In addition to the repeated episodes of paroxysmal, electrical facial pain classically associated with the disease, many patients with trigeminal neuralgia (TN) suffer from severe emotional distress. At present, there is no universally agreed pathophysiological explanation for the high incidence of depression and anxiety within this patient population. Despite the unclear understanding, the psychiatric comorbidities should be addressed as a part of comprehensive, multi-modal approach. Anticonvulsants or serotonin and norepineprhine reuptake inhibitors are viable pharmacological options that can supplement the currently used carbamazepine therapy. For medically refractory cases, surgical interventions are being suggested as effective alternatives in managing both the pain and the psychiatric complaints of TN. Examples include microvascular decompression, stereotactic radiosurgery, and repetitive transcranial magnetic stimulation. Continued research to understand TN should take into account the psychiatric burden in this population in order to promote a holistic treatment approach.
TopBackground
TN is one of the many pain conditions associated with the fifth cranial nerve. It is differentiated from trigeminal autonomic cephalgias, migraines, temporomandibular joint disorders, and post-herpetic neuralgia (Goadsby et al, Moskowitz et al, Karatas et al, Cook et al, Watson et al) (Watson, Evans, Watt, & Birkett, 1988) by clinical diagnostic criteria, which at least in part, seem to represent the specific pathogenesis of the pain. In TN, any one or more of the three branches of trigeminal nerve—V1 (ophthalmic nerve), V2 (maximally nerve), V3 (mandibular nerve)—may be involved. Historically, TN was also known as “tic douloureux,” which means painful tic in French (Cole, Liu, & Apfelbaum, 2005). This term captures the nature of pain associated with TN; the brief yet excruciating pain causes patients to grimace or make flinching facial expression that can be mistaken for tic disorders or Tourette syndrome. The initially poorly understood disease has been under the scrutiny of many researchers, and although we still have imperfect explanation for the underlying cause of the disease, we now have several treatment options, both medical and surgical, to relieve the pain.
The characteristic of facial pain experienced by TN patients can be described as sudden, intermittent, and stabbing kind of pain that is maximal at onset and often unilateral. Innocuous activities such as brushing teeth and chewing become triggers of extreme pain for patients with TN. Each episode is usually fairly brief, as short as few seconds and usually not longer than several minutes. But there may be hundreds of these episodes per day with variable pattern of remission, which can lead to severe limitation in daily function and significant impairment in quality of life (Zakrzewska & Linskey, 2016; Nurmikko & Eldridge, 2001).
Although not a part of diagnostic criteria, nonpainful symptoms can also be experienced in many TN patients. Approximately one-third of TN patients have symptoms like excessive tearing and rhinorrhea from dysregulation of autonomic system, such as those experienced by patients with trigeminal autonomic cephalgia. Abnormal sensory exam findings such as hypesthesia are equally common (Maarbjerg, Gozalov, Olesen, & Bendtsen, 2014).
Emotional disturbance is another clinical feature among TN patient population, which will be the focus of the rest of this chapter. Mood disorders like depression and anxiety disorders are some of the most common mental illness categories in the general population. The prevalence of these conditions is even higher in patients with patients with chronic pain (Tsang et al., 2008; McWilliams, Cox, & Enns, 2003).
Unipolar depression (to distinguish from bipolar disorder that has components of both depression and mania) is a clinical diagnosis made by the prolongation of depressed mood that leads to diminished interest, sense of guilt, hopelessness, sleep disturbances, psychomotor retardation, and even suicidal ideation (American Psychiatric Association, 2013). Also called major depressive disorder (MDD), depression may be secondary to preexisting illnesses, some of the classic causes being neurodegenerative conditions such as Huntington disease and Alzheimer disease (Reus et al., 2016).