Self-injurious behavior and tuberous sclerosis complex: Frequency and possible associations in a population of 257 patients
Introduction
Self-injurious behavior (SIB) refers to behavior that results in physical injury to one’s own body [1], [2]. SIB is commonly seen in individuals with intellectual disabilities, including autism [3], mental retardation [4], Cornelia de Lange syndrome [5], Lesch–Nyhan disease [6], and Smith–Magenis syndrome [7]. Studies of intellectually disabled populations in community homes and hospitals have demonstrated that SIB is not uncommon, with a frequency of SIB/self-directed aggression of 17–24% [8], [9], [10]. However, SIB is often difficult to treat [11].
Studies provide evidence to support multiple possible etiologies for SIB. One theory is that SIB develops as a result of neurochemical abnormalities involving dopamine, serotonin, and/or endogenous opioids, and it may be further aggravated by lack of GABAergic inhibition. SIB may also serve a communicative role because of the lack of sufficient social skills and, in some cases, may be an expression of suffering from chronic health problems [2].
Tuberous sclerosis complex (TSC) is a genetic disorder characterized by the presence of hamartomas within multiple organ systems, including the brain, heart, skin, kidney, lungs, and eyes. TSC is caused by mutations in either of two tumor suppressor genes: TSC1 on chromosome 9 [12], and TSC2 on chromosome 16 [13]. The frequency of TSC is between 1 in 5800 and 1 in 10,000 [14], [15], [16]. Epilepsy is reported in up to 80 to 90% of individuals with TSC [17], [18], with onset usually occurring in childhood, often as infantile spasms [18]. Half of the people with TSC have cognitive impairment, and the other half have normal IQs [19]. Additional possible comorbid conditions include learning disabilites, sleep disorders, hyperactivity, attention deficit, aggressiveness, autism, mental retardation [20], anxiety, and depression.
The central nervous system lesion types seen in TSC include tubers, subependymal nodules (SENs), subependymal giant cell tumors (SGCTs), and white matter abnormalities. Tubers are hamartomas found primarily in the cerebral cortex and underlying white matter [20]. They are present in more than 80% of individuals with TSC and are thought to be related to clinical presentations of epilepsy, mental retardation, and autism. SENs are asymptomatic, whereas SGCTs can cause obstructive hydrocephalus [21].
In this study, we examined the frequency of SIB in a TSC population of 257 patients. We also examined possible associations with SIB, including locations of tubers and interictal spikes.
Section snippets
Methods
We performed a retrospective chart review of 257 patients with TSC (average age = 19 years, range = 5.8–53.2) seen at the Carol and James Herscot Center for Children and Adults with Tuberous Sclerosis Complex at Massachusetts General Hospital from January 2002 to September 2007. Patients were classified as self-injurious if they had any record of prior or current SIB documented in their charts. This included self-hitting, self-biting, aggressive hair pulling, and aggressive “picking at” or “pulling
Results
Of 257 patients with TSC, 26 were identified as having a history of SIB, giving a frequency of 10%. In an attempt to identify features specifically associated with SIB, we compared these 26 patients with a group of patients with TSC without psychiatric symptoms and with a group of patients with TSC with psychiatric symptoms other than SIB (see Table 1, Table 2, Table 3, Table 4).
Characteristics found to be significantly different between patients with TSC with SIB (TSC/SIB) and patients with
Discussion
We measured a high frequency of SIB in a TSC population referred to a tertiary care center. The 10% frequency of SIB in this population was consistent with previous studies of SIB in individuals with cognitive delays [8], [9], [10].
Significant differences were identified between patients with TSC/SIB and patients with TSC without psychiatric symptoms. Patients with TSC/SIB had a significantly higher frequency of history of seizures, MR, autism, interictal spike focus in the left frontal lobe,
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