Headache is the symptom of pain in the face, head, or neck. It can occur as a migraine, tension-type headache, or cluster headache. There is an increased risk of depression in those with severe headaches.Headaches can occur as a result of many conditions. There are a number of different classification systems for headaches. The most well-recognized is that of the International Headache Society, which classifies it into more than 150 types of primary and secondary headaches. Causes of headaches may include dehydration; fatigue; sleep deprivation; stress; the effects of medications (overuse) and recreational drugs, including withdrawal; viral infections; loud noises; head injury; rapid ingestion of a very cold food or beverage; and dental or sinus issues (such as sinusitis).Treatment of a headache depends on the underlying cause, but commonly involves pain medication (especially in case of migraine or cluster headache). A headache is one of the most commonly experienced of all physical discomforts.About half of adults have a headache in a given year. Tension headaches are the most common, affecting about 1.6 billion people (21.8% of the population) followed by migraine headaches which affect about 848 million (11.7%). Causes
There are more than 200 types of headaches. Some are harmless and some are life-threatening. The description of the headache and findings on neurological examination, determine whether additional tests are needed and what treatment is best.Headaches are broadly classified as "primary" or "secondary". Primary headaches are benign, recurrent headaches not caused by underlying disease or structural problems. For example, migraine is a type of primary headache.
Expanding over subdivision in depth of the clefts for every classification is not necessary because the principles of treatment and technique for correction are the same.There are four categories:

simple constriction rings
constriction rings associated with deformity of the distal part with or without lymphedema
constriction rings associated with acrosyndactyly
uterine amputationPatterson divided the constriction ring associated with acrosyndactyly into three types:

Type I: conjoined fingertips with well-formed webs of the proper depth
Type II: the tips of the digits are joined, but web formation is not complete
Type III: joined tips, sinus tracts between digits and absent websPatterson IThere are simple constriction rings which are strands most commonly around the distal extremities as fingers and toes. In general, the thumb is not likely to be affected by a constriction ring because the fetus typically holds the thumb in tight adduction flexion, making entanglement with strands less likely. These malformations need to be surgically removed which must be executed in different stages and can done by different techniques (see also treatment). Patterson IIThe CRS involves strands which obstruct the lymphatic vessels and thus causing fluid retention, distal of the affected extremity. This utters itself with swollen parts distal of the constriction. Patterson IIIIn this form there is a complex form of syndactyly named acrosyndactyly, the fingers (or toes) were initially separated but due to the constriction they are formed back together. Sometimes multiple fingers can be involved. The distal fusion between digits or toes never initially involves a skeletal coalition. The digits are usually hypoplastic if multiple digits are involved.