WBR0576

Author	[[PageAuthor::Rim Halaby, M.D. [1] (Reviewed by Yazan Daaboul, M.D.)]]
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Microbiology, MainCategory::Pathophysiology
Sub Category	SubCategory::Neurology, SubCategory::Infectious Disease
Prompt	[[Prompt::A 55-year-old woman with poor medical follow-up is referred to the neurology clinic when she was found to have an abnormal neurological examination in a local healthcare fair. Upon questioning, the patient reports lower extremity numbness and imbalance for the past 3 months. She also complains of occasional urinary incontinence and shooting pains in her abdomen and back, which she sometimes attributed to indigestion. On physical examination, the physician notices bilateral miotic pupils that are non-reactive to light but are reactive to accomodation. He also notes diminished reflexes in the lower extremities and a wide-based, slapping gait. Which of the following images depict the spinal cord lesions that are most likely responsible for the patient's condition (lesion in red)?]]
Answer A	[[AnswerA::]]
Answer A Explanation	[[AnswerAExp::This image depicts the involvement of the dorsal columns of the spinal cord that house the ascending proprioception and vibration sense pathways classically seen in tabes dorsalis. The dorsal columns are also be involved in other syndromes including subacute combined degeneration seen with vitamin B12 and vitamin E deficiency.]]
Answer B	[[AnswerB::]]
Answer B Explanation	AnswerBExp::This image typically depicts spinal cord lesions of ALS that involve both descending corticospinal tracts, and the anterior horns. The involvement of both these structures is what leads to the combination of UMN and LMN symptoms seen in ALS.
Answer C	[[AnswerC::]]
Answer C Explanation	[[AnswerCExp::This image depicts isolated anterior horn injury usually seen in patients with poliomyelitis or Werdnig-Hoffman syndrome (floppy baby syndrome). Both of these diseases only cause LMN signs due to the lack of involvement of descending motor tracts.]]
Answer D	[[AnswerD::]]
Answer D Explanation	[[AnswerDExp::This image depicts multiple, non-patterned white matter lesions usually seen in patients with multiple sclerosis.]]
Answer E	[[AnswerE::]]
Answer E Explanation	[[AnswerEExp::This image is depicts an expanding central canal compressing adjacent tracts typically seen in syringomyelia. The anterior white commissure is the closest structure which leads to compression of the decussating spinothalamic tracts first.]]
Right Answer	RightAnswer::A
Explanation	[[Explanation::Tabes dorsalis is a neurodegenerative disease seen in tertiary neurosyphilis that involves the posterior columns and roots of the spinal cord. The presentation is usually that of loss of proprioceptive sensations with progressive ataxia that can lead to paralysis if untreated. Lightning-like shooting pains are also common. Physical exam usually reveals a wide based gait, diminished reflexes and loss of vibration and position senses in the lower extremities. Argyll Robertson pupils that are baseline miotic pupils non-reactive to light but reactive to accommodation can also be seen. CSF usually shows leukocytosis >20 cells/mcL and positive VDRL or RPR. Tabes dorsalis is a rare disease since the antibiotic era although some cases can still be seen since the onset of this syndrome is 20-30 years after the initial infection. Treatment with penicillin stops the progression but cannot reverse the damage done. Educational Objective: Tabes dorsalis is disease seen in tertiary syphilis that leads to destruction of the dorsal columns and roots. References: Lanska DJ. The suspension apparatus for tabes dorsalis. Neurology. Apr 12 1999;52(6):1295. Chahine LM, Khoriaty RN, Tomford WJ, Hussain MS. The changing face of neurosyphilis. Int J Stroke. Apr 2011;6(2):136-43. ]]
Approved	Approved::No
Keyword	WBRKeyword::Tabes dorsalis, WBRKeyword::Syphilis, WBRKeyword::Dorsal columns
Linked Question	Linked::
Order in Linked Questions	LinkedOrder::