Which cranial nerve is associated with tic douloureux

▪ THE CLINICAL SYNDROME

Trigeminal neuralgia is a severe, almost exclusively unilateral, neuropathic pain located within the distribution of the trigeminal nerve, manifesting as paroxysmal high-intensity stabbing pain lasting seconds. Each attack may be followed by a refractory period, a period of relief that lasts seconds, minutes, or even hours. The burst of pain can occur spontaneously and/or can be triggered by stimulating a specific area of the face known as a trigger zone. Trigger zones can be difficult to locate; they exist anywhere within the trigeminal distribution, including intraorally. The trigger zone is located in the same division of the trigeminal nerve as the pain. For this reason, patients characteristically avoid touching the face, washing, shaving, biting or chewing, or any other maneuver that stimulates the trigger zones and produces the pain.4 This avoidance is an invaluable clue to the diagnosis. With almost every other facial pain syndrome, patients massage, abrade, or apply heat and cold to the painful area; however, in trigeminal neuralgia, exactly the opposite occurs: patients avoid any stimulation of the face or mouth. The pain is often characterized as an “electric shock” and is typically accompanied by a unilateral grimace, hence the designation tic douloureux. The pain may occur daily for weeks or months and then cease, sometimes for years, before returning; these are known as periods of remission.

Although clinically described for centuries, the etiology of trigeminal neuralgia and the other cranial neuralgias is not fully understood. The integrity of the myelin sheath has been the focal point of investigation for years; however, the only agreement is that there is a dysfunction of the trigeminal sensory system.5 Trigeminal neuralgia is classified as primary (idiopathic or type 1), or secondary (type 2), which is due to compression or irritation, tumor, or disease, such as multiple sclerosis.

Intermittent trigeminal neuralgia is uncommon in multiple sclerosis, with an incidence between 1% and 2%.6,7 Conversely, the incidence of multiple sclerosis among patients with trigeminal neuralgia is approximately 3%. Patients with multiple sclerosis and trigeminal neuralgia typically have a classic trigeminal neuralgia history, except that the trigeminal neuralgia appears at a younger age when patients have multiple sclerosis than when the disease occurs in its idiopathic form. Some patients with multiple sclerosis manifest recurrent episodes of face pain that are generally long-lasting, not stabbing or lancinating, and without associated trigger zones. These patients are assumed to not have true trigeminal neuralgia, but a form of atypical facial pain.

Trigeminal neuralgia can occur as the first manifestation of multiple sclerosis, but this is rare. Most patients who have trigeminal neuralgia in association with multiple sclerosis have significant physical signs of multiple sclerosis for many years before the facial pain begins. Most, for example, have paraparesis or paraplegia, which are disorders of sensory function. Bilateral trigeminal neuralgia occurs more often than expected in patients with multiple sclerosis.

On rare occasions, trigeminal neuralgia may be a manifestation of brain stem disease and has been reported to result from pontine infarction.8 Neoplasms involving the trigeminal nerve generally produce constant neuropathic pain associated with sensory loss. Animal models have not been able to reproduce the pain of trigeminal neuralgia, and this limits our ability to study the condition on a basic science level.

Trigeminal Neuralgia

Trigeminal neuralgia affects approximately 4 in 100,000 individuals and is characterized by brief episodes of severe, lancinating pain in one or more of the three divisions of the trigeminal nerve, usually V2 and V3. Patients often describe that it is precipitated by touch or extremes of temperature. In extreme cases, a patient may refuse to eat or shave to avoid triggering the severe jolts of pain. Sensation usually remains intact, and significant numbness or jaw weakness leads to suspicion of a compressive mass lesion, such as tumor. Often, patients are referred with an already established diagnosis. It is reassuring if the patient has responded at some point to medication. MRI is used to rule out posterior fossa tumors and multiple sclerosis, which can present with related symptoms. Most patients respond to the oral administration of carbamazepine. Baclofen and gabapentin also have some clinical usefulness in medical treatment. The most common mechanism is presumed to be related to vascular compression of the fifth cranial nerve as it enters the brainstem (Fig. 68.22). With aging, the arteries elongate and can then begin to loop against the cranial nerves. At its entry to the pons, the fifth nerve has lost its peripheral nerve supportive architecture, the reticulin and mesenchymal elements that toughen the nerve more peripherally. Focal pulsatile pressure of the artery against this vulnerable part of the nerve results in ephaptic transmission from large myelinated fibers to small myelinated (A delta) and unmyelinated fibers.

