A 20-year-old woman comes to the physician because of multiple burns on her hands. She says that she gets burned quite often when she cooks, particularly while operating the oven. She also has burned herself when picking up her morning cup of coffee and when testing the water temperature in the shower. The patient is concerned because she cannot feel when objects are "really hot" and often does not notice that she has burns until she looks at her hands. She has no significant past medical history, no recent illnesses, and no sick contacts. Her surgical history is significant only for removal of impacted wisdom teeth 1 year ago. The patient has never smoked, drinks alcohol occasionally, and does not use illicit drugs. Her family history is significant for multiple sclerosis in her mother. Examination shows diminished pinprick and temperature sensation across the upper back, shoulders, and arms bilaterally. Light touch, position, and vibration sense are preserved. Examination of the lower extremities is unremarkable. Damage to which of the following spinal cord areas is most likely responsible for this patient's symptoms?

Question

A 20-year-old woman comes to the physician because of multiple burns on her hands.  She says that she gets burned quite often when she cooks, particularly while operating the oven.  She also has burned herself when picking up her morning cup of coffee and when testing the water temperature in the shower.  The patient is concerned because she cannot feel when objects are "really hot" and often does not notice that she has burns until she looks at her hands.  She has no significant past medical history, no recent illnesses, and no sick contacts.  Her surgical history is significant only for removal of impacted wisdom teeth 1 year ago.  The patient has never smoked, drinks alcohol occasionally, and does not use illicit drugs.  Her family history is significant for multiple sclerosis in her mother.  Examination shows diminished pinprick and temperature sensation across the upper back, shoulders, and arms bilaterally.  Light touch, position, and vibration sense are preserved.  Examination of the lower extremities is unremarkable.  Damage to which of the following spinal cord areas is most likely responsible for this patient's symptoms?

Quizplus · Accepted Answer

11ec160b_39df_4e8b_9249_3730589ee68f_MD0001_00 This patient most likely has syringomyelia, which classically presents with disproportionate loss of pain and temperature sensation (dissociated anesthesia) involving the arms and hands. In syringomyelia, a cerebrospinal fluid-filled cavity called a syrinx usually forms in the cervical region of the spinal cord. These cavities can enlarge over time and destroy adjacent portions of the spinal cord. The areas most commonly damaged are the ventral white commissure and ventral horns. The ventral white commissure is located just anterior to the gray commissure. It is the area of decussation for the fibers of the lateral spinothalamic tract, which transmits pain and temperature sensation from peripheral receptors to the somatosensory cortex. Destruction of the ventral white commissure leads to loss of pain and temperature sensation bilaterally over the affected dermatomes (starting 1 to 2 levels below the lesion, as the axons briefly ascend in the zone of Lissauer before decussating). Touch, vibration, and position senses are preserved as the dorsal columns remain intact. (Choice B) The ventral horns contain lower motor neurons that receive impulses from the lateral corticospinal tract. Damage to the ventral horn can occur in syringomyelia, but would cause flaccid paralysis and atrophy of the intrinsic hand muscles (not loss of pain and temperature sensation). (Choice C) The ventral spinothalamic tract is located in this area and transmits crude touch and pressure sensation. It should not be confused with the lateral spinothalamic tract, which carries pain and temperature sensation. (Choice D) After decussating in the ventral white commissure, axons of the lateral spinothalamic tract ascend to the brain in the lateral funiculus. Damage to this area would cause contralateral loss of pain and temperature sensation distally, beginning 1 to 2 segments below the lesion. However, bilateral sensory loss would not occur with damage to this area. (Choice E) The dorsal horn contains first order axons and second order neurons that transmit sensory input from peripheral receptors. Damage to the dorsal horn would likely result in unilateral loss of all sensation over the affected dermatomes. (Choice F) The dorsal column contains both the gracile and cuneate fasciculi. They are formed by axons of first-order neurons of the dorsal column pathway. This tract is the primary mediator of proprioception, vibration, and tactile sensation. Educational objective: Syringomyelia is characterized by the formation of a cavity (syrinx) in the cervical region of the spinal cord. The syrinx damages the ventral white commissure, leading to bilateral loss of pain and temperature sensation that is limited to the affected levels (typically the arms and hands); distal sensation is preserved. Destruction of the motor neurons in the ventral horns (due to extension of the syrinx) results in flaccid paralysis and atrophy of the intrinsic muscles of the hand. __________ References: Syringomyelia. (http://www.ncbi.nlm.nih.gov/pubmed/8954460)

A 20-Year-Old Woman Comes to the Physician Because of Multiple