SUPRAORBITAL AND AURICULOTEMPORAL NERVE ENTRAPMENT: A LESSER-KNOWN CAUSE OF HEADACHE MIMICKING MIGRAINE-LIKE SYMPTOMS.

Extracranial headaches, although not rare, can be a signiﬁcant contributor to chronic headaches, aﬀec�ng approximately 4% of individuals. Among the poten�al causes of these headaches, entrapment neuropathy in the facial area is a prominent factor, with supraop�c nerve entrapment being a leading cause. The resul�ng pain typically manifests in the frontal forehead regions that are innervated by this nerve. Ultrasound-guided supraop�c nerve interven�ons serve a dual purpose, ac�ng as both a diagnos�c tool and a therapeu�c measure, oﬀering valuable beneﬁts in managing this condi�on.


INTRODUCTION
Supraorbital nerve (SON) and auriculoremporal nerve (ATN) entrapment is a rela vely uncommon cause of extracranial headache, as first described by Beyer in 1949.(1) SON & ATN entrapment occurs with an incidence of 4% & 0.4% and is characterized by pain in the nerve's territory and tenderness in the Supraorbital notch.(2,3) It can however, present with atypical manifesta ons that can mimic migraines and may lead to difficulty when differen a ng them from other types of headaches.Nerve block and hydrodissec on using local anesthe cs can aid in diagnosing the entrapment.(2,4).We report a case in which we successfully diagnosed SON entrapment through the u liza on of ultrasound-guided SON blockade and hydrodissec on.

CASE -1
A 41-year-old gentleman presented to our pain clinic with a four-year history of headaches, NRS of 8, localized in the frontal region.The pa ent consistently experienced headaches star ng at approximately 1 pm, which would progressively worsen throughout the night.The pa ent had been experiencing a consistent pa ern of pain with similar characteris cs.He described the pain as dull in nature, without any neuropathic characteris cs such as electric shock-like sensa ons.Previous evalua ons included visits to an ENT specialist and sinusi s treatment, but no improvement was observed.A neuro physician consulta on was conducted, and an MRI brain scan yielded normal results.Upon examina on, Tinels's test was nega ve, sugges ng no signs of nerve irrita on.The pa ent was provisionally diagnosed with migraine although the fixed me ini a on of symptoms raised doubts, and, treated for migraines but no observed benefits in relieving symptoms were noted.Considering the possibility of nerve entrapment, we planned a diagnos c supraorbital nerve under ultrasound guidance.By placing the hockey s ck probe (Fujifilm ARIETTA 750 3-15 HZ) horizontally across the supraorbital notch and directly visualizing the supraorbital foramen, we injected 1 ml of a mixture of 0.5% bupivacaine and Dexona 2 mg avoiding inadvertent injec on into the orbital foramen(Fig 1 ultrasound image).We reevaluated the pa ent on day 4 then day 10, when he reported a significant reduc on in pain, with a Numeric Ra ng Scale (NRS) score of 1 on both days.Based on the posi ve response to the nerve block, a diagnosis of supraorbital nerve entrapment was made.We achieved both advantages in our case.

CASE-2
A 35 year lady presented to our pain clinic with complain of electric shock like pain in le temporal region since 7 days.For same region she had visited emergency last night where codopar was prescribed and advised to visit medicine OPD.Pa ent directly visited pain clinic.On history pain started suddenly and severe in nature.Pain was received for 2-3 hours a er having codopar.Tinel's test was not posi ve which may be due to codopar.
Unilateral temporal, sudden onset and electric shock like pain sugges ng entrapment pain and diagnos c block was planned.0.5% Bupivacaine 2 ml under ultrasound guidance(Fujifilm ARIETTA 750, Hockey s ck probe 3-15 HZ) was injected posterior to temporal artery at the level of tragus.5 mins a er injec on there was swelling like feeling around ATN and even eye lids.Pa ent was informed to note dura on on analgesia and to take codopar a er onset of pain.On next visit she has slight pain but need not take codopar.We plan for non invasive Pulse Radiofrequency s mula on which was third day of injec on.On third day pa ent was comfortable and pain was decreasing so procedure was abandoned.

