A 26-year-old woman comes to the office due to several weeks of pain and muffled hearing in the left ear, along with a sensation of jaw clicking when chewing food. The patient has had episodic headaches and left-sided facial pain for several years that is worse when moving her jaw. She also has been told that she grinds her teeth while asleep. On examination, the patient is unable to fully open her mouth and reports pain with passive movement of the jaw. The external auditory canal and tympanic membrane are normal. A disorder affecting pterygoid muscle contractility is suspected. Involvement of which of the following nerves is most likely contributing to this patient's ear symptoms?

Question

A 26-year-old woman comes to the office due to several weeks of pain and muffled hearing in the left ear, along with a sensation of jaw clicking when chewing food.  The patient has had episodic headaches and left-sided facial pain for several years that is worse when moving her jaw.  She also has been told that she grinds her teeth while asleep.  On examination, the patient is unable to fully open her mouth and reports pain with passive movement of the jaw.  The external auditory canal and tympanic membrane are normal.  A disorder affecting pterygoid muscle contractility is suspected.  Involvement of which of the following nerves is most likely contributing to this patient's ear symptoms?

Quizplus · Accepted Answer

This patient's facial pain, headaches, jaw dysfunction, and ear pain/muffled hearing are characteristic of temporomandibular disorder (TMD). The underlying etiology of TMD is multifactorial but includes temporomandibular joint (TMJ) derangement (eg, jaw misalignment, trauma) and hypersensitivity of the mandibular nerve. The mandibular nerve (CN V3) is the largest branch of the trigeminal nerve and supplies sensation to the TMJ, floor of the mouth, anterior tongue, and the lower part of the face. It also innervates the muscles of mastication (eg, medial and lateral pterygoid, masseter, temporalis), tensor veli palatini, and the tensor tympani in the middle ear, which dampens loud sounds by tensing the tympanic membrane. Mechanical derangement of the TMJ can result in irritation and hypersensitivity of the mandibular nerve, leading to pathologic contraction of the pterygoid muscles (worsening the jaw pain and dysfunction) and tensor tympani (causing ear pain and muffled hearing despite a normal otoscopic examination). (Choice A) Most patients with TMD have cervical spinal dysfunction and neck pain due to muscular and functional connections between the jaw and cervical regions. However, cervical spinal nerve damage is usually caused by overt structural lesions of the cervical spine (eg, cervical spondylosis, disc herniation) and would not result in ear pain or muffled hearing (but rather neck, shoulder, and arm pain/weakness). (Choice B) The facial nerve (CN VII) provides sensory innervation to the external auditory canal/concha and motor innervation to the muscles of facial expression and the stapedius muscle, which dampens high-amplitude sound wave transmission. However, the facial nerve does not innervate the pterygoid muscles or TMJ. (Choice D) The maxillary nerve (CN V2) provides sensory innervation to the cheek, nares, upper lip, and teeth. Involvement of the maxillary nerve in trigeminal neuralgia can cause facial pain; however, muffled hearing and pterygoid muscle dysfunction indicate mandibular nerve involvement. (Choice E) The vestibulocochlear nerve (CN VIII) carries auditory and balance information from the inner ear. Damage to the cochlear portion of CNVIII (eg, vestibular schwannoma) can result in hearing loss; however, it would not be associated with facial pain or pterygoid muscle dysfunction. Educational objective: Temporomandibular disorder is associated with dysfunction of the temporomandibular joint and hypersensitivity of the mandibular nerve (CN V3). This can result in pathologic contraction of the pterygoid muscles (eg, jaw pain/dysfunction) and the tensor tympani in the middle ear (eg, ear pain, muffled hearing). __________ References: Signs and symptoms of temporomandibular joint disorders related to the degree of mouth opening and hearing loss. (http://www.ncbi.nlm.nih.gov/pubmed/21612586)

A 26-Year-Old Woman Comes to the Office Due to Several