Classifying Sphenopalatine Neuralgia as an Independent Clinical Entity

Lateral wall of the nasal cavity: cross-section showing the trigeminal nerve and sphenopalatine ganglion. Pen and watercolor drawing after Henry Gray, c. 1890.
In China, researchers found data from case studies that they believe support a separate classification of sphenopalatine neuralgia as an independent clinical entity that can be diagnosed using radiology.

Sphenopalatine neuralgia (SN) is currently classified as a phenotype of cluster headache but should be classified as an independent clinical entity into appendix code 13 of the International Classification of Headache Disorders (ICHD) and divided into 2 subtypes of idiopathic and secondary, according to a study published in Headache. This conclusion is based on various findings that study investigators state need further investigation as the original literature on SN is scarce.

This study consisted of 2 parts providing insight into underlying causes relating to the sphenopalatine ganglion. The first part was a case series analysis of 7 patients with SN who were referred to the study authors’ tertiary headache clinic of The First Affiliated Hospital of Chongqing Medical University in Chongqing, China. The second part was a literature review of 12 published studies on SN.

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Of the 7 patients, the median age at symptom onset was 59 years. Whereas 6 of the 7 cases were secondary to structural lesions around the ipsilateral sphenopalatine ganglion, in the 7th patient, no underlying disease was found. All patients experienced significant improvement in symptoms after the primary causes were addressed or via blockage of the sphenopalatine ganglia. The literature review revealed SN affects patients spanning a wide age range and both sexes. Although the clinical characteristics can mimic cluster headache excepting cluster pattern, they do not respond to oxygen treatment. Pain duration was typically several hours to several days and pain was persistent in some cases. Of the total 88 patients with SN, 67% (n=59) had structural lesions around the sphenopalatine ganglion. In these cases, etiological treatment relieved the headache, and in cases with no etiology, blockage of the sphenopalatine ganglia by cocainization or infiltration anesthesia was effective. Recurrence rate could not be determined due to the lack of follow-up data.

Study investigators conclude, “SN is an independent type of neuralgia. It is recommended that SN be classified into appendix code 13 of ICHD-3 and divided into 2 subtypes: idiopathic and secondary. The idiopathic etiology of SN may be related to demyelination of the sphenopalatine ganglion. In secondary SN, the presence of structural lesions around the sphenopalatine ganglion should be investigated. Radiological examination is required. The original literature on SN is scarce, and some cases cannot be analyzed because of inadequate data. The conclusions from this study require further investigation.”

He W, Zhang Y, Long T, Pan Q, Zhang S, Zhou J. Sphenopalatine neuralgia: An independent neuralgia entity. Pooled analysis of a case series and literature review [published January 11, 2019]. Headache. doi: 10.1111/head.13469