Superficial temporal artery
Site for auriculotemporal nerve block USG image for auriculotemporal nerve block, color doppler showing superficial temporal artery

DISCUSSION
In this case, we observed that the pa ent didn't have classical symptoms that were consistent with commonly known causes of headaches as migraines, cluster or tension headaches.The symptoms were neither associated with chronic neuropathies like trigeminal neuralgia nor did they resemble infec ous pain akin to postherpe c neuralgia.Pa ent had undergone mul ple sets of inves ga ons and treatments trials without experiencing any improvement.We made a decision to administer nerve Blockade, despite the fact that we didn't find features of neuropathic pain.
Administering a few milliliters of local anesthe c in the affected side can bring relief or complete resolu on of symptoms if the condi on is a ributed solely to nerve entrapment.The use of this nerve blockade offers two advantages.Firstly, it can serve as a diagnos c tool by confirming the diagnosis if the symptoms are alleviated.Secondly, it presents a 6 therapeu c op on to include in the treatment plan.Supraorbital nerve, a large lateral sensory branch of the frontal nerve, arises at supraorbital notch along the superior rim of the frontal bone anteriorly.The frontal nerve, a branch of the ophthalmic nerve, enters the orbit through superior orbital fissures.The frontal nerve also gives rise to medial small supratrochlear nerves that exit in the notch.Both nerves travel in vicinity to their arteries and supply sensory innerva on to the forehead, upper eyelid, and anterior scalp.(Fig 2 )The most common cause of supra op c neuralgia is compressed acutely at supraorbital notch.In the majority of cases, both no ceable and subtle trauma have been iden fied as contribu ng factors to compression.The differen al diagnosis are ophthalmic(V1) trigeminal neuralgia, supratrochlear neuralgia, external compression headache, primary stabbing headache, hemicrania 6 con nua, nummular headache etc.
Auriculotemporal nerve is sensory branch of mandibular nerve supplying temporomandibular joint , paro d region, ear and lateral scalp.Auriculotemporal neuralgia is more common among women: 85.3% of the cohort in Damarjran There are several treatment op ons available for addressing the nerve entrapment.The ini al course of ac on in treatment of nerve entrapment involves the use of oral medica ons such as carbamazepine, gabapen n, and pregabalin.Addi onally, an ultrasound-guided nerve block can be administered using local anesthe cs, with or without the inclusion of glucocor coid.This technique aims to relieve pain by blocking the nerve and u lizing hydrodissec on to alleviate discomfort.Chemical neurolysis is also considered as a poten al treatment, and surgical resec on of the supraorbital nerve may be pursued in certain cases.Cryoneuroabla on, a technique that uses extreme cold to disrupt nerve func on, is another available op on.Addi onally, radiofrequency thermocoagula on can be employed as a treatment method.For those seeking non-destruc ve procedures, surgical decompression of the supraorbital nerve or pulsed radiofrequency therapy may be recommended.(10) To accurately diagnose various types of entrapment neuropathy, it is crucial to maintain a high level of suspicion.These neuropathies occur as a result of chronic compression, affec ng the peripheral nerves and causing symptoms like pain and impaired motor or sensory func on.Compression or entrapment of nerves is not limited to the extremi es; the nerves in the trunk, head, and neck are also suscep ble to such condi ons.The compression commonly occurs when a nerve traverses through narrower foramina or spaces, leading to poten al nerve impingement or entrapment.This can result in various symptoms and func onal impairments associated with nerve compression in the dermatomes supplied by the The following criteria are used to diagnosed supraorbital neuralgia according to the 2nd edi on of the Interna onal 7 Classifica on of Headache Disorders (ICHD-2): .Auriculotemporal neuralgia is not individually men oned 11 but trigeminal nerve is included in ICHD.
1. Presence of paroxysmal or constant pain in the specific area of the forehead supplied by the supraorbital nerve, extending from the supraorbital notch to the medial aspect of the forehead.2. The supraorbital nerve exhibits tenderness when pressure is applied at the supraorbital notch.3. Relief from pain occurs when the supraorbital nerve is blocked with local anesthesia or when it undergoes abla on.These criteria serve as a diagnos c tool for iden fying supraorbital neuralgia in individuals presen ng with typical symptoms.Supraorbital neuralgia is now categorized as a cranial neuropathy in the Interna onal Classifica on of 9 Diseases 11th Revision (ICD-11) .In cases where individuals do not meet all three criteria, a supraorbital nerve block can be performed to aid in the diagnosis.The procedure is generally safe and does not carry significant complica ons.

Figure 2 :
Figure 2: Sensory Distribu on of nerves in the face.