Table 3.

Summary of reviewed case studies (k = 8)

Year	Author(s)	Study type	Case composition	Type of chronic pain	Type of trauma	Type of self-harm	Primary implications
2015	Kuppilli et al	Single-case	43-year-old woman with non-cancer somatic complaints of 19 years and opioid use of 13 years who presented to a public hospital in India for injection-related ulcers	Range of changing experience of pain, including in head, back, abdomen, and during urination and menstruation	Recent death of husband	Self-injection of pentazocine with resulting ulcers requiring surgery	Implies opiate use in response to chronic pain may produce chemical/psychological dependencies that give rise to self-damaging behavior in relation to further opiate acquisition and administration. Recent stressors, such as death of a loved one, may contribute to increased risk of such self-injurious behavior.
2012	Banke et al	Single-case	40-year-old white male bodybuilder presenting to an orthopedic clinic who self-injected sesame seed oil into 20 muscle areas for 8 years for “muscle augmentation and shaping”	Persistent pain particularly in both upper arms lasting at least 3 years after septic surgery to reduce infection and remove unhealthy material	“The general history was free of trauma”	Self-injection of sesame seed oil with resulting swelling, inflammation, and particularly cystic scarring and infection in right arm requiring surgery	Example of chronic pain that may be the direct result of repeated NSSI. In this case, self-injury was motivated by secondary benefit (i.e., body enhancement) rather than for direct benefit of self-injury itself (e.g., emotion regulation).
2011	Kachramanoglou et al	Single-case	17-year-old male adolescent who presented for rehabilitative treatment after a motor vehicle accident	Intermittent dull arm pain and sharp burning sensations in forearm lasting at least 14 months post-accident	Motor vehicle accident	Biting of nails and fingers of hand on injured arm resulting in irreversible loss of tissue and multiple hospitalizations	Highlights NSSI that may occur as a compulsive behavior directed towards body parts damaged in traumatic physical accident, possibly potentiated by history of related compulsive behavior (i.e., nail biting during adolescent years). Authors compare such behavior to autotomy seen in injured animals.
2009	Kapfhamer et al	Single-case	38-year-old woman who presented to ER after self-injection of canine intranasal vaccine	Chronic back pain	Domestic abuse	Self-injection of three vials of “reconstituted canine intranasal kennel cough vaccine” into right forearm to “end the pain”	Evidence that limited acute emotion regulation capacity in conjunction with prior history of mood disorder, suicide attempt, and other risk factors such as chronic pain and domestic abuse may give rise to self-harm in the context of acute stressors related to physical health and capacity (e.g., “frustrat[ion] about her physical condition while walking her dogs”). It is unclear if patient’s injection was suicidal or non-suicidal in nature.
2008	Frost et al	Case series	Five adult patients (two women) with traumatic spinal cord injury with established relationship with authors employed at a rehabilitative medicine clinic	Three of five patients reported persistent pain; only one reported pain in injured limb	Motor vehicle accident; diving accident; fall of unknown traumatic severity; injury of unknown traumatic severity; complication of cervical disk surgery	Autophagia of digits in hand associated with impaired functioning due to spinal cord injury	Suggests that NSSI may function to stimulate parts of the body that have lost sensation due to physical injury. Reports that all patients engaged in nail biting prior to spinal cord injury, suggesting that pre-existing compulsive behavior may exacerbate onset of NSSI post-injury.
1996	Mailis	Case series	Four adult patients with chronic pain seen by the author, the director of a physical medicine and rehabilitation hospital division	Wallenberg’s syndrome; post-cardotomy pain syndrome; brachial plexus/nerve injury pain; complex regional pain syndrome	One patient (case 4) experienced a motor vehicle accident	Biting, scratching, and/or rubbing with resulting damage to skin or body, focused on part of body associated with dysesthesia associated with chronic pain/injury	Highlights link between post-injury/chronic pain NSSI and dysesthesia in targeted part of the body, implying that disruption of normal sensation (whether with increased or decreased pain response) in affected part of the body may contribute to self-injury in this part of the body. Evidence was found of increasing SIB with increasing pain in 3 of 4 patients. Authors note that depression, difficulty tolerating frustration, and social isolation occurred in 3 of 4 cases and personality disorder in one. No patient exhibited nail-biting prior to pain onset.
1990	Procacci & Maresca	Case series	Two adult male patients presenting to a pain clinic with brachial plexus injuries	Allodynia (and hyperpathia) in affected limb and hand	Motor vehicle accident	Biting of nails and fingers	Patients reported biting their nails and fingers in the middle of the night, producing pain and waking themselves from sleep. This behavior was successfully interrupted by wearing gloves at night.
1989	Ballard	Single-case	23-year-old woman admitted to a general hospital after overdose on sedative medication	History of headaches since age 18 subsequent to a chronic “feeling of pressure” in patient’s head since age 15	Denied an explicit trauma history, though patient noted she “had been shown little affection by her parents” and “had never been happy even as a child”	Superficial cuts on arms and scratching face as adolescent and again at age 22 after return of headache/pressure four years after lumbar puncture regimen at age 18 successfully eliminated these symptoms and NSSI	Authors suggest that intracranial hypertension may be an undiagnosed contributor to NSSI as well as the experience of headache, though no causal link is clear as both tension/headache and NSSI appeared and disappeared concurrently in the patient. However, patient did report that NSSI alleviated head tension/pain.

Note. All studies include assessment or description of patient chronic pain, trauma (or lack thereof), and self-harm and utilize qualitative single-case or case series methodology. “Self-harm’ includes suicidal self-injury, while “NSSI” only includes non-suicidal self-injury. NSSI non-suicidal self-injury