Great auricular neuralgia: case series

The great auricular nerve (GAN) leaves the C2-C3 cervical rami, wraps around the sternocleidomastoid muscle, then divides into: anterior branch (skin over preauricular, parotid, jaw angle) and posterior branch (skin over mastoid and posteroinferior pinna). GAN damage is well described with procedures nearby the nerve course. However, neuralgia of this nerve is uncommon, and its knowledge is based on a handful of case reports.


INTRODUCTION
The superficial cervical plexus is formed by the ventral rami of the first 4 cervical nerve roots, with 4 superficial cutaneous branches all emerging from the posterior border of the sternocleidomastoid (SCM) muscle: great auricular nerve (GAN), lesser occipital nerve (LON), transverse cervical plexus, and supraclavicular nerves. The GAN, originating from the C2-C3 nerve roots, emerges from the mid-point of the SCM, wraps around the belly of the muscle and ascends as it splits into an anterior branch (innervating the skin over the pre-auricular region, parotid, and mandibular angle) and posterior branch (innervating the skin of the posterior-inferior pinna), see Figure 1. In cadaver studies, just over a third of GAN nerves have a mastoid branch that communicates with the LON posteriorly and contributes to additional sensory innervation just behind the ear. 1 Given its superficial location, the GAN is easily injured during procedures nearby the nerve course, including parotidectomy, 2 submandibular gland resection, 3 rhytidectomy (face-lift), 4,5 cervical lymph node dissection, trauma, 6,7 carotid endarterectomies, 8 and even pacemaker placement. 9 In addition to the reduced sensation, the injury-associated neuropathy is often uncomfortable, with possible paresthesia, dysesthesia, and allodynia. Most patients have gradual improvement in their discomfort during the first year after surgery, but a small number of patients continue to have discomfort to the point that it reduces quality of life, even years after surgery. 2,10,11 For this reason, many centers are attempting to modify their surgical practices to preserve the GAN and other superficial branches of the cervical plexus. [12][13][14] A more rare pain presentation in the GAN distribution is that of neuralgic pain, in the absence of neuropathy. Neuralgia of the GAN is described as brief attacks of sharp, lancinating pain along the lateral neck, jaw, and outer ear, without associated sensory impairment. GAN neuralgia is relatively rare and understanding of this entity is based on a handful of case reports. 3,9,[15][16][17][18] We present an additional 13 cases of GAN neuralgia seen at our institution.

METHODS
Study Design.-This is a case series of patients seen at a tertiary outpatient medical center in Rochester, MN. The study period included patients seen from January 1, 1994 and May 31, 2018. The study was deemed exempt by our institutional review board. Written informed consent was obtained for participating patients.
Collection of Data.-We used Advanced Cohort Explorer to search clinical records for the search terms: "auricular neuralgia," "auricular neuritis," or "auricular neuropathy." Cases were reviewed initially by a single author (JD or CR), and final included cases were reviewed by more than one author to ensure that there was agreement on patients meeting both inclusion and exclusion criteria. We included cases of neuralgic (sharp, stabbing, shooting, lancinating) pain in the distribution of the GAN in the absence of sensory loss. We excluded cases with missing information, alter native neuralgias, GAN neuropathy, atypical facial pain, pain of unclear etiology and neuralgic pain in the distribution of the GAN without associated triggers ("possible GAN"), see Figure 2.
Collected data included demographic information (eg, age at symptom onset and gender) and clinical history including: description and location of pain, provocation maneuvers, concurrent migraine history, neurologic examination, diagnostic evaluation, presumed etiology, response to treatment, and long-term outcome.

