be associated with SYNCOPE. Episodes may be triggered by cough, sneeze, swallowing, or pressure on the tragus of the ear. (Adams et al., Principles of Neurology, 6th ed, p1390)
Canadian Medical Guide Definition Hypoglossal Nerve Diseases - Diseases of the twelfth cranial (hypoglossal) nerve or nuclei. The nuclei and fascicles of the nerve are located in the medulla, and the nerve exits the skull via the hypoglossal foramen and innervates the muscles of the tongue. Lower brain stem diseases, including ischemia and MOTOR NEURON DISEASES may affect the nuclei or nerve fascicles. The nerve may also be injured by diseases of the posterior fossa or skull base. Clinical manifestations include unilateral weakness of tongue musculature and lingual dysarthria, with deviation of the tongue towards the side of weakness upon attempted protrusion.
Canadian Medical Guide Definition Olfactory Nerve Diseases - Diseases of the first cranial (olfactory) nerve, which usually feature anosmia or other alterations in the sense of smell and taste. Anosmia may be associated with NEOPLASMS; CENTRAL NERVOUS SYSTEM INFECTIONS; CRANIOCEREBRAL TRAUMA; inherited conditions; toxins; METABOLIC DISEASES; tobacco abuse; and other conditions. (Adams et al., Principles of Neurology, 6th ed, pp229-31)
Canadian Medical Guide Definition Optic Nerve Diseases - Conditions which produce injury or dysfunction of the second cranial or optic nerve, which is generally considered a component of the central nervous system. Damage to optic nerve fibers may occur at or near their origin in the retina, at the optic disk, or in the nerve, optic chiasm, optic tract, or lateral geniculate nuclei. Clinical manifestations may include decreased visual acuity and contrast sensitivity, impaired color vision, and an afferent pupillary defect.
Canadian Medical Guide Definition Trigeminal Nerve Diseases - Diseases of the trigeminal nerve or its nuclei, which are located in the pons and medulla. The nerve is composed of three divisions: ophthalmic, maxillary, and mandibular, which provide sensory innervation to structures of the face, sinuses, and portions of the cranial vault. The mandibular nerve also innervates muscles of mastication. Clinical features include loss of facial and intra-oral sensation and weakness of jaw closure. Common conditions affecting the nerve include brain stem ischemia, INFRATENTORIAL NEOPLASMS, and TRIGEMINAL NEURALGIA.
Canadian Medical Guide Definition Trochlear Nerve Diseases - Diseases of the fourth cranial (trochlear) nerve or its nucleus in the midbrain. The nerve crosses as it exits the midbrain dorsally and may be injured along its course through the intracranial space, cavernous sinus, superior orbital fissure, or orbit. Clinical manifestations include weakness of the superior oblique muscle which causes vertical DIPLOPIA that is maximal when the affected eye is adducted and directed inferiorly. Head tilt may be seen as a compensatory mechanism for diplopia and rotation of the visual axis. Common etiologies include CRANIOCEREBRAL TRAUMA and INFRATENTORIAL NEOPLASMS.
Canadian Medical Guide Definition Vagus Nerve Diseases - Diseases of the tenth cranial nerve, including brain stem lesions involving its nuclei (solitary, ambiguus, and dorsal motor), nerve fascicles, and intracranial and extracranial course. Clinical manifestations may include dysphagia, vocal cord weakness, and alterations of parasympathetic tone in the thorax and abdomen.

Cranial Nerve Diseases Medical Definitions and Terms

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