Chronic rhinitis affects up to an estimated 30% of the US population alone. Marked by symptoms of nasal congestion, rhinorrhea, postnasal drip, sneezing, and itching, chronic rhinitis can have a significant negative impact on quality of life. While the precise pathophysiology is not yet fully understood, chronic rhinitis has many potential causes, including allergy, environmental triggers, hormone induced, and autonomic dysregulation.

The posterior nasal nerve (PNN) has been implicated as an important mediator of the pathophysiology of chronic rhinitis. ^, As a peripheral branch of the vidian nerve, the PNN supplies the dominant source of autonomic innervation to the nasal mucosa, carrying the preganglionic parasympathetic branches of the greater superficial petrosal nerve and the postganglionic sympathetic fibers from the deep petrosal nerve. From the pterygopalatine fossa, the PNN enters the nasal cavity from the sphenopalatine foramen, and branches along the medial pterygoid plate to innervate the inferior, middle, and superior turbinates and meati. Overactive parasympathetic tone of the PNN results in excessive mucus production from the nasal mucosal lining. The region of the PNN is highlighted in Fig. 20.1 .

The posterior nasal nerve enters the nasal cavity in the region of the sphenopalatine foramen ( rectangle ), which is located at the posterior insertion of the basal lamella of the middle turbinate.

With an increasing understanding of PNN function and its favorable accessibility via nasal endoscopy, the PNN has been the target of several emerging office-based treatments for chronic rhinitis. The two most commonly used technologies include cryoablation (ClariFix, Stryker Corporation, Kalamazoo, MI; Food and Drug Administration [FDA] cleared in 2017) and radiofrequency neurolysis (RhinAer, Aerin Medical Inc., Mountain View, CA; FDA cleared in 2022). The ClariFix uses a nitrous oxide delivery through a cryoprobe to freeze and ablate the PNN, while preserving vascular supply to minimize surrounding soft tissue injury. RhinAer applies temperature-controlled radiofrequency energy to disrupt the PNN with minimal thermal damage to the surrounding connective tissue. More recently, the Neuromark system (Neurent Medical, Galway, Ireland; FDA cleared in 2021) has entered the market as another radiofrequency-based treatment that delivers multipoint radiofrequency energy for PNN disruption. The emergence of these devices offers patients alternative options to treatments for chronic rhinitis that require general anesthesia, such as posterior nasal neurectomy or vidian neurectomy, with added potential benefits of minimal recovery time and decreased cost.

Targeted treatments of the PNN are indicated for adult patients with moderate to severe symptoms of allergic rhinitis, nonallergic rhinitis, or mixed rhinitis. Targeted ablation techniques offer an alternative treatment option for patients who are unresponsive to or intolerant of medical treatments, representing an estimated 10% to 20% of the rhinitis population. Patients being considered for in-office PNN ablation should be able to tolerate awake nasal endoscopy with relative comfort.

In general, patients with obstructive anatomy (i.e., severe septal deviation obstructing the middle meatus) or pathology (i.e., nasal polyposis) are not good candidates for in-office treatments of the PNN. Absolute contraindications for cryoablation include cryoglobulinemia, paroxysmal cold hemoglobinuria, cold urticaria, Raynaud disease, or an infection near the target tissue. Other relative contraindications include cold sensitivity, neuropathic disorders, or bleeding disorders. Contraindications listed for radiofrequency neurolysis include nasal surgery within the past 3 months, medical conditions that impair the normal healing process, or a history of nasal injury.

Clinics performing targeted treatments of the PNN should be equipped with the standard capabilities for rigid nasal endoscopic procedures. PNN treatments can be performed using either a 0- or 30-degree endoscope. Patients should be seated comfortably in an upright position, with good support of the head. From 20 to 30 total minutes should be allotted, taking into account administration of anesthesia, nasal endoscopy and procedure, and an appropriate period of postprocedure observation. Hemodynamic monitoring is an option that can be considered for patients, particularly those with advanced age or a significant comorbidity profile.

The nasal cavity is decongested with topical medication such as oxymetazoline or phenylephrine. For local anesthesia, clinicians can use a topical anesthetic (i.e., 4% tetracaine or 3% bupivacaine) via aerosolized spray or a medication-soaked pledget. Topical decongestant/anesthetic medication can be administered under endoscopic visualization for more targeted delivery to the middle meatus. Additional local anesthesia can also be achieved with submucosal injection of 1% lidocaine with 1:100,000 epinephrine in the region of the sphenopalatine foramen, located at the posterior attachment of the middle turbinate basal lamella. For cryoablation, consideration can also be given to a 600-mg dose of oral gabapentin 1 hour before the procedure, which has been shown to significantly reduce both immediate and delayed discomfort.

The ClariFix is a handheld, single-use device that contains a cryoprobe on an angled arm. A cartridge of nitrous oxide is loaded onto the device. Under endoscopic visualization, the cryoprobe tip is advanced into the middle meatus in the region of the PNN, located at the posterior insertion of the basal lamella of the middle turbinate ( Fig. 20.2A ). The cryoprobe should be positioned to maintain contact with the mucosal surface as broadly as possible. The cryoprobe surface reaches–60°C to–80°C, achieving an estimated temperature of–20°C at a depth of 3 mm.

