Cranial Nerve Disorders

95 Cranial Nerve Disorders






Epidemiology


Cranial neuropathies are a heterogeneous group of disorders with a variety of causes. Trauma is a common cause, and diabetes and hypertension are common comorbid conditions. Cranial nerves I, VI, and VII are the most frequently affected after minor head trauma.1 Trigeminal neuralgia is a common cause of facial pain that affects approximately 4.5 per 100,000 individuals; women are affected twice as often as men, and it is more common in those older than 60 years.2 Trigeminal neuralgia can be severely debilitating and has been termed the “suicide disease.”3 Bell palsy is the most common cause of acute facial paralysis worldwide. The peak age at incidence has been reported to be between 15 and 45 years,4 but other investigators have noted an increased incidence in individuals older than 70.5,6 Pregnant women and patients with diabetes have an associated increased incidence of the disease. A familial association of Bell palsy is noted in 4% of cases,4 and it can cause both significant psychologic and physical morbidity.



Pathophysiology




Cranial Nerve II (Optic Nerve)







Cranial Nerve III (Oculomotor Nerve)




Presenting Signs and Symptoms


The patient typically complains of double vision or difficulty seeing out of the affected eye. There may be mild photophobia in bright light. The patient may also complain of an inability to raise the eyelid (ptosis).


Cranial nerve III palsy is more common in patients older than 60 years and in those with diabetes or hypertension (Fig. 95.1).



Patients with herniation syndromes will have a history of trauma (Fig. 95.2), tumor, or other neurologic findings.7



Pain associated with unilateral mydriasis should alert the emergency physician (EP) to look for an aneurysm involving the terminal internal carotid artery. Computed tomographic angiography is more reliable than magnetic resonance angiography.8


Patients with an abscess or cavernous sinus thrombosis may have headaches, altered mental status, and seizures. This diagnosis should be considered in patients with signs and symptoms in the contralateral eye, previous sinus or midface infection, fever, chemosis, eyelid or periorbital edema, and exophthalmos. Extension of internal carotid artery dissection intracranially into the cavernous sinus can result in third, fourth, and sixth cranial nerve palsies.9





Cranial Nerve V (Trigeminal Nerve)




Presenting Signs and Symptoms


Patients with trigeminal nerve dysfunction have either sensory or motor deficits. Sensory dysfunctions include paroxysmal pain, paresthesias (abnormal sensations such as burning, pricking, tickling, or tingling), dysesthesias (disagreeable, unpleasant, or painful sensations produced by ordinary stimuli), and anesthesia (loss of sensation). The motor dysfunction is usually described as difficulty chewing and difficulty swallowing.


Peripheral lesions cause loss of sensation or pain in only one division. Positive findings in two or more divisions (e.g., loss of light touch in one division and loss of sensitivity to pain, temperature, or pinprick in another division) should raise suspicion for a central cause.


The presence of associated cranial nerve deficits (III, IV, IV, or any combination of these nerves) suggests cavernous sinus involvement. In the setting of trauma, if a bruit over the orbit can be detected, a carotid–cavernous sinus fistula may be present. Associated involvement of cranial nerve VII or VIII or gait ataxia should raise suspicion for a cerebellopontine angle or lateral pontine tumor (Table 95.1).



Associated Horner syndrome may indicate a cervical or lateral brainstem lesion.


The main categories of trigeminal nerve dysfunction are trigeminal neuralgia and trigeminal neuropathy. A sudden onset of symptoms should raise suspicion for a vascular, traumatic, or demyelinating cause, whereas a more indolent course suggests tumor or inflammation (Table 95.2).


Table 95.2 Selected Specific Causes Associated with Trigeminal Nerve Disorders












































































ETIOLOGIC CATEGORY SELECTED SPECIFIC CAUSES
Structural Disorders
Developmental Brainstem vascular loop, syringobulbia
Degenerative and compressive Paget disease
Hereditary and Degenerative Disorders
Chromosomal abnormalities, neurocutaneous disorders Hereditary sensorimotor neuropathy type I, neurofibromatosis (schwannoma)
Degenerative motor, sensory, and autonomic disorders Amyotrophic lateral sclerosis
Acquired Metabolic and Nutritional Disorders
Endogenous metabolic disorders Diabetes
Exogenous disorders (toxins, illicit drugs) Trichloroethylene, trichloroacetic acid
Nutritional deficiencies, syndromes associated with alcoholism Thiamine, folate, vitamin B12, pyridoxine, pantothenic acid, vitamin A deficiencies
Infectious Disorders
Viral infections Herpes zoster, unknown
Nonviral infections Bacteria, tuberculous meningitis, brain abscess, Gradenigo syndrome, leprosy, cavernous sinus thrombosis
HIV infection, AIDS Opportunistic infection; abscess, herpes zosterStroke, hemorrhage, aneurysm
Neurovascular Disorders
Neoplastic Disorders
Primary neurologic tumors Glial tumors, meningioma, schwannoma
Metastatic neoplasms, paraneoplastic syndromes Lung, breast; lymphoma, carcinomatous meningitis
Demyelinating Disorders
Central nervous system disorders Multiple sclerosis, acute demyelinating encephalomyelitis
Peripheral nervous system disorders Guillain-Barré syndrome, chronic inflammatory demyelinating polyneuropathyTolosa-Hunt syndrome, sarcoidosis, lupus, orbital pseudotumor
Autoimmune and Inflammatory Disorders
Traumatic Disorders Carotid-cavernous fistula, cavernous sinus thrombosis, maxillary/mandibular injury
Epilepsy Focal seizures
Headache and Facial Pain Raeder neuralgia, cluster headache
Drug-Induced and Iatrogenic Neurologic Disorders Orbital, facial, dental surgery

AIDS, Acquired immunodeficiency syndrome; HIV, human immunodeficiency virus.


From Goetz CG, editor. Textbook of clinical neurology. 2nd ed. Philadelphia: Saunders; 2003.



Jun 14, 2016 | Posted by in EMERGENCY MEDICINE | Comments Off on Cranial Nerve Disorders

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