 |
Headache
Headache is one of the most frequent presenting complaints seen
in the practitioner's office. In fact, headaches are one of the
top ten reasons for outpatient visits in the United States (1).
Headaches are seen in both adults and children, with about 5%
of adults reporting at least one almost unbearable headache within
the past year (2). They are also common in children, with 60%
reporting headaches, 10% frequently (3). Migraines are also common,
with 18% of adult females and 6% of adult males reporting at least
one migraine a year (4). They are also experienced by 4%-7% of
adolescents and 1%-3% of children under 7 (3,5).
Imaging Yield
Rather than rush to image all patients presenting with headache,
it is important to understand that the yield of imaging studies
for patients with headache or migraine but no neurologic findings
on exam is extremely low. A meta-analysis reviewed multiple articles
published between 1974 and 1991 and looked at the yield of CT
and MRI scans in patients presenting with an isolated headache
or migraine symptoms and no neurological findings (6). Of the
1,825 scans performed for isolated headache, the overall positive
rate was 2.4%. The yield of 1,440 scans performed on patients
presenting with various types of migraine was even lower at 0.4%.
Many of the findings were not treatable and had little or no relationship
to the headache or impact on the patient's prognosis. Furthermore,
the authors questioned whether discovering these lesions, prior
to the patient manifesting objective neurologic findings would
have ever impacted the patients health outcomes.
A subsequent analysis was added to this study for a total of
3,026 CT or MRI scans for patients with unspecified headache and
1,440 scans for patients with migraine symptoms (7). The yield
was similarly very low.
Costs
Given a presumed cost for a CT scan of the head of $500 and for
an MRI of the brain of $900, based on the yields listed above
(6), it can be estimated that the cost per positive outcome would
be $112,125 per CT scan and $252,281 per MRI for patients presenting
with migraine symptoms, and $21,220 per positive CT scan and $47,745
per positive MRI for patients presenting with unspecified headache.
Headache Categories
Because of the ubiquitous nature of headaches in the adult and
pediatric population, the practitioner must become familiar with
the etiology of headache. According to the International Headache
Society, there are over 300 causes of headache (8). These range
from primary headache disorders such as tension headache, cluster
headache and migraine, to headaches associated with vascular and
non-vascular headache disorders, as well as those associated with
metabolic disorders and medication use. Many of these can be safely
diagnosed and treated without the use of an imaging study.
Table I contains a broad summary of general headache categories.
Table I
|
Headache Categories |
|
Primary Headache Disorders |
Tension-type, cluster,
migraine, migraine variant, cold stimulus |
| Vascular
Lesions |
AVM, aneurysm, vasculitis,
cerebrovascular disease, intracerebral hemorrhage, stroke,
temporal arteritis |
| Space-Occupying
Lesions |
Brain tumors, infectious
processes (e.g., cryptococcus), hematoma, sarcoid, colloid
cyst |
| Metabolic/Systemic
Abnormalities |
Fever, systemic infection,
hyponatremia, hyperuricemia, hypoxia |
| Infectious |
Meningitis, encephalitis,
intracranial abscess |
| Medications
/ Substances |
Nitroglycerine and other
prescription drugs, analgesic/drug withdrawal |
| Postconcussive |
|
| Referred / Neuralgic |
Sinusitis, cervical pain,
temporomandibular joint disorders, ophthamologic lesions,
trigeminal and other neuralgias |
Patient Evaluation
A thorough medical history and physical exam, including a neurologic
exam, are crucial to the evaluation of a patient with headache.
Imaging studies should not be used as a substitute for a proper
history and physical. Practitioners not comfortable evaluating
and treating patients with headache complaints should consider
referring them to the appropriate specialists.
Practitioners should also be familiar with the nature and
symptoms of primary headache disorders and the therapeutic and
prophylactic medications and lifestyle changes recommended to
treat these disorders. Selection of the appropriate headache management
modalities is dependent on a correct diagnosis.
