Selective contributions of executive function ability to the P3.

The P3 component (P300, P3b) is considered to be an effective index of attention and categorization processes when elicited in a visual oddball task, specifically reflecting the selection of a rare target item among frequent non-targets. Researchers have proposed that target categorization is guided by representations of target features held in working memory (WM), thus guiding attention and categorization processes to distinguish targets from non-targets. Although WM is theorized to have visuospatial, verbal and executive function components, most studies do not investigate how these WM components contribute to the P3. This study uses an individual differences approach to determine whether correlations between WM capabilities and P3 amplitudes indicate a common underlying cognitive construct. Participants (n = 140) completed an 80/20 visual oddball task to elicit the P3 as well as independent visual working memory (VWM), spatial working memory (SPWM), and executive function (task switching (TS) and digit symbol substitution (DSS)) tests. Results indicated that measures of executive function, DSS and TS, but not VWM or SPWM ability, correlated with and predicted faster task response times and greater P3 amplitudes. RT and WM measures were not correlated with P3 fractional area latencies. These results support context updating theory. Executive function WM availability, whether as a property of the participant's processing system or based on task demands, plays a functional role in the P3 and an important role in efficient visual categorization and goal-directed learning.

An unusual cause of diaphragm pacer failure in congenital central hypoventilation syndrome.

Congenital central hypoventilation syndrome is a rare genetic disorder affecting ventilatory response to hypercapnia and/or hypoxemia. We describe a case of diaphragm pacing (DP) failure in a 38-year-old woman with congenital central hypoventilation syndrome who used DP as ventilatory support only during sleep for 24 years. Diagnostic evaluation began with examination of external DP equipment, but adjustment did not elicit adequate diaphragm contractions. Clinical evaluation and transtelephonic monitoring showed absent function of the right pacer and diminished function of the left pacer. The patient had surgical exploration of her internal DP components. The operation revealed that the right pacer receiver had significant circumferential calcium accumulation. After replacement of the receivers in subcutaneous pockets closer to the skin surface, robust diaphragm contractions bilaterally occurred with stimulation. This case suggests DP failure can result from development of calcification and increased distance from the skin surface to the receivers due to weight gain. CITATION: Kwon A, Lodge M, McComb JG, et al. An unusual cause of diaphragm pacer failure in congenital central hypoventilation syndrome. J Clin Sleep Med. 2022;18(3):949-952.

Resistance to Neuromuscular Blockade by Rocuronium in Surgical Patients with Spastic Cerebral Palsy.

Individuals with spastic cerebral palsy (CP) often exhibit altered sensitivities to neuromuscular blocking agents (NMBAs) used for surgical intubation. We assessed usage of the NMBA rocuronium in patients with spastic CP and evaluated potential modifiers of dosing including gross motor function classification system (GMFCS) level, birthweight, gestational age, and the use of anticonvulsant therapy. In a case-control study, surgical patients with spastic CP (n = 64) or with idiopathic or non-neuromuscular conditions (n = 73) were enrolled after informed consent/assent. Patient data, GMFCS level, anticonvulsant use, and rocuronium dosing for intubation and post-intubation neuromuscular blockade were obtained from medical records. Findings reveal participants with CP required more rocuronium per body weight for intubation than controls (1.00 ± 0.08 versus 0.64 ± 0.03 mg/kg; p < 0.0001). Dosing increased with GMFCS level (Spearman's rho = 0.323; p = 0.005), and participants with moderate to severe disability (GMFCS III-V) had elevated rocuronium with (1.21 ± 0.13 mg/kg) or without (0.86 ± 0.09 mg/kg) concurrent anticonvulsant therapy. Children born full-term or with birthweight >2.5 kg in the CP cohort required more rocuronium than preterm and low birthweight counterparts. Individuals with CP exhibited highly varied and significant resistance to neuromuscular blockade with rocuronium that was related to GMFCS and gestational age and weight at birth.