A lumbar puncture is a procedure in which cerebral spinal fluid is removed from the spine with a needle. A lumbar puncture is necessary to look for infection or blood in the spinal fluid. A lumbar puncture can also evaluate the pressure in the spinal column, which can be useful for people with idiopathic intracranial hypertension (usually young, obese women who have increased intracranial pressure), or other causes of increased intracranial pressure. In most cases, a CT scan should be done first.

All people who present with red flags indicating a dangerous secondary headache should receive neuroimaging. The best form of neuroimaging for these headaches is controversial. Non-contrast computerized tomography (CT) scan is usually the first step in head imaging as it is readily available in Emergency Departments and hospitals and is cheaper than MRI. Non-contrast CT is best for identifying an acute head bleed. Magnetic Resonance Imaging (MRI) is best for brain tumors and problems in the posterior fossa, or back of the brain. MRI is more sensitive for identifying intracranial problems, however it can pick up brain abnormalities that are not relevant to the person's headaches.

The American College of Radiology recommends the following imaging tests for different specific situations:

Cluster headaches are often misdiagnosed, mismanaged, or undiagnosed for many years; they may be confused with migraine, "cluster-like" headache (or mimics), CH subtypes, other TACs ( trigeminal autonomic cephalalgias), or other types of primary or secondary headache syndrome. Cluster-like head pain may be diagnosed as secondary headache rather than cluster headache.

A detailed oral history aids practitioners in correct differential diagnosis, as there are no confirmatory tests for CH. A headache diary can be useful in tracking when and where pain occurs, how severe it is, and how long the pain lasts. A record of coping strategies used may help distinguish between headache type; data on frequency, severity and duration of headache attacks are a necessary tool for initial and correct differential diagnosis in headache conditions.

Correct diagnosis presents a challenge as the first CH attack may present where staff are not trained in the diagnosis of rare or complex chronic disease. Although experienced ER staff are sometimes trained to detect headache types, CH attacks themselves are not directly life-threatening, they are linked to an increased risk of suicide.

Individuals with CH typically experience diagnostic delay before correct diagnosis. People are often misdiagnosed due to reported neck, tooth, jaw, and sinus symptoms and may unnecessarily endure many years of referral to ear, nose and throat (ENT) specialists for investigation of sinuses; dentists for tooth assessment; chiropractors and manipulative therapists for treatment; or psychiatrists, psychologists and other medical disciplines before their headaches are correctly diagnosed. Under-recognition of CH by health care professionals is reflected in consistent findings in Europe and the United States that the average time to diagnosis is around seven years. Medical students receive little training in differential diagnoses and management of headaches.

Cluster headache may be misdiagnosed as migraine or sinusitis. Other types of headache are sometimes mistaken for, or may mimic closely, CH. Incorrect terms like "cluster migraine" confuse headache types, confound differential diagnosis and are often the cause of unnecessary diagnostic delay, ultimately delaying appropriate specialist treatment.

Headaches that may be confused with CH include:

- Chronic paroxysmal hemicrania (CPH) is a unilateral headache condition, without the male predominance usually seen in CH. Paroxysmal hemicrania may also be episodic but the episodes of pain seen in CPH are usually shorter than those seen with cluster headaches. CPH typically responds "absolutely" to treatment with the anti-inflammatory drug indomethacin where in most cases CH typically shows no positive indomethacin response, making "Indomethacin response" an important diagnostic tool for specialist practitioners seeking correct differential diagnosis between the conditions.

- Short-lasting unilateral neuralgiform headache with conjunctival injection and tearing (SUNCT) is a headache syndrome belonging to the group of TACs.

- Trigeminal neuralgia is a unilateral headache syndrome, or "cluster-like" headache.

Although the original Silberstein–Lipton criteria and the original description by Vanast make no suggestion for the exclusion of migrainous features in NDPH, the current ICHD criteria exclude patients with migrainous features. When migraine features are present, classification thus becomes problematic.

