Interventional Nerve Procedures for Pain Related to Head-and-Neck Cancer: A Systematic Review

Anaesthetic nerve block

Of the total 302 patients, 204 underwent sphenopalatine ganglion block (SPGB), with data derived from four studies.^[14-17] All procedures were performed through the transnasal approach. The main distinction was the setting in which it was administered: Two studies – Lamba et al.,^[14] a prospective cross-sectional study, and Pena et al.^[15] a case series, performed the SPGB in a clinical setting, directly administered by a physician. In contrast, the other two studies – Sanghavi et al. ^[16] a prospective observational study, and Saade and Paige,^[17] a case report – adopted a home-based model, in which the procedure was performed by a caregiver who had received appropriate medical training and supervision. In terms of outcomes, all studies reported significant pain reduction. Lamba et al.^[14] reported pain reduction from 7.42 ± 2.02 to 3.45 ± 1.21 and a decrease in morphine use after three sessions. Pena et al.^[15] observed pain relief ranging from 38% to 80%, lasting 2–35 days (mean ≈23 days). Sanghavi et al.^[16] showed pain reduction from 8.56 to 2.46, with relief lasting about 5 days, often requiring weekly repetition. Saade and Paige^[17] reported ≥50% pain relief with home-based SPGB using 4% lidocaine. Adverse effects were mild and self-limited: Giddiness (7 cases), runny nose (8 cases), transient throat numbness with swallowing difficulty (3 cases) and mild nasal bleeding (1 case). No serious complications were reported.

Glossopharyngeal nerve block (GNB) was evaluated in three studies, totalling 59 patients. In the randomised trial by Singh et al.,^[18] intraoral and extraoral approaches were compared. Both techniques were effective, but the intraoral approach showed better pain control during the first 2 months. The extraoral route, however, was technically easier, with fewer failed attempts and a shorter procedure time. The study by Yadav et al.,^[19] involving eight patients demonstrated sustained pain relief for up to 4 weeks after a single ultrasound-guided block. Similarly, the case report by Sirohiya et al.^[20] described complete pain resolution that persisted for 2 months following the intervention. Adverse effects were minimal: Singh et al.^[18]reported transient complications in 5 patients in the intraoral group (e.g. pain during injection, minor dysphagia), while no complications were observed in the other two studies.

Stellate ganglion block was assessed in two case series,^[21,22] including eight patients with pain related to HNC. Both studies reported significant pain relief, with effects lasting up to 3–4 weeks in one study and up to 12 weeks in the other. Improvements were also noted in the quality of life and patient satisfaction. No adverse effects or complications were reported in either study.

Finally, the last study assessed anaesthetic nerve blocks and evaluated different targets. Nasir et al.^[23] included 27 patients with cancer-related neuropathic pain and reported ≥75% pain relief in 82% of cases (mean duration 6.1 weeks).

Neurolysis

Among the included studies reporting neurolytic procedures, there was notable variation in terms of access route and guidance technique. Most glossopharyngeal nerve neurolyses were performed through a percutaneous lateral approach, often targeting the jugular foramen and guided by radiographic imaging (Bensignor et al.,^[24] Bajaj et al.,^[25] Montgomery and Cousins^[26]). One case report described the use of ultrasound for glossopharyngeal neurolysis (Bedder and Lindsay)^[27]. For the sphenopalatine ganglion, neurolysis was performed either through a transnasal approach (Varghese and Koshy)^[28] or through a lateral infratemporal route under fluoroscopy (Usman et al).^[29] In the remaining studies, including those by Khawaja and Scrivani^[31] and Kohase et al.,^[32] landmark-guided techniques were employed for more superficial peripheral nerves, such as the occipital, auriculotemporal and mandibular nerves.

GNB was one of the most frequently evaluated interventions, with four studies including 16 patients. The block was performed percutaneously at the jugular foramen under X-ray guidance. Two case series (Bensignor et al.,^[24] Bajaj et al.^[25]) and two case reports (Montgomery and Cousins,^[26] Bedder and Lindsay^[27]) reported significant short-term pain relief, lasting from 2 days to 2 weeks. Most studies reported no major complications, except for Montgomery and Cousins,^[26] who noted transient tongue weakness and hoarseness (1 case). Bensignor et al.^[24] discontinued the intervention early due to potential safety concerns.

