A 60-year-old man comes to the office due to difficulties in tasting food. He says, "All food now tastes bland," and he is unable to enjoy different flavors during meals. Two months ago, the patient had a traumatic brain injury after a head-on motor vehicle collision. He was in a coma for several days and, after regaining consciousness, began having severe headaches and impaired taste. The headaches have improved, but he continues to have difficulty tasting food. The patient has no visual concerns, slurred speech, trouble swallowing, vertigo, or extremity weakness or numbness. He is a truck driver and has a history of heavy tobacco use for many years. Vital signs are within normal limits. Physical examination shows no focal motor deficits. Which of the following is the most likely cause of this patient's current symptoms?

Question

A 60-year-old man comes to the office due to difficulties in tasting food.  He says, "All food now tastes bland," and he is unable to enjoy different flavors during meals.  Two months ago, the patient had a traumatic brain injury after a head-on motor vehicle collision.  He was in a coma for several days and, after regaining consciousness, began having severe headaches and impaired taste.  The headaches have improved, but he continues to have difficulty tasting food.  The patient has no visual concerns, slurred speech, trouble swallowing, vertigo, or extremity weakness or numbness.  He is a truck driver and has a history of heavy tobacco use for many years.  Vital signs are within normal limits.  Physical examination shows no focal motor deficits.  Which of the following is the most likely cause of this patient's current symptoms?

Quizplus · Accepted Answer

11ec160b_35ca_b119_9249_01bc1397e3d9_MD0001_00 This patient has a decreased perception of flavors after traumatic brain injury. The perception of flavor is dependent on both smell and taste, with smell being more important. Patients with anosmia (loss of smell) often describe difficulties with taste, even if taste sensation is intact. The perception of smell is mediated by odorant molecules that bind to olfactory chemoreceptor cells in the nasal mucosa. Axons of the chemoreceptor cells make up the olfactory nerve (CN I) rootlets, which project through the cribriform plate of the ethmoid bone to synapse on the glomeruli of the olfactory bulb. The olfactory bulb then projects second-order axons to the primary olfactory cortex in the medial temporal lobe via the olfactory tract. Head trauma can cause anosmia when acceleration-deceleration forces lead to avulsion of the olfactory nerve rootlets as they transverse the cribriform plate. (Choice A) The anterior temporal lobe is important for semantic memory; as a result, injury to this brain region typically results in impaired comprehension about the meaning of words, pictures, and objects. (Choice C) Dorsolateral medulla infarction causes Wallenberg syndrome. This condition is characterized by vertigo/nystagmus, ipsilateral cerebellar signs (eg, ataxia, dysmetria), loss of pain/temperature sensation in the ipsilateral face and contralateral body, bulbar weakness (eg, dysphagia), and ipsilateral Horner syndrome (miosis, ptosis, anhidrosis). (Choice D) The lingual nerve is a branch of the mandibular division of the trigeminal nerve (CN V3) that provides somatic sensation to the anterior two-thirds of the tongue. Fibers of the chorda tympani nerve, a branch of the facial nerve (CN VII), also travel with the lingual nerve to relay taste from the anterior two-thirds of the tongue. If taste disturbances were due to injury of the lingual nerve, tongue numbness would also be present. (Choice E) Sphenoid bone fractures are associated with damage to the optic nerve (CN II), pituitary gland injury, and leakage of cerebrospinal fluid into the sphenoid sinus. Educational objective: Olfactory signals are relayed via the olfactory nerve (CN I) through the cribriform plate to the olfactory bulb, which then projects to the primary olfactory cortex in the medial temporal lobe. Head trauma can tear olfactory nerve (CNI) rootlets as they cross the cribriform plate, causing anosmia. Anosmia is often interpreted by patients as loss of taste.

A 60-Year-Old Man Comes to the Office Due to Difficulties