It has been reported that migraine symptoms may be present in over 50% of NDPH patients. The current criteria definition thus excludes more than half of patients with new onset of daily headache. This exclusion due to migrainous features could have adverse scientific, diagnostic, and treatment consequences.

One proposal for reclassification of the criteria is from a study conducted on retrospective analysis of the records of 1348 patients regularly treated at the headache clinic of the Department of Neurology of Santa Casa de São Paulo, Brazil, and would be the following subdivision: NDPH with migraine features and without migraine features that would allow the inclusion of all individuals present who has a daily and persistent headache from the beginning.

Another proposed reclassification of the criteria is from a study conducted as a retrospective chart review of patients seen at the Headache Center at Montefiore Medical Center in Bronx, New York, from September 2005 to April 2009. The revised criteria for NDPH definition does not exclude migraine features (NDPH-R), and three subdivisions were created and described based on prognosis: Persisting, remitting, and relapsing–remitting. Additionally, this revised criteria would not include parts C or D currently required by the ICHD diagnostic criteria for NDPH.

Most patients have persistent headaches, although about 15% will remit, and 8% will have a relapsing-remitting type. It is not infrequent for NDPH to be an intractable headache disorder that is unresponsive to standard headache therapies.

As of 2013 tension headaches affect about 1.6 billion people (20.8% of the population) and are more common in women than men (23% to 18% respectively). Despite its benign character, tension-type headache, especially in its chronic form, can impart significant disability on patients as well as burden on society at large.

Tension headaches that do not occur as a symptom of another condition may be painful, but are not harmful. It is usually possible to receive relief through treatment. Tension headaches that occur as a symptom of another condition are usually relieved when the underlying condition is treated. Frequent use of pain medications in patients with tension-type headache may lead to the development of medication overuse headache or rebound headache.

As diagnostic criteria have been indecisive and its pathophysiology remains unclear, no permanent cure is available. Antiepileptic medications (membrane-stabilizing drugs) such as pregabalin, gabapentin, topiramate, and lamotrigine improve symptoms, but there is no effective permanent or long-term treatment for SUNCT.

However, a few short-term treatments are available and can relieve and possibly prevent some symptoms of attacks.

Lamotrigine exhibits some long-term prevention and reduction in many patients; however, titration of dose is difficult due to adverse skin reactions.

Topiramate also has preventive effects but it is accompanied by a high risk of severe side-effects for patients with a history of kidney stones, glaucoma, depression, or low body weight.

Intravenous lidocaine can abolish symptoms during its administration, or reduce frequency and duration of attacks. However, administration of intravenous lidocaine requires careful monitoring of ECG and blood pressure.

Methylprednisolone therapy shows some promise in short-term prevention of attacks, even though its mechanism of action is yet to be discovered.

The calcium channel blocker verapamil is reported to be useful in alleviating symptoms (lower frequency and duration of attacks), even though some patients experience worsened symptoms.

Various medications that are often used in other headache syndromes such as nonsteroidal anti-inflammatory drugs, acetaminophen, tricyclic antidepressants, calcium channel antagonists do not relieve the symptoms of SUNCT.

There have been attempts to alter oxygen supply during attacks to alleviate the symptoms since some of the headaches are caused by decreased oxygen supply; however, elevated blood oxygen level did not affect the symptoms.

Researchers now focus on the administration of various combination of medications and therapies to treat symptoms of SUNCT.

Though outwardly similar to cluster headaches, chronic paroxysmal hemicrania is rather different, and the two headaches are not a subset of one or the other. Key differences include:

- Different gender distributions – CPH is more common in women than men, with opposite occurring with cluster headaches.

- CPH attacks occur more frequently, but are shorter.

- Individuals with CPH are far more responsive to indomethacin than individuals with cluster headaches.

- CPH attacks can be provoked by neck movement.

- In a study conducted by Sjaastad, heating a patient's body will cause the painful side of the forehead to sweat more in CPH patients, while there will be less sweating on that side for those suffering from cluster headaches.

