Researchers examined the risk of tinnitus within 1 year following trigeminal neuralgia using data from the Taiwan National Health Insurance Research Dataset, and a retrospective cohort study design.
Tinnitus is the auditory phantom sensation of sound in the absence of external stimuli. About 10% of the population suffers from tinnitus, making it one of the most common health conditions in the world [1, 2]. The most common cause of tinnitus is tinnitus associated with hearing loss caused by noise overexposure and aging. However, tinnitus can result from non-otologic causes, such as head and neck trauma , temporomandibular disorders [4,5,6,7], and cervical spine disorders [8, 9]. A certain percentage of patients find their tinnitus provoked by the movement of or applying pressure to the head and neck region [10, 11]. Research has shown that the somatic origins of tinnitus may be due to interactions between somatic and auditory neuronal pathways in the central nervous system, indicating the role of somatosensory components in some cases of tinnitus [10, 12,13,14,15,16].
Trigeminal neuralgia is a common cause of chronic orofacial pain due to inflammation or other pathology of the trigeminal nerve. The trigeminal nerve, which divides into three branches, the ophthalmic (V1), maxillary (V2), and mandibular (V3) branches, is responsible for the sensory supply of the orofacial region. Trigeminal neuralgia is characterized by extremely disturbing, sporadic, and recurrent episodes of burning facial pain. While it is typically characterized by paroxysmal attacks of facial pain, atypical trigeminal neuralgia may manifest as a less intense condition associated with a constant background pain without intervals of relief.
Trigeminal neuralgia, like other pain disorders of the head and neck region such as temporomandibular disorders (TMD) and cervical spine disorders (CSD), is thought to be associated with the transmission of nociceptive inputs through the trigeminal nerve which converges with other somatosensory pathways in the brainstem [17,18,19]. There is increasing evidence of tinnitus originating from hyperactivity across neuronal ensembles along the auditory pathway [20,21,22], and from functional and anatomical interchanges between the somatosensory and auditory pathways in the brainstem [14, 23,24,25]. Previous animal studies have demonstrated that the trigeminal nerve input interacts with the neural activity of the central auditory pathways related to sound perception at the level of the dorsal cochlear nucleus [13, 26]. This may explain the mechanism of tinnitus experienced by some patients with trigeminal nerve pathology. Pathophysiologic involvement of the trigeminal system in tinnitus is also supported by clinical observations that tinnitus sensation can be elicited or is reported to be triggered by certain face and jaw movements in some patients [10, 11, 27].
Therefore, it is reasonable to hypothesize a prospective or comorbid association between trigeminal neuralgia and tinnitus. To the best of our knowledge, there is no documented study that explored tinnitus risk following a diagnosis of trigeminal neuralgia. This nationwide, population-based, retrospective cohort study was carried out to investigate the risk of tinnitus within 1 year following a diagnosis of trigeminal neuralgia.
The dataset provided data from 12,587 patients diagnosed with trigeminal neuralgia from January 2001 to December 2014. From the remaining patients, 12,587 comparison patients without trigeminal neuralgia were identified by propensity score matching, using gender, age, monthly income, geographic region, residential urbanization level, and tinnitus-relevant comorbidities (hyperlipidemia, diabetes, coronary heart disease, hypertension, cervical spondylosis, temporomandibular joint disorders and injury to head and neck and index year). The incidence of tinnitus was 18.21 per 100 person-years among the total 25,174 sample patients.
Patients with trigeminal neuralgia exhibited a rate of 23.57 vs 13.17 among comparison patients. Findings indicate a significantly raised risk of tinnitus within 1 year of trigeminal neuralgia diagnosis vs those without the diagnosis.