Table 2.

Classification of chronic secondary pain syndromes [3, 4].

Diagnostic entity	Subcategory	Syndromes
C. cancer-related pain	(i) C. cancer pain	C. visceral cancer pain, C. bone cancer pain, C. neuropathic cancer pain
	(ii) C. postcancer treatment pain	Postcancer medicine pain (painful chemo-induced polyneuropathy)
		Postradiotherapy pain (C. painful radiation-induced neuropathy)
C. postsurgical or posttraumatic pain	(i) C. postsurgical	CP after amputation, CP after spinal surgery, CP after thoracotomy, CP after breast surgery, CP after herniotomy, CP after hysterectomy, CP after arthroplasty
	(ii) C. posttraumatic pain	CP after burns injury, CP after peripheral nerve injury (i.e., CRPS Type 2), CP after spinal cord injury, CP after brain injury, CP after whiplash injury, CP after musculoskeletal injury
C. neuropathic pain	(i) C. peripheral neuropathic pain	Trigeminal neuralgia, chronic neuropathic pain after peripheral nerve injury, painful polyneuropathy, postherpetic neuralgia, painful radiculopathy (including chemo- or radio-induced)
	(ii) C. central neuropathic pain	CCNP associated with spinal cord injury, CCNP associated with brain injury, C central poststroke pain, CCNP associated with multiple sclerosis
C. secondary headache or orofacial pain		CH or COP attributed to trauma or injury to the head or neck (e.g., CP after whiplash injury), CH or COP attributed to cranial or cervical vascular disorder, CH or COP attributed to nonvascular intracranial disorder, CH attributed to a substance or its withdrawal, CH or COP attributed to infection, CH attributed to disorders of homoeostasis or their nonpharmacological treatment, CH or COP attributed to disorder of the cranium, neck, eyes, ears, sinuses, salivary glands, oral mucosa, C. dental pain (e.g., attributed to irreversible pulpitis, or attributed to symptomatic apical periodontitis), C. neuropathic orofacial pain (e.g., TN or other cranial neuralgias), CH or COP attributed to chronic secondary temporomandibular disorders (e.g., chronic secondary orofacial muscle pain)
C. secondary visceral pain	(i) CVP from persistent inflammation	Each one could be in the head or neck region, in the thoracic region, in the abdominal region, in the pelvic region
	(ii) CVP from vascular mechanism
	(iii) CVP from mechanical factors
C. secondary musculoskeletal pain	(i) CMSP from persistent inflammation	(i) Due to infection, due to crystal deposition, due to autoimmune and autoinflammatory disorders
	(ii) CMSP associated with structural changes	(ii) CMSP associated with osteoarthritis, CMSP associated with spondylosis, CP after musculoskeletal injury
	(iii) CMSP associated with a disease of the nervous system	(iii) CMSP associated with Parkinson's diseases, CMSP associated with multiple sclerosis, CMSP associated with peripheral neurologic disease

C.: chronic, CRPS: chronic regional pain syndrome, CP: chronic pain, CCNP: chronic central neuropathic pain, CH: chronic headache, COP: chronic orofacial pain, and CVP: chronic visceral pain, CMSP: chronic musculoskeletal pain. Underlined: conditions included in this review.