Neuroimaging in Headache Disorders: When Is It Necessary?

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The use of neuroimaging remains at the discretion of the clinician, necessitating more research to improve clinical understanding of headache disorders.
The use of neuroimaging remains at the discretion of the clinician, necessitating more research to improve clinical understanding of headache disorders.

The World Health Organization defines headache disorders as any illness characterized by frequent headaches, the most common being migraines, tension-type headaches, cluster headaches, and medication overuse headaches.1 In the United States, more than 15% of adults have severe headaches or migraines, with higher prevalence among women and those under 65 years of age.2 With such high prevalence, headache disorders make up a significant amount of a clinician's workload.

Diagnosing Headache Disorders

Guidelines set by the American Academy of Neurology (AAN) state3:

“The EEG [electroencephalogram] is not useful in the routine evaluation of patients with headache (guideline). This does not exclude the use of EEG to evaluate headache patients with associated symptoms suggesting a seizure disorder, such as atypical migrainous aura or episodic loss of consciousness. Assuming head imaging capabilities are readily available, EEG is not recommended to exclude a structural cause for headache (option).”

Despite this guidance and that headache disorders can be diagnosed in several ways, neuroimaging remains the go-to tool for many clinicians, raising concerns about its overuse. Given the distress these invasive tests can cause to patients and the cost to healthcare systems, clinicians must weigh the pros and cons of using neuroimaging as a diagnostic tool on a case-by-case basis.

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Factors to Consider in Headache Disorder Diagnosis

Neuroimaging is considered unnecessary for primary headache such as migraine, cluster headache, and tension-type headache.1 According to Oved Daniel, MD, a neurologist and headache specialist at Laniado Hospital in Israel, “Usually, no investigations are necessary, as the diagnosis of a migraine is clinical. However, in some atypical cases, we might want to send the patient for a CT scan or an MRI to rule out migraine-mimicking etiologies, especially if there are focal neurologic signs on the patient's neurological examination.”

Instead of taking the default option of ordering neuroimaging, clinicians are advised to first examine patient history and physical findings, looking for red flags that may require further examination.4

Patient history characteristics indicating neuroimaging necessity:

  • Worsening headaches
  • Prolonged fever
  • New headaches in a person with cancer
  • Headaches in patients with a weak immune system
  • New headaches in people over 50 years old
  • Medication is ineffective
  • Prolonged headache after an injury

Physical characteristics indicating neuroimaging necessity:

  • Eye swelling or pupil abnormalities
  • Double vision or vision loss
  • Abnormal reflexes
  • Unsteady walking
  • Weakness on one side of the face or body
  • Confusion

Most diagnosed headaches tend to be primary, so clinicians look for clues that may indicate a more serious secondary headache. Even when red flags are identified, some secondary headaches, such as headaches caused by sinusitis, can be easily diagnosed without neuroimaging.

Advantages and Disadvantages of Neuroimaging

MRIs, CT scans, EEGs, and other neuroimaging techniques have facilitated a greater understanding of the human brain and neurologic disorders.5,6 In the case of headache disorders, these scans are advantageous in situations where secondary disorders such as brain tumors and Chiasmal lesions present the same symptoms as migraines, cluster headaches, or tension-type headaches.7 In such cases, neuroimaging is required as a more sensitive diagnostic tool.

However, there are certain risks involved in the use of neuroimaging. When brain scans are not carried out effectively, there is the risk of providing inaccurate information to patients, leaving them unnecessarily worried or underconcerned, depending on the situation. The accuracy of the scan often depends on the quality of the imaging machine and the expertise of the operator. Even with the right conditions, false or misleading results may still occur. Exposure to radiation, allergic reaction to mediums, and necessary sedation for patients who feel claustrophobic can also lead to further complications. Although neuroimaging can be a cost-effective method of diagnosing life-threatening illnesses, overuse in headache disorders is driving up costs for both patients and healthcare providers.

