Study Characteristics
The 17 papers that met the inclusion criteria are shown in Table 1 together with their quality assessment. These included two randomised controlled trials (RCTs). Zhang(15) compared the outcomes of PNN (n = 32) against nasal corticosteroid and oral antihistamines (n = 31) and Hua et al(16) compared the outcomes of PNN alone against PNN with pharyngeal neurectomy where the former group was used as the control group. There were two case-control studies(17,18) – both comparing outcomes of turbinate reduction with and without PNN. The remaining thirteen(9,12-13, 19-28) were case series; 5 prospective and 8 retrospective. Ogi et al.(25) published a case series and undertook a case-control sub-analysis on complications by sending questionnaires to patients who underwent endoscopic sinus surgery (without PNN) as a control. Five studies(12,15,23-24,26) examined PNN as a single intervention with no concomitant nasal surgery. Eight studies(9,13,19-22,27-28) examined PNN with concurrent turbinate and septal surgery and four(17-18,21,25) examined PNN with concurrent turbinate reduction.
Two studies(9,17) specified that entire PNN was not undertaken and only posterior nasal nerve branches within the inferior turbinate or middle meatus were divided to improve symptoms. Kobayashi(21) retrospectively compared patients who underwent selective PNN to total PNN. The SPA was divided together with the posterior nasal nerve in four studies(15, 25, 26,28).
Sample sizes ranged from 8 to 1056 patients. The follow up period ranged from six months to eight years. Five studies(12,17,19-20, 22) cited a single post-operative review with no mention of timing, whereas Kanaya et al(12,22) did not specify their follow up at all.
Ten studies(9,13,15-18,21-22,25,27) recruited patients with allergic rhinitis only and three studies(19,20,28) included both allergic and non-allergic patients. The allergy status was not recorded in 4 studies(12,23-24,26). Allergic rhinitis was defined by IgE or RAST testing in six studies(17,18,19,20,25,28), skin prick testing in one study(27), and diagnosis was confirmed by both in two studies(9,13). The remaining studies did not define how allergic rhinitis was diagnosed in the study populations. Eleven studies(9,13,15-16,18-19,22-25,28) specified the treatments that had been used prior to PNN.