A thorough history and physical exam are indispensable in the diagnosis of chronic daily headaches. As noted above, a chronic headache should have 15 or more episodes per month for at least 3 months. One should determine the frequency, intensity, characteristics of the pain, as well as the aggravating and alleviating factors. Many headache types involve ipsilateral autonomic symptoms such as lacrimation, conjunctival injection, conjunctival edema, ptosis, miosis, nasal congestion, rhinorrhea, etc.

A thorough medication reconciliation, including over-the-counter analgesics, is essential. Patients with medication-overuse headaches often have a primary headache disorder, and they frequently use pain medications.[15] Medication classes may include non-steroidal anti-inflammatory drugs (NSAIDs), triptans, ergotamines, opioids, or a combination of multiple analgesics. Key historical features include morning headaches, the onset of headaches when medication is delayed, and relief when medication is taken.[16]

Comorbidities, sleep history, and family history of headaches should also be noted. A secondary headache disorder should be excluded from the history and examination. 

Recognition of headache "red flags" is a critical piece in identifying secondary headaches and ordering additional diagnostic testing. Those "red flags" include:[17]

• Age above 50
• Significant change in prior headache pattern
• Severe, "thunderclap" headache
• Systemic illness signs such as fever
• Known illness which increases the risk for secondary headaches such as cancer or HIV
• Neurologic symptoms 
• Headaches associated with Valsalva maneuvers

Physical exam findings concerning secondary headache causes include focal neurological deficits, papilledema, bitemporal hemianopia, homonymous hemianopia, decrease visual acuity or increased pain with the Valsalva method.

Primary chronic headaches often lack physical findings but may have autonomic activation or muscle tenderness in the occipital or cervical regions.

In a straight-forward chronic primary headache disorder, further evaluation may not be warranted, but many clinicians will advise for baseline laboratory testing and brain imaging to exclude the secondary treatable causes. 

Laboratory workup includes a complete blood count to look for infection. Erythrocyte sedimentation rate (ESR) is increased in giant cell arteritis and other vasculitides. A metabolic panel to look for metabolic causes of headache, and endocrine testings to look for pituitary gland abnormalities.

Magnetic resonance imaging (MRI) of the brain is the imaging modality of choice.[18] A contrast study is often recommended to increase the sensitivity and specificity to detect structural abnormalities. A need for vascular imaging is based on the differential diagnosis. Further studies may be warranted depending upon the underlying cause. These may include positron emission tomography (PET) scan, magnetic resonance spectroscopy (MRS), and/or biopsy. A lumbar puncture may be required if there is suspicion of a CNS infection or idiopathic intracranial hypertension.

Treatment and management of chronic headache disorders depend upon the underlying etiology and may require an interprofessional approach.

A patient should maintain a headache journal that will document their headache episodes and any accompanying triggers. If found, stressors should be avoided or minimized. 

Chronic Migraine

• Chronic migraine treatment should begin with setting the expectation that headache frequency and severity will decrease, but headaches will not be eliminated.
• The patient should be counseled that high caffeine intake, sleep deprivation, overuse of analgesics, and comorbid conditions can worsen chronic migraines.
• Prophylactic pharmacologic treatment should be used. First-line therapy includes beta-blockers, anticonvulsants, and antidepressants. The most commonly used medications are propranolol, topiramate, and amitriptyline.[19]
• Botulinum toxin A is a Food and Drug Administration (FDA) approved treatment for chronic migraines and is considered second-line therapy.
• Monoclonal antibodies that target calcitonin gene-related peptide (CGRP) are the newest development in chronic migraine treatment. Erenumab, fremanezumab, and galcanezumab are approved for chronic migraines, which have failed to respond to other treatments[19].
• Triptans, steroids, NSAIDs, and opioids are often used to abort acute episodes, but routine use of these medications increases the risk of developing a medication-overuse headache.
• Patients may also benefit from psychological counseling if anxiety or depression is present.
• Manual medicine, such as spinal manipulation and trigger point treatment, may be used as a complementary or alternative therapy.[20]
• In drug-resistant cases, invasive procedures such as sphenopalatine ganglion blockade and occipital nerve blockade may be tried with variable results. Deep brain stimulation (DBS) is also used in some treatment-resistant cases.[21][22] 