A ten-patient study conducted by Pareja et al. found that all patients diagnosed with CPH were responsive to indomethacin and were able to completely control their symptoms. Doses of the drug ranged from 25 mg per day to 150 mg per day with a median dose of 75 mg per 24-hour period.

Almost all cases of CPH respond positively and effectively to indometacin, but as much as 25 percent of patients discontinued use of the drug due to adverse side effects, namely complications in the gastrointestinal tract.

According to a case study by Milanlioglu et al., 100mg of lamotrigine, an antiepileptic drug, administered twice daily alleviated all painful symptoms. No side effects were noted after two months of treatment. Dosage of lamotrigine was decreased to 50mg a day after the first two months, and no symptoms or side-effects were recorded after a three-month followup.

Use of topiramate has also been found to be an effective treatment for CPH, but cluster headache medications have been found to have little effect.

SUNCT must be properly distinguished from cluster headaches, since cluster headaches also occur several times per day with separate attacks, and share some common symptoms. However, cluster headaches usually last longer (up to three hours), occur less often (three to five attacks per day), and do not accompany cranial autonomic symptoms. IHS standard criteria for the diagnosis of SUNCT specifically includes pain in the trigeminal division of the face, especially in the orbital region, often with cranial autonomic symptoms which last for relatively short periods of time (from five seconds to several minutes) up to 100 times per day. SUNCT is a major subset of SUNA, which does not accompany cranial symptoms; complete separation between the two is inappropriate since SUNCT does not necessarily always accompany cranial autonomic signs. Exact statistical data is not available due to common mis-diagnosis, and setting up diagnostic criteria is important.

The International Headache Classification established by the International Headache Society criteria for diagnosing SUNCT for therapeutic purposes is:

Symptoms of SUNCT often lead to misdiagnosis as paroxysmal hemicrania, which is also categorized in the same group. Inefficiency of indomethacin usually indicates SUNCT over paroxysmal hemicrania.

Misdiagnosis and indecisive diagnosis in the past has made it difficult to obtain accurate statistics about SUNCT. Proper diagnosis will broaden data availability and facilitate discovery of new treatment options and useful statistics.

Hemicrania continua generally responds only to indomethacin 25–300 mg daily, which must be continued long term. Unfortunately, gastrointestinal side effects are a common problem with indomethacin, which may require additional acid-suppression therapy to control.

In patients who are unable to tolerate indomethacin, the use of celecoxib 400–800 mg per day (Celebrex) and rofecoxib 50 mg per day (Vioxx - no longer available) have both been shown to be effective and are likely to be associated with fewer GI side effects. There have also been reports of two patients who were successfully managed with topiramate 100–200 mg per day (Topamax) although side effects with this treatment can also prove problematic.

Greater Occipital Nerve [GON] block comprising 40 mg Depomedrone and 10mls of 1% Lignocaine injected into the affected nerve is effective, up to a period of approximately three months. Changing the 'cocktail' to include [for example] 10mls of .5% Marcaine and changing to 2% Lignocaine, whilst in theory should increase the longevity, renders the injection completely ineffective. See 4.2 Posology and method of administration [flocculation]

Occipital nerve stimulation may be highly effective when other treatments fail to relieve the intractable pain.

MOH is common and can be treated. The overused medications must be stopped for the patient's headache to resolve. Clinical data shows that the treatment of election is abrupt drugs withdrawal, followed by starting prophylactic therapy. However, the discontinuation of overused drugs usually leads to the worsening of headache and the appearance of drug withdrawal symptoms (that greatly depend on the previously overused drugs and typically last from two to ten days and that are relieved by the further intake of the overused medication), which might reinforce the continuation of overuse. Where physical dependence or a rebound effect such as rebound headache is possible, gradual reduction of medication may be necessary. It is important that the patient's physician be consulted before abruptly discontinuing certain medications as such a course of action has the potential to induce medically significant physical withdrawal symptoms. Abruptly discontinuing butalbital, for example, can actually induce seizures in some patients, although simple over the counter analgesics can safely be stopped by the patient without medical supervision. A long-acting analgesic/anti-inflammatory, such as naproxen (500 mg twice a day), can be used to ease headache during the withdrawal period. Two months after the completion of a medication withdrawal, patients suffering from MOH typically notice a marked reduction in headache frequency and intensity.