Frequency of Neuroimaging in Hospitals

Findings from a study conducted in a pediatric hospital in the midwestern United States support the need to reduce unnecessary neuroimaging.8 A total of 53 patients underwent neuroimaging for headache complaints, and only two (3.8%) results showed significant intracranial findings requiring neurosurgical intervention. Another study, conducted in the United Kingdom, showed that headache on wakening (HoW) and sleep interruption secondary to headache (SIH) are most likely caused by primary headaches if the patient has a normal clinical and neurologic history.9 Of the 102 pediatric (ages 5-17) patients surveyed, 79 (77%) had HoW, 19 (19%) had SIH, and 4 (4%) presented with both HoW and SIH. Eventual diagnosis included migraines (66%), tension-type headaches (16%), headaches caused by medication abuse (11%), and sinusitis (1%). A total of 101 of these patients underwent neuroimaging. Normal results were found in 97 of the patients, and scans in the remaining 4 showed nonsignificant abnormalities. With no significant outcome from the scans, it was concluded that patient history would have been enough to form a diagnosis.

An even more comprehensive study was conducted among adults in a Chinese hospital.10 A total of 2140 subjects, separated into 1070 healthy controls and 1070 people with primary headache, underwent MRI and CT scans. Only 4 (0.58%) patients with primary headache and 5 (0.73%) healthy controls had significant abnormalities, suggesting that neuroimaging is unnecessary for patients with established primary headache disorders.

Although many studies have demonstrated the overuse of neuroimaging in headache disorders, the rate at which brain scans are conducted remains high. There are 2 key reasons for this:

1. Patient Pressure

Patients presenting with symptoms of migraine and other primary headache disorders may insist on a brain scan for their own peace of mind. Because MRIs are covered by insurance only if recommended by the clinician,11 patients often place pressure on their healthcare provider to authorize the procedure.

2. Defensive Diagnosis

Many clinicians practice a defensive approach to headaches, using a process of elimination. When patients present with headache symptoms, neuroimaging is carried out to eliminate the possibility of secondary headaches before settling on a primary headache diagnosis. This approach is more common among physicians who are inexperienced in diagnosing headache disorders.

Curbing the Use of Neuroimaging

The use of neuroimaging as a diagnostic tool remains at the discretion of the clinician, necessitating more research to improve clinical understanding of primary and secondary headaches. In particular, greater emphasis needs to be placed on examining patient history and identifying red flags. Education could also help ease patient pressure to use neuroimaging and clinician tendency to take a defensive approach to diagnosis.

References

  1. World Health Organization. Headache disorders.  http://www.who.int/news-room/fact-sheets/detail/headache-disorders. April 8, 2016. Accessed November 21, 2018.
  2. Statista. Headache and migraine – Statistics & Facts. https://www.statista.com/topics/1974/headache-and-migraine/. 2018. Accessed November 21, 2018.
  3. American Academy of Neurology. The electroencephalogram in the evaluation of headache (summary statement). Report of the Quality Standards Subcommittee of the American Academy of Neurology. Neurology. 1995;45(7):1411-1413.
  4. Frishberg B. Spotlight On: Headache, MRI and Brain Imaging. American Migraine Foundation. https://americanmigrainefoundation.org/resource-library/headache-mri-and-brain-imaging/. Accessed November 21, 2018.
  5. Fujimoto J, Ma J, Kuo AA. Utilization and cost-effectiveness of head imaging for acute and chronic headaches in the primary care setting. Proceedings of UCLA Healthcare. 2017;21.
  6. Russo A, Silvestro M, Tessitore A, Tedeschi G. Advances in migraine neuroimaging and clinical utility: from the MRI to the bedside. Expert Rev Neurother. 2018;18(7):533-544.
  7. Francis M. Neuroimaging in headache disorders. J Headache Pain. 2017;2(1):1-2.
  8. Cain MR, Arkilo D, Linabery A, Kharbanda AB. Emergency department use of neuroimaging in children and adolescents presenting with headache. J Pediatr. 2018;201:196-201.
  9. Ahmed M, Ramseyer-Bache E, Taylor K. Yield of brain imaging among neurologically normal children with headache on wakening or headache waking the patient from sleep. Eur J Pediatr Neurol. 2018;22(5):797-802.
  10. Wang R, Liu R, Dong Z, et al. Unnecessary neuroimaging for patients with primary headaches [published online August 23, 2018]. Headache. doi: 10.1111/head.13397
  11. Cross J. Does Medicare Cover MRI Scans? Medicare.com. https://medicare.com/coverage/does-medicare-cover-mri-scans/. Updated October 20, 2018. Accessed November 21, 2018.

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