Surgical therapy is usually reserved for patients who fail to respond to medical treatment. Microvascular decompression involves a small suboccipital craniotomy for microsurgical exploration of the dorsal root entry zone of the trigeminal nerve on the affected side. The offending vessel, usually the superior cerebellar artery, is then dissected off the nerve, and a barrier (Teflon or polyvinyl alcohol sponge) is placed between the vessel and nerve to prevent continued pulsatile focal compression. In especially favorable situations, the offending artery can be dissected free to loop away from the nerve, without the need for padding. A small sling of arterial patch graft material can also be sewn to hold the artery loop away from the nerve.

Percutaneous trigeminal rhizotomy techniques generally involve radiofrequency heat lesioning of the trigeminal ganglion, glycerol injection (Fig. 68.23) into the spinal fluid of Meckel cave (which causes an osmotic damage preferentially to the smaller pain-carrying nerve fibers), or mechanical trauma to the nerve or ganglion by transient inflation of a No. 4 Fogarty catheter balloon. Each method has its proponents along with advantages and disadvantages.

SRS has been described for the treatment of trigeminal neuralgia.46 Initial results have been encouraging, and ongoing evaluation of specific indications and long-term follow-up are ongoing.

Clinical Features

Tic douloureux is diagnosed almost exclusively on the basis of the patient’s history (Box 48.1). The International Headache Society defined trigeminal neuralgia as a “sudden, usually unilateral, severe, brief, stabbing, and recurrent pain in the distribution of one or more branches of the fifth cranial nerve.”17,18 The three divisions of the trigeminal nerve are the ophthalmic, maxillary, and mandibular. For the accurate diagnosis of facial pain, a detailed knowledge of the anatomy of the fifth cranial nerve is essential. By definition, the pain of tic douloureux is confined to the distribution of one trigeminal nerve (Fig. 48.1) and more commonly affects the lower part of the face than the upper.16 The maxillary division of the fifth cranial nerve (V2) is the site of pain alone or in combination with other divisions, most commonly the mandibular division (V3) in 45% of cases. The ophthalmic division (Vl) is least likely to be affected in trigeminal neuralgia (Fig. 48.2). A small number of patients have similar pain syndromes in the territories of the nervus intermedius, glossopharyngeal nerve, or vagus nerve. The pain of untreated tic douloureux occurs unpredictably and is sudden in onset, severe in degree, and short in duration. Often the patient can experience many paroxysms of pain within a single hour, and such bouts may go on for days, with some fluctuation in frequency from hour to hour and day to day. Early in the course of the syndrome, pain-free periods lasting months are common, but as time goes on these natural remissions tend to become less frequent and less prolonged. Although tic pain is ordinarily spontaneous in onset, it can frequently be triggered by a non-noxious stimulus, such as touching the skin on that side of the face, chewing, swallowing, or talking. Some patients are sensitive in certain areas of the face, called trigger zones, which when touched cause an attack of pain. Even a gentle breeze can trigger pain in some patients. The pain has been described as lancinating, lightning-like, or electrical in quality, and has been likened to the pain experienced when a dentist drills into the pulp of a tooth.7 The patient may wince in response to the pain, hence the name tic douloureux. A history of bilateral tic pain can be elicited in 3% of patients, although no patient has bilateral tic pain during one episode.16

