A 35-year-old man injured his thoracic spine in a motor vehicle accident 2 years ago. Initially he had a bilateral spastic paraparesis and urinary urgency, but this has improved. He still has pain and thermal sensation loss on part of his left body and proprioception loss in his right foot. There is still a paralysis of the right lower extremity as well. This patient most likely has which of the following spinal cord conditions?
a. Brown-Séquard (hemisection) syndrome
b. Complete transection
c. Posterior column syndrome
d. Syringomyelic syndrome
e. Tabetic syndrome
the answer is below…
The United States Medical Licensing Examination, or USMLE for short, is a three-part licensing examination that is required in order to receive a license to practice medicine within the United States.
The USMLE assesses a physician’s ability to apply knowledge, concepts, and principles, and to determine fundamental patient-centered skills that are important in health and disease and that constitute the basis of safe and effective patient care.Examination committees composed of medical educators and clinicians from across the United States and its territories prepare the examination materials each year.
This exam is designed by the Federation of State Medical Boards and the National Board of Medical Examiners to determine whether or not an individual understands and can apply the knowledge necessary to practice medicine safely and intelligently.
The USMLE is actually comprised of three different exams that are referred to as steps, which examine the individual’s knowledge of specific topics related to the field of medicine such as basic science, medical knowledge, medical skills, clinical science, and the application of all of these skills and areas of knowledge in the medical field.
All three steps of the USMLE include a series of computerized multiple-choice questions, but the format of the exam and the information covered in each multiple-choice section is different for each step of the USMLE. The USMLE Step II also has a clinical skills portion that examines an individual’s ability to work with real patients and the USMLE Step III has a computerized patient simulation portion in addition to the multiple-choice section of the exam. In order for an individual to receive a license to practice medicine, the individual must pass all three steps of the USMLE.
The correct answer is a; Brown-Séquard (hemisection) syndrome.
Hemisection of the spinal cord results in a contralateral loss of pain and thermal sensation due to spinothalamic damage, and ipsilateral loss of proprioception due to posterior column damage. There is also an ipsilateral motor paralysis due to destruction of the corticospinal and rubrospinal tracts as well as motor neurons. Complete transection of the spinal cord would cause a bilateral spastic paralysis, and there would be no conscious appreciation of any cutaneous or deep sensation in the area below the transection. Posterior column syndrome would result in a bilateral loss of proprioception below the lesion, with relative preservation of pain and temperature sensation. Syringomyelic syndrome results from a lesion of the central gray matter. Pain and temperature fibers that cross at the anterior commissure are affected, which may result in bilateral loss of these sensations over several dermatomes. However, tactile sensation is spared. The most common cause of this type of syndrome is syringomyelia. Trauma, hemorrhage, or tumors are other possible etiologies. If the lesion becomes large enough, then other spinal cord systems become affected as well. Tabetic syndrome results from damage to proprioceptive and other dorsal root fibers. It is classically caused by syphilis. Symptoms include paresthesias, pain, and abnormalities of gait. Vibration sense is most affected.