RESULTS
Of 79 charts reviewed, 13 patients met criteria (11 women, 2 men; range of age at onset: 11-59), see Table 1. All patients described brief sharp severe pain in the distribution of the GAN. Five patient charts documented an estimate of the duration of pain, with 4 patients describing pain lasting seconds and 1 patient describing pain "typically lasting seconds, but sometimes up to 1-2 minutes." Patients who did not have a documented estimate of duration described their pain most often as either "paroxysmal stabbing" or "shooting," with a few describing pain as "electric shock-like" (n = 3) or "lancinating" (n = 2). In addition to their neuralgic pain, 6 patients had a persistent background pain, described as follows: pressure/fullness (n = 2), a combination of dull and burning (n = 2), and dull/ aching (n = 2). The most common provoking maneuver for pain was turning the head/neck (n = 7). Additional provocation maneuvers included touching the neck  (n = 5), neck position during sleep (n = 2), jaw movement such as eating/yawning/talking (n = 2), exertion (n = 1) and lifting with the ipsilateral arm (n = 1). Two patients had prominent redness/flushing of their ear with their neuralgic pain (rows 3 and 6 in the Table 1). Presumed etiologies of GAN neuralgia in our series included idiopathic (n = 7), trauma from tympanomastoid procedures (n = 2), low-grade lymphoma of GAN, idiopathic lymphadenopathy, Sjogren's syndrome, and blunt trauma from a coat rack falling on neck. Of note, 3 patients with "idiopathic" GAN neuralgia were noted to have a history of cervical arthritis.
The majority of patients received various neuropathic medicines without significant relief. One patient reported improvement on gabapentin and another reported carbamazepine to be somewhat helpful. The patient with lymphoma within the GAN had resolution of pain following nerve resection. Seven patients received GAN blocks and all 7 noted dramatic improvement in their pain. Three patients continued to receive serial GAN blocks with prolonged pain relief (follow-up ranging 2 to 5 years). One patient experienced resolution of GAN neuralgia pain after 2 successful GAN blocks; she was still pain-free at her 2-year follow-up. One patient experienced complete relief for an average of 6 to 7 weeks after each of 2 GAN blocks; she was subsequently lost to follow-up. The other 2 patients transitioned from GAN blocks to GAN stimulators with almost complete resolution of their pain. Both GAN stimulators were pulse generators with 8-contact leads placed over the GAN near where it crossed the SCM, with multiple electrode combinations utilized to maximize coverage over the painful territory.
Interestingly, one of the patients with a GAN stimulator developed a persistent mid-frontal headache with migrainous features immediately following the stimulator placement, and developed seizures of unclear etiology 1 year later. She turned down multiple offers to discontinue the stimulator, out of fear that her ear pain would return. The other patient with a stimulator was able to discontinue all neuropathic medicines while stimulated. Fourteen months after stimulator placement, she fell on ice and had a return of her severe pain. After stimulator reprogramming, her pain resolved and she remained essentially pain-free at a 1 year follow-up.
Representative Cases.-Case 1.-A 41-year-old woman with history of episodic migraine in childhood presented with paroxysmal pain involving the right pre-auricular, post-auricular, and upper lateral neck region (behind the mandible) that began suddenly, without clear cause, 1 year prior to presentation at our institution. She described the pain as suddenonset, severe, sharp, stabbing pain provoked by turning her head ipsilaterally and at times by touching the area. Repetitive stabs would occur in clusters that were typically brief, but could last up to 1 to 3 days. These episodes occurred an average of once per month. She was pain-free between attacks. She described the pain as clearly different from the migraine headaches that she experienced when she was younger, which were frontal, throbbing, and associated with photophobia and phonophobia. Her neurologic examination was normal without evidence of anesthesia in the distribution of the GAN. Diagnostic evaluation including MRI brain with and without gadolinium contrast and MRI cervical spine revealed some mild cervical degenerative disc disease, but was otherwise unremarkable. Various neuropathic medications including gabapentin, pregabalin, carbamazepine, baclofen, and sumatriptan did not provide any noticeable pain reduction. Serial GAN blocks have been performed for the past 3 years, each one providing her excellent relief of pain (90-100%) for about 4 months.
Case 2.-A 56-year-old woman with history of pulmonary sarcoidosis presented with a 2-month history of intermittent pain involving the post-auricular area and the posterior ear canal on the right. She described the pain as severe, sharp, and stabbing, lasting several seconds up to a minute or two. Pain could be triggered by touching her neck over an area of swelling that had been enlarging over the same 2-month period. MRI of the face with and without contrast showed abnormal soft tissue enhancement involving the superficial aspect of the right parotid gland directly inferior to the right ear pinna, see Figure 3. There was suspicion that this may represent infiltration by sarcoidosis; however, surgical pathology revealed low-grade lymphoma. The operative note by the otorhinolaryngologist noted that "the GAN was enlarged in the distal portion and was abnormal appearing." Following GAN resection, she did experience numbness and periodic paresthesias involving the right ear lobe and jaw; however, her neuralgic pain resolved.
