Pregunta 8. Cuál es el estudio más adecuando?


A 72-year-old woman who presents with a 7-month history of progressive lower extremity weakness reports a dull ache in the legs, especially with ambulation. She had been active and able to exercise, drive, and care for herself, but fell while shopping due to leg weakness and heaviness. Since then, she has needed assistance when walking across a room and now requires a walker and wheelchair. She reports urinary retention beginning 5 months ago and has had two urinary tract infections in the past 2 months. An MRI scan of the spine is shown. Analysis of CSF shows mild leukocytosis but normal cytology, normal levels of protein and glucose, and negative cultures. Results of viral and autoimmune testing are negative, and antibody testing for aquaporin 4 antibody is negative. The patient received pulse IV steroids twice without benefit. Examination reveals moderate to severe weakness of the proximal and distal muscles, with symptoms more prominent on the left side than on the right. Patellar reflexes are increased bilaterally, Babinski reflex is positive on the left side, and results of sensory examination are nonspecific, with deficits noted more distally than proximally. Which of the following diagnostic tests should be ordered?

A. Spinal angiography
B. Paraneoplastic antibody testing
C. Myelin oligodendrocyte glycoprotein antibody
D. Spinal and visually evoked potentials
E. Repeat high volume lumbar puncture with CSF cytology and flow cytometry analysis

Spinal angiography
B. Paraneoplastic antibody testing **
C. Myelin oligodendrocyte glycoprotein antibody
D. Spinal and visually evoked potentials
E. Repeat high volume lumbar puncture with CSF cytology and flow cytometry analysis
** = Your answer

Spinal dural arteriovenous fistulas are abnormal direct connections between a radicular feeding artery and a radiculomedullary vein, resulting in retrograde filling of the coronal plexus around the spinal cord. The fistula is located in the dural sleeve of the nerve root. Shunting of arterial blood flow causes venous congestion, venous hypertension, and progressive myelopathy. Spinal dural arteriovenous fistulas constitute more than 70% of spinal arteriovenous malformations (AVMs) and are thought to be acquired anomalies, unlike intramedullary AVMs. This abnormality predominantly affects men, although the reason for this sex predilection is unknown. The peak incidence of diagnosis is the sixth and seventh decades, and the fistula is most commonly located in the lower thoracic to upper lumbar spine. The resulting venous hypertension affects the entire spinal cord below the level of the fistula.
Symptoms of myelopathy usually start insidiously and progress gradually. Weakness and sensory symptoms in the legs are the most common initial manifestations of the disease. Symptoms are not infrequently asymmetric at onset, but become bilateral and fairly symmetric over time. The leg weakness typically increases with exertion (exertional claudication) and improves with rest. Patients with more advanced cases may have worse symptoms with prolonged standing and relief with recumbency. Leg or back pain occurs in at least 20% of patients at presentation and in a larger proportion over the course of the disease and may mimic a radiculopathy. Ascending paresthesia and dysesthesia in the legs can be mistakenly attributed to peripheral neuropathy. Sphincter problems (i.e., urinary and fecal retention or incontinence) and erectile dysfunction are rare early but very commonly present by the time of yield of the study. Spinal cord edema or ischemia from the effects of venous hypertension manifests as a longitudinally extensive hyperintense signal abnormality on T2-weighted FLAIR sequences throughout the central cord. The edema reaches the conus in most patients. The dilated and tortuous perimedullary vessels associated with the fistula are seen as flow voids, usually located dorsal to the cord.
Contrast-enhanced MR angiography can be helpful to focus the search for the fistula with catheter spinal angiography. Selective digital subtraction angiography is indispensable to confirm the fistula and to precisely define its vascular anatomy, including detailed identification of the feeding arteries and draining vein.
Surgery is durable and safe; successful resolution of the fistula can be achieved in up to 98% of patients with very low morbidity in experienced hands. More recently, endovascular treatment has emerged as a valid alternative to surgery. Liquid embolic material is injected into a feeding artery to occlude the fistula and the proximal part of the draining vein. Symptoms usually either stabilize or improve after treatment of a spinal dural arteriovenous fistula.

* Rabinstein AA. Vascular myelopathies. Continuum Lifelong Learning Neurol. 2015;21(1):67-83.

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