Knowing when imaging is urgent, recommended, and unnecessary is the key to making the right decision for patients with headache.
OJAI, CA—A headache specialist should order imaging studies of a patient if he or she suspects that a headache disorder may have a secondary cause, if a patient’s symptoms are atypical, or if the examination of the patient reveals an unexpected finding, said Benjamin Frishberg, MD, at the Fifth Annual Winter Conference of the Headache Cooperative of the Pacific.
To obtain the best diagnosis, a physician should order the most appropriate imaging study given the circumstances and communicate with the radiologist to get the best results, said Dr. Frishberg, a neuro-ophthalmologist at the Headache Center of Southern California in Encinitas. If the results of the scan do not fit with the clinical picture, or if the physician is looking for specific abnormalities, it is recommended that the clinician either look at the scans personally or engage the radiologist to make sure the right scans were performed and the areas of interest are clearly visible. Dr. Frishberg gave several examples of significant missed imaging findings that resulted from radiologists’ lack of clinical data or improper scan protocols.
When Imaging Is Urgent
The need for imaging studies is urgent under certain circumstances. For example, if the patient has double vision and pain around the eye, he or she needs to be imaged to determine whether the symptoms may result from a partial third-nerve palsy due to an aneurysm.
Likewise, a patient with painful Horner’s syndrome should be imaged promptly, because he or she has “a dissection of the carotid artery until proven otherwise,” said Dr. Frishberg. “Now that we’re aware of that and we have better imaging techniques, we’re finding dissections in patients with Horner’s syndrome who are otherwise asymptomatic,” he added.
Patients with papilledema or with focal neurologic findings that may indicate a problem in the CNS also need imaging studies. Thunderclap headaches have several causes, and many of them are serious, such as subarachnoid hemorrhage, cervical artery dissection, pituitary apoplexy, and venous sinus thrombosis. A patient with a thunderclap headache “needs to be imaged immediately,” said Dr. Frishberg.
When Imaging Is Unnecessary
If a patient has a primary headache disorder such as migraine, then “you don’t need imaging, because, by definition, it’s not caused by anything else,” said Dr. Frishberg. “Neuroimaging is not usually warranted in patients with migraine and a normal neurologic examination,” he added, quoting the American Academy of Neurology practice guideline.
Patients with clear-cut exertional migraine do not need imaging, but if the patient’s exertional headache is not part of migraine, then imaging is warranted, said Dr. Frishberg. Chiari malformation, expansive intracranial lesions, subarachnoid hemorrhage, and sinus disease can cause exertional headaches.
Even if they are not medically necessary, imaging studies also may be requested to satisfy the patient or the patient’s family, or to protect the physician against a malpractice suit.
Imaging in Primary Headache Disorders
Under certain circumstances, imaging is advisable for patients with a primary headache disorder such as migraine. A physician should consider imaging when a patient experiences a significant change in the pattern of his or her migraine. This patient may have a brain tumor or may have developed a disorder unrelated to the migraine. “You always have to … be careful about attributing all of a patient’s symptoms to his or her migraine,” said Dr. Frishberg. Imaging is also recommended for patients who no longer respond to their usual therapy and for patients older than 50 with new-onset headaches, even those that appear to be migraine.
Patients whose headaches have atypical features or do not fit into a defined primary headache disorder also are candidates for imaging. The likelihood of finding significant results is higher in these patients.
Physicians should strongly consider imaging in patients with one of the trigeminal autonomic cephalalgias, because they may result from a pituitary adenoma or other parasellar lesion. A physician should also consider imaging patients with cluster headache, especially if it is the first cluster. “If they’ve had a recurring cluster over years, and it’s unchanged, and they’ve had four cluster periods over six or seven years, I probably would not [order imaging],” said Dr. Frishberg.
A patient with new daily persistent headache (NDPH) should be imaged, because NDPH may have many secondary causes and may result from various disease processes. A physician should not diagnose NDPH until ruling out other organic causes such as sphenoid sinusitis, neoplasms, and chronic meningitis.
Choosing the Right Test
A head CT scan often is the first test that a physician orders. In some cases, no other tests are required. CT angiography can be better than magnetic resonance angiography (MRA) if the physician is looking for intracranial aneurysm or carotid dissection, said Dr. Frishberg.