Pain and sensory function in neuronal ceroid lipofuscinosis

Abstract

Aims: In individuals with Neuronal Ceroid Lipofuscinosis (NCL; Batten disease), a rare neurodegenerative disorder, to explore 1) the pain experience, 2) the relationship between pain and self-injurious behavior (SIB), 3) the degree of sensory reactivity, and 4) the degree of sensory reactivity in comparison to individuals without NCL. Method: Following informed consent, eight participants with NCL (M age= 14.8 years, range=8-22) were characterized in terms of pain experience (frequency, type, intensity, interference, expression, and coping) and severity of SIB. A brief sensory test (light touch, repeated Von Frey monofilament) was conducted with each participant with NCL as well as with a sibling comparison group without NCL (n=8, M age= 23.5 years, range = 8-37). During sensory testing, pain expression was measured using the Battens Observational Pain Scale (BOPS) and infrared thermography (IRT) was used to quantify changes in skin/eye temperature. Results: Individuals with NCL experienced pain frequently and from multiple sources that most negatively impacted enjoyment of life, mood, sleep, and social interactions. Individuals with NCL were significantly more likely to express their pain using vocal/social pain behaviors rather than body and limbs (p<.05) or physiological behaviors (p<.01). When in pain, individuals tended to seek social support more often. Individuals with NCL who had moderately severe SIB showed significantly more pain behaviors than individuals with mild or no SIB (p<.05). Individuals with NCL were reactive to the sensory testing as IRT temperatures significantly increased (p<.001). Across combined conditions (light touch, repeated Von Frey), individuals with NCL were significantly more reactive (BOPS total score) to sensory testing compared to individuals in the sibling comparison group (p< .05). Similarly, IRT difference scores between sensory conditions revealed a significant increase in temperature at all face/eye sites for individuals with NCL compared to siblings (p<.001). Interpretation: In this sample of individuals with NCL pain was intense and frequent with multiple sources that interfered with a range of daily activities. Individuals with moderately severe SIB may be more sensitive to pain or may experience more pain in general. BOPS scores were elevated prior to sensory testing suggesting that individuals with NCL are living with ongoing pain. The increased pain expression during the repeated application of the Von Frey filament, a partial test of central sensitization, further suggests that the pathophysiology of the ongoing pain individuals with NCL are living with is likely centrally not peripherally mediated.