Drug withdrawal is performed very differently within and across countries. Most physicians prefer inpatients programmes, however effective drug withdrawal may also be achieved in an outpatient setting in uncomplicated MOH patients (i.e. subjects without important co-morbidities, not overusing opioids or ergotaminics and who are at their first detoxification attempt). In the absence of evidence-based indications, in MOH patients the choice of preventive agent should be based on the primary headache type (migraine or TTH), on the drug side-effect profile, on the presence of co-morbid and co-existent conditions, on patient’s preferences, and on previous therapeutic experiences.

Following an initial improvement of headache with the return to an episodic pattern, a relevant proportion (up to 45%) of patients relapse, reverting to the overuse of symptomatic drugs.

Predictors of the relapse, and that could influence treatment strategies, are considered the type of primary headache, from which MOH has evolved, and the type of drug abused (analgesics, and mostly combination of analgesics, but also drugs containing barbiturates or tranquillisers cause significantly higher relapse rates), while gender, age, duration of disease and previous intake of preventative treatment do not seem to predict relapse rate.

MOH is clearly a cause of disability and, if not adequately treated, it represents a condition of risk of possible co-morbidities associated to the excessive intake of drugs that are not devoid of side-effect. MOH can be treated through withdrawal of the overused drug(s) and by means of specific approaches that focus on the development of a close doctor-patient relationship in the post-withdrawal period.

Opioids and butalbital are sometimes inappropriately used as treatment for migraine and headache and should be avoided in favor of more effective, migraine-specific treatments. Opioid and butalbital use can worsen headaches and cause MOH. When a patient fails to respond to other treatment or migraine specific treatment is unavailable, then opioids may be used.

Regular use of over-the-counter drugs such as paracetamol and NSAIDs can also be a cause of MOH. OTC medication for headache should be limited to use for not more than two days weekly. Concurrent with MOH, overuse of acetaminophen (AKA paracetamol in some countries) for treating headaches risks causing liver damage and NSAID overuse can cause gastrointestinal bleeding.

The following diagnostic criteria are given for hemicrania continua:

1. Headache for more than 3 months fulfilling other 3 criteria:

2. All of the following characteristics:

- Unilateral pain without side-shift

- Daily and continuous, without pain-free periods

- Moderate intensity, but with exacerbations of severe pain

3. At least one of the following autonomic features occurs during exacerbations and ipsilateral to the side of pain:

- Conjunctival injection and/or lacrimation

- Nasal congestion and/or rhinorrhea

- Ptosis and/or miosis

4. Complete response to therapeutic doses of indomethacin, although cases of hemicrania continua that do not resolve with indomethacin treatment have been documented.

A variant on hemicrania continua has also been described, in which the attacks may shift sides, although meeting the above criteria in all other respects.

Main features differentiating CPH from cluster headaches (migrainous neuralgia, above) are the higher frequency and shorter duration of attacks, higher incidence in women, and the response to treatment with indomethacin. CPH is not associated with cranial nerve palsies.

The most common chronic treatment method is the use of medicine. Many people try to seek pain relief from analgesic medicines (commonly termed pain killers), such as aspirin, acetaminophen, aspirin compounds, ibuprofen, and opioids. The long term use of opioids; however, appears to result in greater harm than benefit. Also, abortive medications can be used to "stop a headache once it has begun"; such drugs include ergotamine (Cafergot), triptans (Imitrex), and prednisone (Deltasone). However, medical professionals advise that abuse of analgesics and abortive medications can actually lead to an increase in headaches. The painkiller medicines help headaches temporarily, but as the "quick fix" wears off, headaches become more re-current and grow in intensity. These "rebound headaches" can actually make the body less responsive to preventive medication. The conditions keep worsening if one takes paracetamol, aspirin and non-steroidal anti-inflammatory drugs (NSAIDs) for 15 days a month or more. Therefore, analgesic and abortive medications are often advised for headaches that are not chronic in nature.

