Trigeminal Neuralgia (Tic Douloureux) Painful neuralgia of the trigeminal nerve results in the clinical syndrome of tic douloureux or trigeminal neuralgia. The paroxysmal disorder presents as excruciating, lancinating painful spasms affecting one or more divisions of CN V. Trigeminal neuralgia is unilateral and usually affects the second or third division of CN V (3rd>2nd>1st). In less than 5 percent of cases V1 is affected, whereas V3 is affected in more than 70 percent of cases.Rarely, pain may occur bilaterally, although simultaneous bilateral spasms are quite atypical. The pain occurs spontaneously as brief lightning-like spasms lasting seconds to minutes, or pain may be precipitated by cutaneous or auditory stimuli. In many instances, there is a demonstrable trigger point that can reproduce pain, and some patients may be unable to chew, eat, drink, shave, or brush their teeth for fear of triggering a spasm. Paroxysms recur throughout the day and night. Between attacks, there are no symptoms, but the patient is usually anxious about having another attack. Objective sensory or motor deficits are not a feature, although a subjective report of hypesthesias over the face may be reported. Often there is a temporal summation of stimuli necessary to invoke a response. The pain is reported as lancinating, stabbing, searing, burning, or electrical, and the intensity is such that the patient often winces or grimaces in a tic-like fashion. Trigeminal neuralgia affects approximately 155 people per million population and has a slight female predominance (3:2). It is the most common neuralgia, and its incidence peaks in middle age. The age of onset is important, however, because the appearance of trigeminal neuralgia in a young patient should raise the suspicion of demyelinating disease such as multiple sclerosis or another structural brain stem disorder. Pathological analyses of trigeminal biopsy specimens taken during vascular decompression have described focal demyelination but no inflammatory cells/ Abnormal ephaptic nonsynaptic neurotransmission between demyelinated trigeminal axons within the nerve root, ganglion, or spinal trigeminal nucleus may provide the physiological substrate for the paroxysmal pain characteristic of trigeminal neuralgia, especially if initiated by cutaneous stimuli. On physical examination, objective neurological deficits are not present. The patient, however, may appear emaciated if, for example, a trigger point is initiated during chewing, or males may appear disheveled if shaving induces a spasm. Laboratory study results are normal. Careful inspection and palpation of the teeth, gums, nares, nasal sinuses, palate, and pharynx should be performed because disease processes such as infections or inflammatory disorders in these regions can cause significant facial pain. MRI of patients with trigeminal neuralgia may be helpful in identifying other etiologies or associated disorders. The diagnosis of tic douloureux can usually be made by history alone, but the disorder must be distinguished from other causes of facial pain syndromes such as glossopharyngeal neuralgia, which can be confused with tic douloureux that involves the third division of CNV. Herpes zoster or post-herpetic neuralgia may also provide some diagnostic confusion. Tumors or vascular lesions of the cerebellopontine angle or within the trigeminal ganglion itself may induce pain similar to that of trigeminal neuralgia, although these disorders can be distinguished by findings of trigeminal sensory loss, atrophy of facial masticatory muscles, diminished corneal reflexes, and involvement of other adjacent brain stem structures that are not characteristic of trigeminal neuralgia. The nature of the pain in these cases is also distinct from that of trigeminal neuralgia in that it is often continuous and unremitting rather than episodic. Goetz: Textbook of Clinical Neurology, 1st ed., Copyright © 1999 W. B. Saunders Company TRIGEMINAL NEURALGIA (from Merck Manual) (Tic Douloureux) A disorder of the trigeminal nerve producing bouts of excruciating, lancinating pain, lasting between seconds and 2 min, along the distribution of one or more of its sensory divisions, most often the maxillary. At surgery or autopsy, intracranial arterial and, less often, venous loops compressing the trigeminal nerve root where it enters the brain stem have been found, suggesting that the tic is a compressive neuropathy. The disorder usually affects adults, especially the elderly. Pain is often set off by touching a trigger point or by activity (eg, chewing or brushing the teeth). Although each bout of intense pain is brief, successive bouts may be incapacitating. Diagnosis Usually, the history is typical and diagnostic. No clinical or pathologic signs accompany trigeminal neuralgia, so finding a sensory or cranial nerve abnormality requires search for a structural cause of the pain, such as a neoplasm, a multiple sclerosis plaque, or another lesion impinging on the nerve or its pathways in the brain stem. Pontine lesions usually result in sensory and motor dysfunction; a medullary lesion causes only sensory loss of pain and temperature with loss of the corneal reflex. Differential diagnosis includes neoplasm, vascular malformation of the brain stem, a vascular insult, and multiple sclerosis (especially in a younger patient). Postherpetic pain is differentiated by its typical antecedent rash, scarring, and predilection for the ophthalmic division. Trigeminal neuropathy may occur in Sjögren's syndrome or RA, but with a sensory deficit that is often perioral and nasal. Migraine may produce atypical facial pain, with normal examination results, but the pain is more prolonged and is burning or throbbing. Trigeminal Neuralgia (tic Douloureux) The most striking disorder of trigeminal nerve function is tic douloureux, a condition characterized by excruciating paroxysms of pain in the lips, gums, cheek, or chin and, very rarely, in the distribution of the ophthalmic division of the fifth nerve. The disorder occurs almost exclusively in middle-aged and elderly persons. The pain seldom lasts more than a few seconds or a minute