"Imaging studies should
not be used as a substitute for a proper history and physical"
Frequently, primary headache disorders fail to respond to medication
because the prescribed medication is incorrect for that type of
headache. Breakthrough migraines may result from the sub-optimal
selection of migraine therapies including prophylactic medications
and/or poor patient compliance to lifestyle changes. (9)
If a headache persists in a compliant patient on appropriate conventional
therapy, the practitioner should reassess his initial diagnosis
and consider the possibility of an underlying disorder.
Red Flags
Certain findings are considered "red flags" when it comes to
headaches because they are more likely to be associated with an
underlying pathology on imaging studies. An imaging study may
be indicated if any of the findings listed in Table II are associated
with a headache.
Age may be one of several factors in determining the necessity
for an imaging study. For example, it is uncommon for individuals
over 50 years of age to develop migraine or cluster-type headaches.
Also, the incidence of headache caused by serious conditions is
increased tenfold after age 65 (7). Other than common tension-type
headaches, it is essential to evaluate older patients for one
of many secondary etiologies of headache, such as medication-related,
metabolic, uncontrolled hypertension, temporal arteritis, systemic
disease, or intracranial mass lesion.
Table II
Headache "Red Flags"
(In Adults)
|
| Focal neurologic
abnormalities not consistent with a typical migraine aura |
| Papilledema; mental status changes |
| True vertigo with
or without unilateral sensorineural hearing loss, tinnitus
and/or ataxia |
| Sudden onset of severe headache |
| New onset headache
in patients over 50 years old |
| Progressively worsening moderate to
severe headache, especially if not responsive to conventional
pain therapies |
| Fever and/or stiff
neck |
| Underlying medical condition associated
with intracranial processes (metastatic cancer, AIDS, neurofibromatosis) |
| New or "breakthrough"
onset seizures |
| Nausea and or vomiting not explained
by an underlying systemic process (e.g., gastritis) |
Guidelines
Guidelines have been proposed to assist practitioners in their
decision on whether to order diagnostic imaging studies in the
evaluation of headache. The Quality Standards Subcommittee of
the American Academy of Neurology offers the following guidelines
(10):
"In adult patients with recurrent headaches that
have been defined as migraine -- including those with visual aura
-- with no recent change in pattern, no history of seizures, and
no other focal neurologic signs or symptoms, the routine use of
neuroimaging is not warranted. In patients with atypical headache
patterns, a history of seizures, or focal neurologic signs or
symptoms, CT or MRI may be indicated."
A four-year retrospective study done at Boston Childrens Hospital,
Harvard Medical School, in Boston reviewed the outcomes of 315
CT or MRI scans performed on children with no known underlying
neurologic disorders with the chief complaint of headache (11).
Based on their results (a 4% positive yield), the authors suggested
the following guidelines for selecting neuroimaging studies in
children with headaches:
Table III
| Headache "Red Flags" (In Children) |
| Persistent headache
of <6 months duration and not responsive to treatment |
| Abnormal neurologic findings, especially
papilledema, nystagmus, gait or motor abnormalities |
| Persistent headache
and an absent family history of migraines |
| Persistent headache and confusion,
disorientation or emesis |
| Awaken from sleep
or occur on awakening |
| Family history of conditions associated
with CNS lesions or laboratory findings suggestive of CNS
involvement |
Radiology 1997; 202:819-827
Conclusion
Headache is a symptom seen very often in the practitioner's office.
Most headaches are the result of primary headache disorders such
as tension-type headache or migraine and may not require further
neuroimaging evaluation. The yield of imaging studies in the evaluation
of headache and migraine without accompanying focal neurologic
findings is very low at 2.4% and 0.4% respectively. These findings
led to a recommendation by the American Academy of Neurology that
the routine use of neuroimaging procedures is not indicated in
patients presenting with symptoms consistent with typical migraine
without associated seizures or neurologic deficits.
Appropriate evaluation of patients presenting with headache includes
a complete medical history and physical examination, including
a thorough neurologic exam. Imaging studies should not be used
as a substitute for a proper history and physical examination.