Gan Neuropathy and Possible Gan Neuralgia.-Of the 79 cases reviewed, 7 patients were found to have GAN neuropathy, one of whom had concomitant neuralgic pain. Etiologies for GAN neuropathy were most commonly iatrogenic secondary to head and neck procedures (n = 5) including parotidectomy for pleomorphic adenoma (n = 2), carotid endarterectomy (n = 1), lymph node dissection (n = 1), and glossectomy and cervical dissection for small cell carcinoma of the tongue (n = 1). One patient had GAN neuropathy secondary to Sjogren's syndrome.
Two patients had neuralgic pain in the distribution of the GAN but were eventually classified as "possible GAN neuralgia," because there were no identifiable triggers, no dysesthesia and/or allodynia apparent during innocuous stimulation of the innervation area, and no prominent tenderness along the lateral neck where the GAN courses the SCM. One of these patients had associated idiopathic GAN neuropathy and eventually received a GAN block. She had only a 24-hour follow-up after her block; however, so her response to block was unknown. The other patient had additional constant pain but no neuropathy in the GAN distribution, and had an excellent response to a GAN block, with reduction of pain for 2 weeks.

DISCUSSION
The first case of GAN neuralgia was described in 1932, when a 60-year-old man experienced paroxysmal pain involving the "outer shell of the left ear… especially over the lower part of the ear." His attacks occurred at 2 to 3 week intervals, were more prominent in colder months, and could be triggered by rubbing over his ear. GAN neuralgia in this patient was thought to be secondary to cervical arthritis. 18 In 1992, Blumenthal described a case of GAN neuralgia following pacemaker placement, and commented that additional discussion on the anatomy of the GAN was warranted in neurologic and headache literature, as GAN neuralgia had been left out of 2 extensive reviews of head and neck neuralgia at that time. 9 Over 25 years later, GAN neuralgia continues to be left out of extensive reviews of well-known and lesser-known neuralgias of the head and neck. 19,20 In our review of cases at our institution, there was obvious confusion distinguishing GAN neuralgia from GAN neuropathy, as well as from neighboring neuralgias. This confusion has occurred in the literature as well. 21 To make matters more complicated, occasionally patients with GAN neuropathy can have superimposed neuralgic pain and there is very little guidance for how to classify these pain syndromes.
To help with the clinical evaluation of these patients, we propose that GAN neuralgia be added to the International Classification of Headache Disorders, 3rd edition (ICHD-3). 22 In keeping with criteria for other craniocervical neuralgias, we would propose that the pain be described as neuralgic (paroxysmal, sharp, lancinating) in nature, and remain within the distribution of the GAN (see Fig. 1). Also similar to criteria for other neuralgias, we suggest that GAN neuralgia should be triggerable, either by innocuous stimulation within the GAN dermatome or by irritation of the GAN as it ascends along the SCM, such as turning the head or a positive Tinel's (see Table 2 for proposed criteria). All of the 13 patients in our series met the clinical criteria as proposed, though 5 patients have not had a GAN block.
Evaluation.-It has been suggested that the GAN is most superficial, and therefore most vulnerable to iatrogenic injury, as it emerges from the posterior border of the SCM, an area sometimes referred to as "McKinney's point." This is approximately 6.5 cm caudal to the external auditory canal, or about onethird the distance from the external auditory canal to the clavicular origin of the SCM, along the posterior border of the SCM. 23,24 This is roughly the location recommended for surface stimulation when performing nerve conduction studies of the GAN. 21,25 This is also likely the best place to attempt a Tinel's maneuver when evaluating patients for possible GAN neuralgia.
Like other types of neuralgia, GAN neuralgia can be either idiopathic or secondary to an underlying etiology. In our series, 6 patients (46%) were felt to have secondary GAN neuralgia, including cases of iatrogenic injury, trauma, inflammation, and neoplasm. This list is consistent with the types of secondary cases of GAN neuralgia reported in the literature. 3,9,[15][16][17][18] Given our case of GAN lymphoma and other reports of perineural spread of squamous cell carcinoma into the GAN, 26-28 we would recommend a low threshold for imaging of the soft tissues of the neck in a patient with systemic symptoms, progressively worsening pain, or a history of cancer. As there is dermatomal overlap of multiple sensory nerves innervating the ear and throat, an MRI or CT of the neck with contrast would also help evaluate for referred ear or jaw pain related to pathology around the ear, parotid, throat, thyroid, and surrounding structures. 29,30 Because the GAN and Table 2.