Chronic headache, or chronic daily headache (CDH), is classified as experiencing fifteen or more days with a headache per month. It is estimated that chronic headaches affect "4% to 5% of the general population". Chronic headaches consist of different sub-groups, primarily categorized as chronic tension-type headaches and chronic migraine headaches. The treatments for chronic headache are vast and varied. Medicinal and non-medicinal methods exist to help patients cope with chronic headache, because chronic headaches cannot be cured. Whether pharmacological or not, treatment plans are often created on an individual basis. Multiple sources recommend "multimodal treatment", which is a combination of medicinal and non-medicinal remedies. Some treatments are controversial and are still being tested for effectiveness. Suggested treatments for chronic headaches include medication, physical therapy, acupuncture, relaxation training, and biofeedback. In addition, dietary alteration and behavioral therapy or psychological therapy are other possible treatments for chronic headaches.

Although specific complications of SLE may cause headache (such as cerebral venous sinus thrombosis or posterior reversible encephalopathy syndrome), it remains unclear whether specific investigations (such as lumbar puncture or magnetic resonance imaging, MRI) are needed in lupus patients presenting with headache. Although studies using MRI or single-photon emission computed tomography (SPECT) often find abnormalities, the value of these findings remains unclear, and they have not been able to distinguish a special "lupus headache" from other headache types in people with lupus.

The ICHD-2 lists diagnostic criteria for "persistent idiopathic facial pain" (the term that replaces AFP in this classification):

There are presently no accepted medical tests which consistently discriminate between facial pain syndromes or differentiate Atypical Facial Pain from other syndromes. However, a normal Radiograph, CT, and MRI may help to exclude other pathology such as arterio-veinous malformation, tumor, temporomandibular joint disorder, or MS.

Critics of this concept argue that there are no quality studies showing that headaches in patients with SLE differ from those in the general population. A detailed definition of the term lupus headache is lacking, since the terms "severe" and "persistent" are not quantified. Narcotic analgesics are not recommended for migraines or other common headache types. Other definitions from the IHS do not include responsiveness to treatments as a diagnostic criterion. Migraine patients are typically adult women around age 40, a demographic group in which SLE is also more common.

Hypnic headaches are benign primary headaches that affect the elderly, with the average age of onset being 63 ± 11 years. They are moderate, throbbing, bilateral or unilateral headaches that wake the sufferer from sleep once or multiple times a night. They typically begin a few hours after sleep begins and can last from 15–180 min. There is normally no nausea, photophobia, phonophobia or autonomic symptoms associated with the headache. They commonly occur at the same time every night possibly linking the headaches with circadian rhythm, but polysomnography has recently revealed that the onset of hypnic headaches may be associated with REM sleep.

Lithium carbonate 200–600 mg at bedtime is an effective treatment for most patients but for those that can not tolerate Lithium, Verapamil, indomethacin or methylsergilide may be tried. Two patients have also responded to flunarizine 5 mg. It has also been shown that 1–2 cups of coffee or 100–200 mg of caffeine before bed can prevent hypnic headaches.

For diagnosis of hypnic headache syndrome, headaches should occur at least 15 times per month for at least one month. Included in the differential diagnosis of a new onset nighttime headaches in the elderly is drug withdrawal, temporal arteritis, Sleep apnea, oxygen desaturated, Pheochromocytoma, intracranial causes, primary and secondary neoplasms, communicating hydrocephalus, subdural hematoma, vascular lesions, migraines, cluster headaches, chronic paroxysmal hemicrania and hypnic headache. All other causes must be ruled out before the diagnosis of hypnic headache can be made.

