I had a thallium stress test approximately three months ago and developed a constant headache a few hours afterward that I had never experienced before. There is no doubt that the thallium caused the headache, but three months later I still have the same constant headache.
Is there any chance that the thallium could still be in my system,
causing the headache? And if not, is there any knowledge of what the thallium could have triggered or damaged to cause such condition?
Thallium-induced headache as part of a stress test for
myocardial perfusion is unlikely to occur. 210Tl (thallium-210) doses used for
myocardial perfusion exams in the setting of rest only (with Cardiolite or
Myoview for stress imaging) or stress and rest are very small. Headache from thallium
is typically only seen in high doses or chronic exposure and is in the spectrum
of thallium poisoning. A constellation of symptoms from a high or chronic
exposure to thallium includes hair loss, gastrointestinal upset, headache, and
skin changes (limited list). The symptoms are typically not subtle. A headache
alone is uncommon and is limited due to the rapid clearance of the thallium via
the urine stream. 210Tl has a biologic half-life on the order of three
to eight days; thus, even in the setting of acute exposure, symptoms abate in a
timely manner.
However, myocardial perfusion exams have two components: the
imaging tracers and the stress modality. The stress portion of the test is
performed using either an exercise treadmill, vasodilators (Adenosine,
Persantine, Lexiscan), or Dobutamine. All the stress modalities can cause a
wide variety of symptoms including a headache; but again, these typically occur
up to several hours after the stress test.
Unfortunately, the data do not support either thallium
(assuming no toxic exposure given no other submitted side effects, as they would
not be subtle) or the stress test portions of the myocardial perfusion exam as
a root cause of your ongoing headaches.
Headache causes can sometimes, frustratingly, be very tricky
to pin down. There are simple causes such as hypoglycemia or mild dehydration
ranging to severe conditions such as subarachnoid bleeding (bleeding in the
brain) to psychological conditions. Careful documentation of the ebbs and flows
of the headaches, the pattern of pain, and what makes them better or worse can
be helpful in discussing the cause of your specific situation with your primary
care doctor and/or neurologist.
Cameron Foster, MD
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