Often the patient who develops tic douloureux sees the dentist first, because lancinating lower facial pain seems to be arising from a certain tooth or teeth. Dentists are often fixated on peripheral lesions as the cause for pain. A diseased tooth in the upper jaw can cause headache on the same side, which may radiate into the orbit or face. A diseased tooth in the lower jaw may cause considerable pain in the distribution of the mandibular division of the nerve, including pain deep in the ear. In addition, dental pain is much more common than tic douloureux. Teeth may be extracted or other dental procedures performed without providing any relief of the pain of tic douloureux. The patient may also consult more than one physician before the correct diagnosis is made. In the majority of patients, the trigeminal neuralgia is idiopathic in that there is no identifiable cause.8 However, the presence of sensory loss mandates a thorough search for structural pathology. Patients with idiopathic trigeminal neuralgia can develop more atypical features with time in the absence of efficacious therapy. In all likelihood, this development coincides with ongoing neuropathic injury. Pain that is continuous, lacks a shock-like quality, or is associated with objective evidence of cranial nerve dysfunction should raise the suspicion of diseases other than idiopathic trigeminal neuralgia. However, the most likely cause of this type of pain is a prior ablative procedure that damages the trigeminal nerve. Atypical facial pain is described as deep, burning, and continual. There is no jabbing onset as occurs in tic douloureux. The pain can radiate behind the ear, down onto the neck, or across to the opposite maxillary area. These patients, in contrast, often clutch their face, unlike the patient with tic douloureux who shields her face but is very careful not to actually touch it (Table 48.1). Myofascial pains involving the muscles of mastication and temporomandibular joint pain occur predominantly in the lateral face. They are also described as aching, burning, or cramping pains, and are often associated with tenderness to palpation of the involved muscles.16

Deviations from the typical picture of tic douloureux can occur, although the more unusual features the patient manifests, the less likely is a favorable response to either medical or surgical therapies. Furthermore, surgical procedures that damage the trigeminal nerve can produce changes in the findings and in the patient’s symptoms. Nerve damage can lead to a burning component of the pain, although these iatrogenically acquired changes in the pain syndrome do not alter the original diagnosis. It is therefore essential to ascertain what the symptoms were prior to any intervention.

Abstract

Trigeminal neuralgia is one of the most severe forms of pain in the human experience. It is a chronic neuropathic disease characterized by recurrent attacks of lancinating facial pain occurring in the dermatomal distribution of the fifth cranial nerve. In most cases, the disorder affects only one side of the face. Trigeminal neuralgia is usually caused by compression from an intracranial artery (classical type). The secondary forms can be provoked by a neurological disease. There is no diagnostic test for a definite diagnosis of trigeminal neuralgia. Although the diagnosis is essentially clinical, neuroimaging plays a paramount role in knowing the etiology (secondary forms) and for identifying the surgical indications for decompression. Pharmacotherapy remains the first line of treatment. If acute pain persists despite drug therapy, surgical microvascular decompression or neuroablative treatments can be considered. Despite therapy, this disease continues to challenge health care providers due to its impact on patient's psychological states. Patients must be enrolled in programs that can provide multi-professional support. This chapter aims to address multiple aspects of the disease including the extend of the problem, etiology, mechanisms, clinical features, and diagnosis. Furthermore, it reviews the current treatments and their implications for the patient's prognosis.

8 Describe the natural history of trigeminal neuralgia

In idiopathic trigeminal neuralgia, onset is most likely after the age of 50. Patients below the age of 40 with true or symptomatic trigeminal neuralgia should be investigated for an underlying demyelinating lesion. Other structural pathology may include an underlying tumor (e.g., meningioma, ependymoma). Similarly, if there is bilateral involvement, suspect multiple sclerosis.

The disease usually follows an exacerbating but remitting course. Over 50% of individuals will have at least a 6-month remission during their lifetime. There may be months or years when the patient is pain free. Therefore, drug holidays should be attempted to see if the patient is indeed responding to the drug or simply having a remission of the disease. In some patients, the attacks become more frequent and may be nearly continuous.

What are the 3 trigeminal nerves?

What is the main cause of trigeminal neuralgia?

What is the trigeminal nerve also known as?

Why is trigeminal neuralgia called tic douloureux?