Hypoglossal nerve stimulation therapy safe, effective for OSA

03 May 2024 bySaras Ramiya
Up to 83 percent of patients prescribed continuous positive airway pressure (CPAP) therapy showed less than 4 hours of nightlUp to 83 percent of patients prescribed continuous positive airway pressure (CPAP) therapy showed less than 4 hours of nightly use.

Hypoglossal nerve stimulation (HGNS) therapy focuses on improving upper airway muscle tone, thus filling a gap in current surgical treatment strategy for obstructive sleep apnea (OSA), said Associate Professor Dr Toh Song Tar, Head and Senior Consultant at the Department of ENT-HNS, Singapore General Hospital.

Patients opting for HGNS therapy undergo a surgery to implant an upper airway stimulation device comprising a stimulation lead to engage tongue-protrusion function, a sensing lead to observe ventilatory effort, and a neurostimulator to stimulate upper airway muscle. About 1 month after surgery, the treating physician uses a device to program the neurostimulator while the patient is given a remote to switch on the neurostimulator every night. The therapeutic effect of HGNS is observable at the palate and base of tongue, both of which open wider, even with mild stimulation, Toh said. He was speaking at the ENT Summit 2024 in Kuala Lumpur.

HGNS therapy is well established and effective as an alternative treatment for patients who either had difficulty accepting or adhering to continuous positive airway pressure (CPAP) therapy. The landmark Stimulation Therapy for Apnea Reduction (STAR) trial showed the median apnea-hypopnea index (AHI) score reduced by 68 percent—from 29.3 events/hour to 9.0 events/hour (P<0.001)—at 12 months after the surgical implant. The study’s 126 participants were mostly men (83 percent) with a mean age of 54.5 and mean body-mass index of 28.4 kg/m2. [N Engl J Med 2014;370:139–149]

The 5-year follow-up of the STAR trial showed that the AHI score was 6.2 events/hour while excessive daytime sleepiness based on the Epworth Sleepiness Scale (ESS) showed normalized scores. [Otolaryngol Head Neck Surg 2018;159(1):194–202] In contrast to CPAP, compliance for this device is quite high, said Toh. Self-reported nightly device use were 80 percent or above after 1 to 5 years.

The ADHERE Registry, which collates real-world data on AHI and ESS scores of patients on HGNS therapy, showed similar safety and efficacy. [J Clin Sleep Med 2022;18(6):1657–1665] The registry revealed less than 0.5 percent of implant procedures ended up in serious adverse events such as hematoma, infection, failed implant, and pneumothorax. Postoperative complications were reported in about 2 percent of patients and mostly involved revision of sensor and stimulation leads, said Toh.

The term OSA was created by the late Professor Dr Christian Guilleminault in 1972. OSA is characterized by repetitive upper airway obstruction, oxygen desaturation, arousals, and sleep fragmentation. The worldwide prevalence of OSA among adults aged 30 to 69 is estimated at 936 million for mild-to-severe OSA and 425 million for moderate-to-severe OSA. [Lancet Respir Med 2019;7(8):687–698] In Singapore, the prevalence of moderate-to-severe OSA is 30.5 percent. [Respirology 2016;21(5):943–950]

Untreated OSA can increase the risk of hypertension, type 2 diabetes, stroke, heart disease, traffic accidents, and premature mortality. [World J Otorhinolaryngol Head Neck Surg 2015;1(1):17–27, N Engl J Med 1999;340(11):847–851] Although CPAP therapy is the gold standard treatment for OSA, studies have shown that 29 percent to 83 percent of patients use CPAP therapy less than 4 hours/night limiting its effectiveness. [Proc Am Thorac Soc 2008;5(2):173–178]