A 61 y.o. female has had a COPD exacerbation x several weeks

She was watching the superbowl, using crack cocaine and heroin and on returning home developed lightheadedness and tingling on the L side of her body.  She passed out on her lawn when arriving home and was incontinent of stool.  A TPA page was called on arrival in the ED. Head CT was negative.

 What do you notice on her chest CT?

What do you notice on her chest CT?

Our patient had a saddle embolus. In addition to her strange presentation, more history was obtained .  She had a myelodysplastic disorder and was hypercoagulable.  She had a previous PE and was supposed to be on Coumadin  which she had not taken in over a week.  She also had a clot while therapeutic on Coumadin so an IVC filter was placed on this admission. 

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The patient had persistent L sided weakness and tingling and although her MRI was neg she was felt to have a stroke.  How common is a stroke with negative diffusion weighted MRI? An “invisible stroke?”

There has been a significant increase is the use of MRI in the diagnosis of stroke.  It was thought at one time to be 88-100% sensitive for diagnosing stroke but recent evidence shows diffusion weighted MRI fails to identify stroke in 30% of cases.  The specific areas where it fails are in three categories: the posterior fossa, the brainstem, and in hyperacute ischemia( within six hours of symptoms). These patients with negative imaging have the same outcomes as strokes with positive imaging; persistent deficits and risk of recurrent strokes.

The reason for “invisible strokes” may be that the reduction in cerebral blood flow required to initiate cell swelling( and a positive MRI)  is more severe than that required to produce neurologic symptoms.

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Case thanks to Dr. Ruoff, with stroke information supplied by Dr. Panagos.