Description:
A disorder characterized by unilateral brief stabbing pain, abrupt in onset and termination, in the distribution of the great auricular nerve (preauricular, parotid and jaw angle and/or posteroinferior pinna and mastoid). It is commonly provoked by neck rotation and may remit and relapse similar to other craniocervical neuralgias Diagnostic criteria: A. Paroxysmal attacks of unilateral pain in the distribution of the great auricular nerve (GAN) 1 and fulfilling criterion B-D below: B. Pain has at least 2 of the following 3 characteristics: 1. Recurring in paroxysmal attacks lasting from a few seconds to minutes 2. Severe in intensity 3. Shooting, stabbing or sharp in quality C. Pain is associated with one of the following: 1. Dysaesthesia and/or allodynia apparent during innocuous stimulation of the innervation area 1 2. Precipitation by neck rotation 3. Prominent tenderness or Tinel's along the lateral neck where the GAN courses the sternocleidomastoid D. Pain is eased temporarily by local anesthetic block of the affected nerve E. Not better accounted for by another ICHD-3 diagnosis Notes: 1. Pain is located in the pre-auricular, parotid and jaw angle (anterior branch) and/or the mastoid and posteroinferior pinna (posterior branch) 2. Similar to trigeminal neuralgia, GAN neuralgia should be distinguished from GAN neuropathy. GAN neuropathy pain is usually continuous or near-continuous, and commonly described as a burning, paresthesia, or dysesthesia. While brief paroxysms (neuralgia) may be superimposed, they are not the predominant pain type. GAN neuropathy is accompanied by reduced or absent sensation somewhere within the distribution of the GAN. This sensory deficit does not have to include the entire sensory dermatome.
other branches of the superficial cervical plexus originate from the first 4 cervical ventral rami, imaging of the cervical spine could also be considered in select cases. Cervical degenerative changes were found in 3 of our patients (labeled as idiopathic GAN neuralgia), and have been described in the literature. 15,17,18 Even in cases of iatrogenic GAN neuropathy with superimposed neuralgia, if the pain is out of proportion to the neuropathy, imaging might be considered to evaluate for post-surgical GAN neuroma. 31 Some have recommended high resolution ultrasound as a sensitive way to assess for pathology along the superficial GAN. 32 Interestingly, 2 of our patients had associated redness and flushing of the ear ipsilateral to their pain, associated with their attacks. One of the excluded patients who had neuralgic pain in both GAN and LON distributions responsive to blocks also had flushing of her ear with attacks, and previously carried the diagnosis of "red ear syndrome." Red ear syndrome is typically described as burning and redness over the ear, sometimes precipitated by touching the area or head/neck movements. [33][34][35][36] An overlap with auriculotemporal neuralgia has been suggested, though typical pictures of the erythema show redness in the posterior pinna, more typical of the distribution of the GAN. 34,36,37 Seleker and colleagues reported a case of red ear syndrome with classical burning pain as well as tenderness along the GAN, ultimately responsive to GAN blockade. 38 Their case along with our cases may suggest GAN blockade as a possible treatment in select patients with red ear syndrome.
Treatment.-In our series, 1 patient felt gabapentin was helpful, and another reported modest relief with carbamazepine. The rest of the patients in our series found minimal relief with medication, including trials of medicines typically used for neuropathic pain, such as antidepressants, anticonvulsants, or opioids. However, patients may have had short duration or subtherapeutic trials of these medicines. In some cases, medicines were tried for only 2-3 weeks. Interestingly, 1 patient with concurrent chronic migraine regularly received onabotulinumtoxinA injections and commented that these treatments did not help her GAN neuralgia pain, but seemed to "stop the GAN pain at the ear," without allowing it to ascend up and over her head to trigger a severe migraine exacerbation. In our series, 7 patients received GAN blocks, and all noted dramatic improvement in their pain.