or two but may be so intense that the patient winces, hence the term tic . The paroxysms recur frequently, both day and night, for several weeks at a time. Another characteristic feature is the initiation of pain by stimuli applied to certain areas on the face, lips, or tongue ("trigger zones") or by movement of these parts. Objective signs of sensory loss cannot be demonstrated . The adequate stimulus to a trigger zone for precipitating an attack is a tactile one and possibly tickle, rather than a noxious or thermal stimulus. Usually a spatial and temporal summation of impulses is necessary to trigger an attack, which is followed by a refractory period of up to 2 or 3 min. The diagnosis of this disorder rests on these strict clinical criteria, and the condition must be distinguished from other forms of facial and cephalic neuralgia and pain arising from diseases of the jaw, teeth, or sinuses (Chap. 15 ). Tic douloureux is usually without assignable cause; in typical cases, neuroimaging studies are not necessary. On occasion, when trigeminal neuralgia develops in a younger adult, it may be due to a plaque of multiple sclerosis at the root entry zone of the fifth nerve in the pons. Very rarely it occurs with herpes zoster or a tumor. To a degree that remains uncertain, pain of tic douloureux may be caused by a redundant or tortuous blood vessel in the posterior fossa, causing an irritative lesion of the nerve or its root. Usually, however, lesions such as aneurysms, neurofibromas, or meningiomas affecting the nerve produce a loss of sensation (trigeminal neuropathy, see below). Treatment Drug therapy with carbamazepine is the initial treatment of choice and is effective in approximately 50 to 75% of patients. Carbamazepine should be started as a single daily dose of 100 mg taken with food, and increased gradually (by 100 mg daily every 1 to 2 days) until substantial (>50%) pain relief is achieved. Most patients require a maintenance dose of 200 mg qid. Doses >1200 mg daily provide no additional benefit. Dizziness, imbalance, sedation, and rare cases of agranulocytosis are the most important side effects of carbamazepine. If treatment is effective, it is usually continued for approximately 1 month and then tapered as tolerated. If carbamazepine is not well tolerated or is ineffective, phenytoin, 300 to 400 mg daily, can be tried. Baclofen may also be administered, either alone or in combination with carbamazepine or phenytoin. The initial dose is 5 to 10 mg tid, gradually increasing as needed to 20 mg qid. If drug treatment fails, surgical therapy should be offered. The most widely applied procedure creates a heat lesion of the trigeminal (gasserian) ganglion or nerve, a method termed radiofrequency thermal rhizotomy . Injection of glycerol in Meckel's cave is a method preferred by some surgeons. Either procedure produces short-term relief in >95% of patients; however, long-term studies indicate that pain recurs in a substantial percentage of treated patients in some series. Complications and morbidity are infrequent in experienced hands. These procedures result in partial numbness of the face and carry a risk of corneal denervation with secondary keratitis when used for the rare instances of first-division trigeminal neuralgia. A third treatment, microvascular decompression, requires a suboccipital craniectomy, a major procedure requiring several days of hospitalization. It has an 80% efficacy rate, but the pain may recur, and, in a small number of cases, there is damage to the eighth or seventh nerve. Chapter 367: Common Disorders Of the Cranial Nerves (Harrison's Textbook) Trigeminal Neuropathy A variety of diseases in addition to tic douloureux may affect the trigeminal nerve (Table 367-1 ). Most present with sensory loss on the face or with weakness of the jaw muscles. Deviation of the jaw on opening indicates weakness of the pterygoids on the side to which the jaw deviates. Tumors of the middle cranial fossa (meningiomas), of the trigeminal nerve (schwannomas), or of the base of the skull (metastatic tumors) may cause a combination of motor and sensory signs. Lesions in the cavernous sinus can affect the first and second divisions of the trigeminal nerve, and lesions of the superior orbital fissure can affect the first (ophthalmic) division. The accompanying corneal anesthesia increases the risk of ulceration (neurokeratitis). Table 367-1: Trigeminal Nerve Disorders Nuclear (brainstem) lesions                                                   Peripheral nerve lesions   Multiple sclerosis                                                                   Nasopharyngeal carcinoma   Stroke                                                                                    Trauma   Syringobulbia                                                                        Guillain-Barré syndrome   Glioma                                                                                  Sjögren's syndrome   Lymphoma                                                                            Collagen-vascular diseases Preganglionic lesions                                                              Sarcoidosis   Acoustic neuroma                                                                 Leprosy   Meningioma                                                                        Drugs (stilbamidine, trichloroethylene)   Metastasis                                                                           Idiopathic trigeminal neuropathy   Chronic meningitis   Cavernous carotid aneurysm Gasserian ganglion lesions   Trigeminal neuroma   Herpes zoster   Infection (spread from otitis media or mastoiditis) Loss of sensation over the chin (mental neuropathy) can be the only manifestation of systemic malignancy. Rarely, an idiopathic form of trigeminal neuropathy is observed. It is characterized by feelings of numbness and paresthesias, sometimes bilaterally, with loss of sensation in the territory of the trigeminal nerve but without weakness of the jaw. Recovery is the rule, but the symptoms may be troublesome for many months, or even years. Leprosy may involve the trigeminal nerves.