**4.1 Vascular and nonvascular intracranial pain disorders**

In this group, the differential diagnosis is essential since disorders like aneurysm, hemorrhage or hematoma, neoplasm, and edema can be life threatening and may require immediate care. The signs and symptoms include new or abrupt onset of pain, severe pain, and interruption of sleep by pain. In addition, non-pain symptoms may occur. Weight loss, ataxia, weakness, fever, changes in the neurologic examination, and neurologic deficits are common [37, 38, 49, 50].

### **4.2 Primary headache disorders**

Migraine and tension-type headache (TTH) are considered the most prevalent among primary headaches. TTH affects 60–80% of the population while migraine has a prevalence of 15% (male 7.6%, female 18.3%) [39, 51]. Cluster headache is not very common (0.1%) [40, 41, 52, 53]; however, it is often misdiagnosed and mismanaged [42, 54]. Despite be a secondary headache disorder medication-overuse headache (MOH), it often co-exists with primary headache disorders, and consequently they are described together.

#### **4.3 Intraoral pain disorders**

Dental and other oral diseases are very prevalent conditions in the general population. Pain complaints are the primary reason why most patients seek care from dental or medical doctors. Thus, regardless of intraoral pain is not exclusively a result of dental disorders, it is essential that all complaints of pain in the mouth and face are carefully studied in order to know if there is a dental problem in its origin. There are a lot of common somatic intraoral pain disorders, which can originate from disease involving one or more broad anatomic areas: the teeth, the surrounding soft tissues (mucosa and gingiva, tongue, salivary glands), and bone.

#### **4.4 Neuropathic pain disorders**

Neuropathic pain is defined as a symptom caused by a lesion or disease of the somatosensory system, including peripheral fibers (Aβ, Aδ, and C fibers) and central neurons. Its prevalence is about 7–10% among the general population. Different causes of neuropathic pain have been described. Undoubtedly, there is a connection between neuropathic pain and population ageing as well as the increase of survival of cancer treatment and systemic diseases as diabetes mellitus. Indeed, imbalances between excitatory and inhibitory somatosensory signaling, alterations in ion channels, and variability in the way that pain messages are modulated in the central nervous system have been implicated in neuropathic pain. The challenge of chronic neuropathic pain is linked to the complexness of neuropathic symptoms, poor outcomes, and consequently difficult treatment options. The importance of the medication and other medical treatment is directly connected with the quality of life in patients suffering from neuropathic pain. A multidisciplinary approach to the diagnosis and treatment of neuropathic pain is essential to achieve new and more efficient personalized intervention [43, 55].