Chronic Tension Headache

• Amitriptyline, a tricyclic antidepressant, is recommended as the first-line treatment for chronic tension headaches.
• Amitriptyline, in addition to inhibiting reuptake of serotonin and noradrenaline, also reduces tenderness in pericranial muscles.
• Tricyclic antidepressants increase the risk for cardiac arrhythmia, and patients should be screened for cardiovascular disorders prior to initiating therapy. Patients over 40 should undergo an ECG.
• Anticonvulsants, such as topiramate and gabapentin, can be considered as second-line treatment.
• Addressing the potential musculoskeletal causes of tension headache, treatment with physical therapy, acupuncture, trigger point injections, spinal manipulation, or muscle relaxants may be beneficial.[23]
• Behavioral therapy, including cognitive-behavioral therapy, biofeedback, and relaxation techniques, is particularly helpful for patients with coexisting anxiety or depression.

Medication Overuse Headache

• Patient education about the potential for overuse of analgesic medication to lead to headache progression is key. Include the use of over-the-counter analgesics in the discussion.
• The physician initiates a preventative medication while simultaneously assisting the patient in discontinuing the causative medication.
• Patients may experience withdrawal symptoms of nausea and anxiety for 2 to 10 days when the analgesic medication is discontinued.
• There is no consensus on the most appropriate medication for use as bridge therapy following discontinuation of the offending drug. Long-acting NSAIDs, prednisone, dihydroergotamine, and antiemetics are options.[24] The medication should not be from the same class as the offending medication.
• Medications that may be effective for prophylaxis include topiramate, amitryptiline, valproic acid, and beta-blockers. The choice of medication should be based upon comorbidities and the primary headache disorder.[25]

Chronic Autonomic Cephalgia

• Indomethacin is the drug of choice for paroxysmal hemicrania, hemicrania continua, primary stabbing headache, hypnic headache, and Valsalva-induced headaches (e.g., cough headache, exercise headache).
• Verapamil is the drug of choice for the prevention of chronic cluster headaches. Verapamil requires titration to become effective, and glucocorticoids or dihydroergotamine can be used for exacerbations.
• Chronic cluster headaches not responsive to pharmacologic therapy can be treated with a non-invasive vagus nerve stimulator or sphenopalatine ganglion microstimulator.[11]
• First-line prophylactic therapy for chronic SUNCT and SUNA is lamotrigine. Topiramate and gabapentin are alternatives.[26]

• Medication-overuse headache 
• Brain neoplasm 
• Chronic infections (e.g., CNS tuberculosis)
• Chronic sinusitis
• Cervical spine-related pain
• CNS vasculitis
• Temporomandibular joint pathologies
• Idiopathic intracranial hypertension
• Chronic hydrocephalus

The prognosis of chronic headaches is variable. Anxiety and mood disorders, elevated levels of stress, insufficient sleep, poor headache management, and low socioeconomic status are the primary prognostic characteristics. Patients with higher expectations for treatment display a better prognosis for decreased headache intensity and frequency. No specific age group has an improved response to treatment. Incidence at an older age generally correlates to less severe symptoms. Employed patients responded better to treatment than those patients on medical leave.[9] Exercise, prophylactic medication regimen compliance, and cessation of overused medications tend to lead to a favorable prognosis.[1]

• Mood disorders
• Decreased quality of life
• Suicide
• Unemployment
• Progressive neurological deficits
• Vision loss
• Seizures
• Drowsiness
• Medication adverse effects

Patients should be educated to become more aware of their headache symptoms and triggers. Interventions should be clearly explained to patients.  

The role of over-the-counter analgesics in medication overuse headache must be explained to patients. Patients with all types of primary headaches have the potential to overuse analgesics and should be counseled on the potential for frequent use of these medications to worsen the intensity and frequency of headaches.

A primary care physician manages the majority of chronic headaches. Non-responsive cases are usually referred to neurologists or headache specialists. These patients also need the services of a team that also include psychologist, nurse, pharmacist, and physical therapist. This interprofessional team approach helps to maximize treatment potential, foster a clear message about chronic headache treatment, improves patient education.[27]