A 59-year-old woman comes to the office due to recurrent facial pain for the past month. The pain occurs only on the left side. It starts just in front of the ear as a shock-like sensation that quickly radiates down the jaw over 4-8 seconds, then resolves. It is most commonly triggered by chewing, so the patient sometimes skips meals to avoid the pain. Vital signs are normal. The patient has lost 4.5 kg (10 lb) since she was last seen 6 months ago. Physical examination of the oral cavity shows no dental caries. Severe pain is reproduced with light touch of the left cheek. Neurologic examination is otherwise normal. Which of the following is the most likely cause of this patient's condition?

Question

A 59-year-old woman comes to the office due to recurrent facial pain for the past month.  The pain occurs only on the left side.  It starts just in front of the ear as a shock-like sensation that quickly radiates down the jaw over 4-8 seconds, then resolves.  It is most commonly triggered by chewing, so the patient sometimes skips meals to avoid the pain.  Vital signs are normal.  The patient has lost 4.5 kg (10 lb) since she was last seen 6 months ago.  Physical examination of the oral cavity shows no dental caries.  Severe pain is reproduced with light touch of the left cheek.  Neurologic examination is otherwise normal.  Which of the following is the most likely cause of this patient's condition?

Quizplus · Accepted Answer

11ec160b_39e3_e274_9249_d383d96c3230_MD0001_00 This patient with unilateral, intermittent, shock-like pain of the left face that lasts several seconds and is triggered by minor stimuli (eg, chewing) likely has trigeminal neuralgia (TN). Characteristic clinical features of TN include the following: Paroxysmal severe attacks of neuropathic pain (eg, shock-like, stabbing) lasting a few seconds to 2 minutes Unilateral pain involving primarily the V2 and V3 distributions of the trigeminal nerve (CN V) Innocuous triggers (eg, chewing, talking, brushing teeth) and allodynia (pain to light touch) Absence of other neurologic deficits on examination The pathophysiology of TN seems to be related to compression of the trigeminal nerve root as it enters the pons, leading to demyelination and atrophy of the nerve. Compression most commonly occurs due to an abnormal vascular loop, neoplastic growth, or multiple sclerosis plaque. (Choice A) Inflammatory degradation of the temporomandibular joint (TMJ) can lead to TMJ disorder, which often causes pain with jaw movement (eg, chewing). However, pain due to the TMJ is classically dull and waxing and waning rather than neuropathic (eg, shock-like). Clicking/popping noises with jaw movement are common, as are ear-related symptoms (eg, ear pain, stuffiness, tinnitus). (Choice C) Reactivation of herpes zoster virus in a sensory ganglion can lead to herpetic neuralgia, which can impact CN V. Dermatomal pain can precede development of the classic vesicular rash by several days. However, seconds-long paroxysms of pain triggered by eating and unaccompanied by a rash after a month are more consistent with TN. (Choice D) Herpesvirus-mediated inflammatory demyelination may underlie the development of Bell palsy (idiopathic palsy of the facial nerve [CN VII]). However, this usually does not cause pain but instead results in unilateral facial weakness. In TN, demyelination and atrophy are due to compression of the nerve root. Educational objective: Trigeminal neuralgia is caused by compression of the trigeminal nerve (CN V) root as it enters the pons, usually by an abnormal vessel loop. This leads to atrophy and demyelination of the nerve and causes short paroxysms of neuropathic pain.

A 59-Year-Old Woman Comes to the Office Due to Recurrent