Research suggests that people with AFP are not helped greatly by health care professionals. One study reported that on average, individuals had consulted 7.5 different doctors. 91% had seen dentists, 80% physicians, 66% neurologists, 63% ear, nose and throat surgeons, 31% orthopedic and maxillofacial surgeons, 23% psychiatrists, 14% neurosurgeons and 6% ophalmologists and dermatologists. In this study, the individuals had been subjected to a wide variety of different treatments, from surgery, antidepressants, analgesics and physical therapies. None of the persons reported that surgery was beneficial, and in many cases the pain was worsened by surgery. The article sited as the source of this information was withdrawn from publication, saying the information was out of date and not meeting Cochrane methodological standards.

It has been suggested that the onset of chronic facial will likely be a life changing development for those affected.

Diagnosis starts by examining the patient's symptoms. Symptoms can vary. Symptoms can include headache, sensitivity to light, neck stiffness, nausea, and vomiting. In some patients, fever is absent. Neurological examination and MRI can be normal.

Mollaret's meningitis is suspected based on symptoms, and can be confirmed by HSV 1 or HSV 2 on PCR of Cerebrospinal fluid (CSF), although not all cases test positive on PCR. PCR is performed on spinal fluid or blood, however, the viruses do not need to enter the spinal fluid or blood to spread within the body: they can spread by moving through the axons and dendrites of the nerves.

During the first 24 h of the disease the spinal fluid will show predominant polymorphonuclear neutrophils and large cells that have been called endothelial (Mollaret’s) cells.

A study performed on patients who had diffuse symptoms, such as persistent or intermittent headaches, concluded that although PCR is a highly sensitive method for detection, it may not always be sensitive enough for identification of viral DNA in CSF, due to the fact that viral shedding from latent infection may be very low. The concentration of viruses in CSF during subclinical infection might be very low.

Investigations include blood tests (electrolytes, liver and kidney function, inflammatory markers and a complete blood count) and usually X-ray examination of the chest. The most important test in identifying or ruling out meningitis is analysis of the cerebrospinal fluid (fluid that envelops the brain and the spinal cord) through lumbar puncture (LP). However, if the patient is at risk for a cerebral mass lesion or elevated intracranial pressure (recent head injury, a known immune system problem, localizing neurological signs, or evidence on examination of a raised ICP), a lumbar puncture may be contraindicated because of the possibility of fatal brain herniation. In such cases, a CT or MRI scan is generally performed prior to the lumbar puncture to exclude this possibility. Otherwise, the CT or MRI should be performed after the LP, with MRI preferred over CT due to its superiority in demonstrating areas of cerebral edema, ischemia, and meningeal inflammation.

During the lumbar puncture procedure, the opening pressure is measured. A pressure of over 180 mm HO is suggestive of bacterial meningitis.

It is likely that Mollaret meningitis is underrecognized by physicians, and improved recognition may limit unwarranted antibiotic use and shorten or eliminate unnecessary hospital admission.

PCR testing has advanced the state of the art in research, but PCR can be negative in individuals with Mollaret's, even during episodes with severe symptoms. For example, Kojima et al. published a case study for an individual who was hospitalized repeatedly, and who had clinical symptoms including genital herpes lesions. However, the patient was sometimes negative for HSV-2 by PCR, even though his meningitis symptoms were severe. Treatment with acyclovir was successful, indicating that a herpes virus was the cause of his symptoms.

The clinician should first rule out conditions with similar symptoms, such as subarachnoid hemorrhage, ischemic stroke, pituitary apoplexy, cerebral artery dissection, meningitis, and spontaneous cerebrospinal fluid leak. This may involve a CT scan, lumbar puncture, MRI, and other tests. Posterior reversible encephalopathy syndrome has a similar presentation, and is found in 10–38% of RCVS patients.

RCVS is diagnosed by detecting diffuse reversible cerebral vasoconstriction. Catheter angiography is ideal, but computed tomography angiography and magnetic resonance angiography can identify about 70% of cases. Multiple angiographies may be necessary. Because other diseases (such as atherosclerosis) have similar angiographic presentations, it can only be conclusively diagnosed if vasoconstriction resolves within 12 weeks.