Cryoprobe placement (A) and deployment (B) within the middle meatus over the region of the posterior nasal nerve, located at the posterior attachment of the basal lamella (BL) of the middle turbinate (MT). EB , ethmoid bulla; IT , inferior turbinate; LNW , lateral nasal wall.

The cryoprobe is then deployed, triggering freezing temperature along the surface of the expanding balloon ( Fig. 20.2B ). Total time of cryoprobe activation is 30 to 60 seconds, with an option to divide 60 seconds into two 30-second treatments. When the treatment time is completed, the cryoprobe is then deactivated. Before removal of the cryoprobe, the patient should be asked to nasally breathe, which brings humidified, warm air into the field, defrosting the probe and allowing for an atraumatic detachment from the mucosal surface. The treated surfaces will have a blanched appearance. Following treatment, patients are observed in the clinic for several minutes to monitor for any adverse effects.

Bilateral treatment of the PNN is generally indicated for chronic rhinitis, though unilaterality of treatment can be tailored to the patient’s clinical history. Additional cryoablation treatment of PNN branches within the inferior meatus can also be considered by placing the cryoprobe under the posterior aspect of the inferior turbinate. Though cryoablative treatment of the inferior meatus is off-label use, preliminary data demonstrate feasibility and efficacy of this technique.

The RhinAer is similarly a handheld device that derives energy from a portable console. This device has an electrode-surfaced tip for radiofrequency energy delivery on the end of a malleable stylus. The tip is first dipped in a conducting gel and then placed in the posterior middle meatus with the electrode surface pushed gently into mucosa, laterally over the region of the sphenopalatine foramen ( Fig. 20.3A ). The device is then activated with a foot pedal, delivering temperature-controlled radiofrequency energy into the mucosa over the PNN. The treatment tip reaches approximately 60°C. The device can be repositioned multiple times to target a broader surface over the PNN and continues to include the posterior aspect of the inferior turbinate ( Fig. 20.3B ). Care should be taken to avoid overlapping regions of treatment. The device is then removed, and the patient is observed for adverse effects.

Radiofrequency neurolysis of the posterior nasal nerve with the RhinAer. The electrode tip is placed over the posterior nasal nerve branches at the sphenopalatine foramen (A) and the posterior aspect of the inferior turbinate (B). IT , inferior turbinate; MT , middle turbinate; S , septum.

The NeuroMark is a radiofrequency ablation device that is designed to deliver treatment in an impedance-controlled fashion at multiple points, with the goal to address anatomical variations in the PNN. This device has both proximal and distal leaflets that conform to patient anatomy and delivers energy at up to 20 sites intended to cover additional PNN branches of the lateral wall both anterior and posterior to the middle turbinate ( Fig. 20.4 ). During use, the device is oriented to laterality of the nasal cavity so that energy is not delivered through the medial electrodes that may be in contact with the septum.

Radiofrequency ablation of posterior nasal nerve branches with the NeuroMark device. The device has two sets of leaflets that deliver energy: an anterior set of leaflets (A) that contact the middle meatus and sphenopalatine foramen, and a posterior set of leaflets (B) that contact the medial pterygoid region posterior to the middle turbinate. MT , middle turbinate; S , septum.

In the 2017 pilot study of the ClariFix in 27 patients, there was a significant improvement demonstrated from a baseline rTNSS of 6.2 ± 0.5 to all post-treatment time points: 7 days (4.3 ± 0.4, n = 27, P < 0.005), 30 days (2.6 ± 0.3, n = 27, P < 0.001), 90 days (2.7 ± 0.4, n = 27, P < 0.001), 180 days (2.3 ± 0.5, n = 21, P < 0.001), and 365 days (1.9 ± 0.3, n = 15, P < 0.001). The allergic and nonallergic cohorts demonstrated similar benefit with treatment. Within the TNSS questionnaire, the largest reductions were seen in symptoms of rhinorrhea and congestion.

These findings have been corroborated with several larger-scale single-arm studies. ^{, , ,} The study with the largest cohort (N = 98) demonstrated a similar magnitude of improvement in rTNSS from baseline (6.1 ± 0.4) to 9 months (3.0 ± 2.4, P < 0.001), as well as significant improvements in RQLQ. In this study, 78.4% patients achieved the MCID in rTNSS. A long-term follow-up study of this same cohort showed that benefits in both rTNSS and RQLQ scores were sustained at 12 months and 24 months, with greater than 80% achieving MCID at all follow-up time points.