According to the International Headache Society, there are over
300 known causes of headache. Practitioners should familiarize
themselves with how these different types of headaches present
and are treated. They should become well-versed in the treatment
of common primary headache disorders, such as tension-type headaches
and migraines, to ensure that unresponsive and breakthrough headaches
do not simply reflect inadequate treatment regimens.
In isolation, symptoms of the typical tension-type or migraine
headache are rarely associated with a serious underlying cause
(12). Certain signs or symptoms can serve as red flags for the
more serious underlying headache etiologies. These may include
vertigo, mental status changes, focal neurologic findings, papilledema
and others.
Age also plays a role in the decision to order an imaging study.
For example, headaches are less common and intracranial lesions
more common in young children, so the threshold for ordering imaging
studies in this age group may be lower. A recent Harvard study
has suggested some guidelines on the selection of neuroimaging
studies in children presenting with headaches (Table III).
Patients over age 50 also present with some unique characteristics.
New onset migraine and cluster-type headaches are less common
in this age group. This age group is also likely to have underlying
medical conditions associated with headaches, such as temporal
arteritis, intracranial lesions, or cerebrovascular disease affecting
the Circle of Willis. If no etiology is apparent on full medical
history and physical examination, the threshold to order an imaging
study in this age group is lower.
Practitioners not comfortable evaluating and treating patients
with headache complaints should consider referring them to appropriate
specialists. A variety of imaging modalities is available to evaluate
headache patients - CT scan of the brain, MRI of the brain, MRI
of the orbits, MRA, cerebral angiogram, MRI of the cervical spine,
CT scan of the sinuses, etc. Familiarity with the proper evaluation
of headaches will help practitioners determine when imaging is
indicated and which exam is the most cost-effective study.
We appreciate the editorial assistance of:
Richard Toran, M.D.
Chief of Neurology
Newton-Wellesley Hospital
Assistant Professor of Neurology
Tufts School of Medicine
References
- Kroenke K, Mangelsdorff AD. Common symptoms in ambulatory care:
incidence, evaluation, therapy, and outcome. Am J Med 1989;86:262-266.
- Newland C, Illis L, Robinson P, Bachelor B, Walters W. A survey
of headache in an English city. Research and Clinical Studies
in Headache 1978; 5:1-20.
- Bille B. Migraine in school children. Acta Paediatr Scand 1962;51(Suppl
136):1-151 in: Maytal J, Bienkowski RS, Patel M, Eviatar L. The
value of Brain Imaging in Children with Headaches. Pediatrics
1995; 96(3):413-416.
- Stewart W, Lipton R, Celentano D, Reed M. Prevalence of migraine
headache in the United States. JAMA 1992;267:64-69.
- Sillanpaa ML. Headache in children. In Olesen J, (ed): Headache
classification and epidemiology. New York, NY: Raven, 1994;273-281.
- Frishberg BM. The utility of neuroimaging in the evaluation
of headache in patients with normal neurologic examinations. Neurology
1994; 44:1191-1197.
- Evans RW. Diagnostic testing for the evaluation of headaches.
Neurologic Clinics 1996; 14(1):1-26.
- Headache Classification Committee of the International Headache
Society: Classification and diagnostic criteria for headache disorders,
cranial neuralgia and facial pain. Cephalgia 1988; 8(suppl 7):1-96.
- Loder EW. Migraine Management: An overview of nonpharmacologic
and pharmacologic interventions. Postgraduate Medicine (A special
report), January 1998; 13-19.
- Quality Standards Subcommittee of the American Academy of Neurology.
Practice parameter: the utility of neuroimaging in the evaluation
of headache in patients presenting with normal neurologic examinations
(summary statement). Neurology 1994:44(7)1353-1354.
- Medina LS, Pinter JD, Zurakowski D et al. Children with Headache:
Clinical predictors of surgical space-occupying lesions and the
role of neuroimaging. Radiology 1997; 202:819-824.
- Dodick D. Headache as a symptom of ominous disease. Postgraduate
Medicine 1997; 101(5):46-64.
For questions or comments about our diagnostic imaging educational
program or documents, please email web_comments@americanimaging.net
|
|