Two studies^[28,29] evaluated sphenopalatine ganglion neurolysis in 23 patients. Varghese and Koshy^[28] used a transnasal approach with 0.5 mL of 6% phenol and reported immediate relief in most cases, with 8 maintaining it at 1 month. Usman et al.^[29] applied the block through an infratemporal approach in one patient, who remained pain-free and off medications after 1 month. Both studies reported that there are minimal or no complications.

In addition, Varghese et al.^[30] also reported a case report in which there was significant pain relief until the patient’s death, albeit prematurely, 1 week after discharge, and even improved his sleep, as he was unable to rest due to the intensity of the pain.

Two additional studies^[31,32] explored other nerve blocks beyond the most frequently assessed targets. Khawaja and Scrivani,^[31] in a retrospective study with 33 patients, reported that blocking the nerves involved in the painful region provided ≥75% pain relief in 72.7% of cases, with a mean pain reduction of 89.3% lasting approximately 9 weeks. Kohase et al.^[32] described a case report in which a mandibular nerve block achieved long-lasting pain control and prevented the need for increased opioid use. Adverse effects were mild, including burning pain in two patients and a small (<5 mm) injection-site ulcer in one, all resolving without complications.

Radiofrequency intervention-pulsed or thermal

Three studies^[33-35] involving a total of 53 patients employed thermal radiofrequency (TRF) for ablation of trigeminal nerve branches. The procedural parameters varied slightly across studies, with temperatures ranging from 60°C to 75°C, typically applied in 1-min cycles. Frank et al.,^[33] a retrospective study, reported immediate pain relief in 71% of patients. However, 7 patients experienced early recurrence and required reintervention. Among those who followed up, 49% remained pain-free for an average of 7 months. Two case reports by Silva-Ortiz and Plancarte-Sanchez^[34] and Mendelsohn et al.^[35] also described significant pain reduction, with the former reporting sustained relief for up to 6 months. Adverse effects reported by these studies were mild and included painful anaesthesia (2 patients), mild keratitis (3) and hypoesthesia in V2/V3 territory (1 case); no major complications were reported.

Two additional case series studies,^[36,37] totalling 10 patients, used TRF combining ablation of the glossopharyngeal and trigeminal nerves. Salar et al.^[36] reported improvement in pain episodes, mastication and swallowing. Giorgi and Broggi^[37] described pain control lasting from several months to 1 year. Reported complications were generally mild and included transient swallowing or phonation difficulties (6 cases), sensory loss (10 cases) and mild bradycardia (2 cases). One case of persistent dysphagia was noted.

Four studies^[38-41] evaluated radiofrequency ablation – either thermal or pulsed – applied exclusively to the glossopharyngeal nerve, totalling 101 patients. Benyameen et al.,^[38] a randomised clinical trial, divided patients into two groups receiving PRF with voltages of 65–75 V (super-voltage) and 45 V (standard voltage). Both groups experienced pain reduction and decreased opioid use; however, the super-voltage PRF group showed greater efficacy, with a statistically significant difference observed only at the 3^rd week of follow-up. Bharti et al.,^[39] a prospective interventional study using PRF, reported pain improvement in 92% of patients, with pain control lasting up to 7.8 months. Pagura et al.,^[40] a retrospective study, evaluated TRF and observed complete pain relief in 11 of 15 patients and partial relief in the remaining 4. In the case report by Khan et al.,^[41] PRF initially provided pain relief, but symptoms recurred after 6 h; the patient subsequently underwent TRF, which resulted in more sustained improvement. Adverse effects related to PRF were mild. Bradycardia occurred in three patients – two in the super-voltage group (6.67%) and one in the standard PRF group (3.33%) – all managed successfully with atropine. In addition, two patients developed transient facial nerve neuropraxia, with no major complications or unplanned admissions. In contrast, studies using TRF reported mild oropharyngeal hypaesthesia, reduced gag reflex and palatal paresis in all patients. No major complications or hospital readmissions were reported.