The highest level of evidence for PNN cryoablation is from a randomized, sham-controlled, patient-blinded study of 127 patients (64 treatment vs. 63 sham). The treatment arm demonstrated superior improvements in rTNSS score compared to the sham arm at 30 days (Δ–3.2 treatment vs. Δ–2.5 sham, P < 0.001) and 90 days (Δ–3.7 treatment vs. Δ–1.8 sham, P < 0.001). Significant improvement was also seen in RQLQ and NOSE scores at both time points. The percentage of patients achieving MCID in rTNSS was significantly higher in the treatment arm compared to the sham arm (73.4% vs. 38.5%, P < 0.001). A multivariate analysis model demonstrated that active treatment over sham was the only factor associated with significant improvement in rTNSS (odds ratio [OR] 3.430, 95% confidence interval [CI] 1.827–6.438), while other factors such as age, sex, rhinitis type, baseline rTNSS, or responsiveness to ipratropium bromide were not predictive of successful cryoablation treatment. A separate retrospective study looking specifically at predictors of improvement in rhinorrhea using the “runny nose” item from the Sinonasal Outcome Test-22 (SNOT-22) found that responsiveness to ipratroprium was a significant predictor of successful cryoablation treatment, with ipratropium responders showing a significant higher success rate compared to ipratropium nonresponders (84.9% vs. 33.3%, P < 0.001). This differential in treatment success based on ipratropium responsiveness may guide preprocedural counseling of patients when discussing expectations.

A summary of studies is shown in Table 20.1 , adapted from a systematic review and meta-analysis of 247 patients across five studies undergoing PNN cryoablation. This meta-analysis found significant improvements in pooled rTNSS from baseline to post-treatment at 1 month (Δ–3.48, 95% CI–3.73 to–3.23) and 3 months (Δ–3.50, 95% CI–3.71 to–3.29) and pooled RQLQ at 3 months (Δ–1.53, 95% CI–1.74 to–1.31). Potential limitations to the existing data include the majority of studies being supported by industry, as well as the low number of randomized controlled studies. Yet, taken together, the existing studies support the efficacy of the treatment of chronic rhinitis with cryoablation.

Table 20.1

Summary of Studies for Cryoablation of the Posterior Nasal Nerve

Author	Hwang et al.	Chang et al.	Yen et al.	Gerka Stuyt et al.	Del Signore et al.
General Data
Treatment group size	27	98	30	24	68
Country	United States	United States	United States	United States	United States
Age (y ± STD)	53.3 ± 3.3	58.6 ± 16.2	60.0 ± 15.8	60.0 ± 16.7	52.3 ± 15.8
Sex (female), n	17 (63%)	63 (64.3%)	16 (53.3%)	12 (50%)	45 (66.2%)
Race, n
White	—	89 (91.8%)	27 (90%)	—	61 (89.7%)
Black	—	2 (2.1%)	—	—	3 (4.4%)
Asian	—	2 (2.1%)	—	—	2 (2.9%)
Other	—	4 (4.1%)	—	—	2 (3.0%)
Ethnicity, n
Hispanic/Latino	—	2 (2.1%)	2 (6.7%)	—	5 (7.4%)
Other	—	94 (97.9%)	28 (93.3%)	—	63 (92.6%)
Patient Distribution, n
Allergic rhinitis	13 (48.1%)	28 (28.6%)	11 (39.3%)	3 (12.5%)	29 (42.6%)
Nonallergic rhinitis	13 (48.1%)	70 (71.4%)	17 (60.7%)	16 (66.7%)	39 (57.4%)
Mixed rhinitis	—	—	—	5 (20.8%)	—
Follow-Up Time Points
1 mo	Yes	Yes	Yes	Yes	Yes
3 mo	Yes	Yes	Yes	Yes	Yes
6 mo	Yes	Yes	No	No	No
9 mo	No	Yes	No	No	No
12 mo	Yes	No	No	Yes	No
Level of evidence (I–V)	IV	IV	IV	IV	II
rTNSS
Baseline rTNSS	6.2 ± 0.5	6.1 ± 1.9	7 ± 3.1	6.9 ± 2.8	8.1 ± 1.7
1 mo rTNSS	2.6 ± 0.3	2.9 ± 1.9	3.8 ± 3.1	3.2 ± 2.4	4.8 ± 2.3
3 mo rTNSS	2.7 ± 0.4	3 ± 2.3	3.2 ± 2.3	2.9 ± 1.4	4.3 ± 2.4
6 mo rTNSS	2.3 ± 0.5	3 ± 2.1	—	—	—
9 mo rTNSS	—	3 ± 2.4	—	—	—
12 mo rTNSS	1.9 ± 0.3	—	—	3.1 ± 2.6	—
RQLQ Scores
Baseline RQLQ score	—	3.0 ± 1.0	2.8 ± 1.1	—	2.7 ± 1.1
1 mo RQLQ score	—	—	—	—	1.3 ± 0.9
3 mo RQLQ score	—	1.5 ± 1.2	1.1 ± 1.2	—	1.2 ± 0.9
NOSE Scores
Baseline NOSE score	—	—	56.9 ± 28.1	—	53.8 ± 27.1
1 mo NOSE score	—	—	—	—	33.8 ± 26.9
3 mo NOSE score	—	—	25.5 ± 24.5	—	23.6 ± 22.3
VAS Scores
Baseline VAS score	—	—	75.9 ± 21.4	—	—
3 mo VAS score	—	—	36.0 ± 29.2	—	—
SNOT-22 Scores
Baseline SNOT-22 score	—	—	45.6 ± 19.9	—	—
3 mo SNOT-22 score	—	—	21.4 ± 16.4	—	—

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