GAN Blocks and Stimulators.-Early blocks of the GAN involved large volumes of anesthetic agents, with complete blockade of the superficial cervical plexus. 39,40 More recently, targeted blocks to the GAN have been reported, using either landmark or ultrasound guidance. 16,38,39 In a study using 20 volunteers, Thallaj and colleagues found that it was easiest to identify the GAN on ultrasound when it is deep and medial to the SCM, as the cross section of the GAN is visible twice in 1 image, as 2 round hypoechoic structures located deep and superficial to the SCM. They were then able to trace the superficial nerve as it ascended along the SCM until its bifurcation, in order to confirm that the injection was given proximal to the bifurcation. 39 In their series, Thallaj and colleagues reported a 100% successful GAN blockade (based on pinprick testing over the pinna), using only 0.1 mL of 1% mepivacaine. 39 It is notable that they used only healthy male volunteers, however, and it has been suggested that this block may be more difficult in female or obese patients. 1,41 Anatomical variation might affect the success of GAN blockade in a more diverse patient population, as cadaver studies have shown variation not only in the bifurcation, but in where the GAN crosses over the SCM in a substantial number of patients. 14,42 In 1 study of 100 patients scheduled for shoulder or upper arm surgery, the anesthesiologist was unable to identify the GAN either by ultrasound or transcutaneous nerve stimulation in 29 patients; however, the combination of these 2 techniques increased the identification of the nerve to 95%. 1 Similar to other institutions, our institution does not have a mandatory protocol for nerve blocks; instead, the technique is based on the preference of the pain physician and the patient (based on response to previous blocks). The majority of GAN blocks in our series were performed with ultrasound guidance, with most patients receiving approximately 3-5 mL of injectate (range 2-7 mL) along the posterior border of the SCM, where the GAN was visualized to emerge. Injectate consisted of a combination of steroid (1.5-3 mg betamethasone, 1 mg dexamethasone, 20-40 mg ztri amcinolone, or 10 mg depo-methylprednisolone) and anesthetic (2% lidocaine, 0.5% bupivacaine, or 0.5% ropivacaine). One of the physicians performing GAN blocks in our study used a landmark-based technique, rather than ultrasound. He described "insertion of the needle along the lateral neck, approximately 2 cm below the mastoid process and pinna," presumably near the bifurcation of the GAN. When seen in follow-up after each of 2 consecutive landmark-based blocks, 1 patient noted that the block was most effective when she had transient complete anesthesia of the lower ear.
Two of our patients did have a GAN stimulator placed, and continued to be pleased with the reduction in GAN pain at their last follow-up visit. GAN neuromodulation has been reported in the literature as a treatment for chronic daily headache and post-traumatic headache, 43,44 though the authors commented that satisfactory pain relief after a GAN block served as an important factor in identifying appropriate candidates for GAN neuromodulation. They also recommended establishing an International Headache Society diagnosis before consideration of any device-based therapy, 43 highlighting the need for inclusion of GAN neuralgia in the ICHD-3 criteria. None of our patients underwent GAN decompression, but post-surgical GAN neuralgia has been rarely found to be associated with entrapment of the GAN in dense fibrous scar tissue, and these cases may respond to decompression. 3 Study Limitations.-Our study was a retrospective review and we were therefore limited to the information available in the charts. A prospective study would be helpful for a more detailed assessment of presentation and response to therapy, including GAN blockade and stimulation. It is possible that we missed additional cases of GAN neuralgia seen at our institution, as we excluded patients with unclear diagnoses (such as complex pain syndromes or neuralgic pain in multiple dermatomes), even if they did improve with GAN blockade.

CONCLUSION
GAN neuralgia should be considered in the differential for paroxysmal stabbing periauricular pain, especially in a patient who can provoke the pain by turning the head or touching the lateral neck or pinna. We propose that diagnostic criteria for GAN neuralgia be included in the Internal Classification of Headache Disorders to help clinicians differentiate this entity from GAN neuropathy, other cranial neuralgias and alternate etiologies of periauricular pain, including head and neck pathology. Like other craniocervical neuralgias, GAN neuralgia may be idiopathic or secondary to underlying pathology. If a patient presents with GAN neuralgia concurrent with GAN neuropathy, this should increase clinical suspicion for a secondary etiology. If there is no known history of iatrogenic injury, or if the neuralgic and neuropathic symptoms are disproportionate to what is expected, inflammatory or neoplastic etiologies should be considered. For pain management, consideration should be given to GAN blocks or stimulators, as these appear to offer greatest benefit for patients in these cases.