Non-traumatic supraorbital neuralgia: A clinical study of 13 cases *

Abstract

Introduction:

Supraorbital neuralgia (SON) is an uncommon disorder characterized by pain in the area supplied by the supraorbital nerve, which covers the medial aspect of the forehead, together with tenderness over the supraorbital notch or along the course of the nerve. Few hospital-based series of non-trauma SON have been published.

Methods and results:

We prospectively analyzed 13 patients (11 females, two males) diagnosed with SON in a headache outpatient clinic over a four-year period. Background pain was mostly dull and of moderate intensity. In addition, nine patients reported sharp, burning or stabbing exacerbations of severe intensity. Eight cases were treated with an anesthetic blockade and achieved complete relief lasting from two to six months. Three patients also received gabapentin, with no or only slight improvement.

Conclusion:

Non-traumatic SON is an uncommon disorder in our headache clinic. Female preponderance and clinical features are comparable to the data collected in previous studies. A spontaneously remitting pattern is not uncommon, and anesthetic blockades are not always required.

Introduction

The supraorbital nerve is a pure sensitive terminal branch of the ophthalmic division of the trigeminal nerve. It leaves the orbit through the supraorbital notch and, with the supratrochlear nerve, is responsible for the innervation of the skin of the forehead, eyelid, conjunctiva and the frontal sinus. The supraorbital nerve is located in a superficial position especially vulnerable to compression or trauma (1).

Supraorbital neuralgia (SON) is an uncommon disorder, which was included among the cranial neuralgias in the second edition of the International Classification of Headache Disorders (ICHD-II) (2). According to the ICHD-II diagnostic criteria, SON is characterized by paroxysmal or constant pain in the medial aspect of the forehead, with tenderness over the supraorbital notch and along the course of the nerve. For definite diagnosis, the pain must be also abolished by local anesthetic blockade or ablation of the nerve.

SON is believed to be an uncommon pain syndrome. Most reported cases have a traumatic origin. Little is known about its prevalence. Only one population-based epidemiological study has been performed, with a prevalence estimation of 0.65%. The prevalence decreased to 0.15% when only non-traumatic cases were considered (3). Two hospital-based series of SON have been published so far (4,5), the more extensive including 18 patients (4).

We aim to report the demographic and clinical characteristics as well as the therapeutic responses in a consecutive series of 13 new cases of non-traumatic SON.

Methods

Through a four-year study period (January 2008 to January 2012), we included all consecutive patients diagnosed with SON according to ICHD-II criteria at our outpatient headache clinic. This clinic is located in a tertiary hospital covering a health regional area of 260,000 inhabitants. We took special care not to induce false answers during the interviews. A detailed history was obtained from each patient, including coexistence of other types of headache or previous ophthalmologic diseases. We excluded post-traumatic cases. We registered demographic data (sex, age, age at onset). Pain characteristics were carefully evaluated, including temporal and spatial features, background pain (quality, intensity) and exacerbations (frequency, periodicity, quality, intensity).

We performed a complete physical and neurological examination of every patient, including inspection and sensory examination of the painful area. We palpated the supraorbital notch as well as the infraorbital, supratrochlear, minor occipital and greater occipital nerves. Computed tomography (CT) or magnetic resonance imaging (MRI) of the head and the orbit were obtained in all cases in order to exclude underlying lesions.

We assessed the effectiveness of any former or subsequent drug, as well as the requirement and response to anesthetic blockades of the supraorbital nerve.

Results

Thirteen patients (11 female, two male) out of 1668 patients attending our headache clinic during the study period were diagnosed with SON. This represents a proportion of 0.8%. The main demographic and clinical features of our 13 patients are summarized in Table 1.

Table 1.

Demographic and clinical features of this series of patients with non-traumatic supraorbital neuralgia.

Number	1	2	3	4	5	6	7	8	9	10	11	12	13
Sex (M/F)	F	F	F	F	F	F	F	F	F	M	F	F	M
Age at onset (years)	45	59	39	35	55	31	16	24	45	83	66	48	62
Laterality (R/L)	L	L	L	R	L	R	L	L	R	R	R	L	L
Other headaches	No	No	No	No	No	TTH	Mig aura	No	Mig	No	No	No	Mig
Temporal pattern	Chr	Rec	Rem	Rec	Chr	Chr	Chr	Rem	Chr	Rem	Rec	Chr	Chr
Background pain
Character	Pres	Pres	Pres	Pres	Stab	Pres	Pres	No	Pres	No	No	Pres	Burn
Intensity*	5	4	8	4	6	6	5	—	5	—	—	5	5
Exacerbations
Duration	10sec	2min	—	15min	3sec	—	—	30sec	—	2sec	2min	3sec	10min
Character	Burn	Stab	—	Pres	Stab	—	—	Pres	—	Throb	Stab	Throb	Burn
Intensity*	8	10	—	7	10	—	—	9	—	8	5	8	7

M: male; F: female; R: right; L: left; TTH: tension-type headache; Mig: migraine; Chr: chronic; Rem: remitting; Rec: recent; Pres: pressing; Stab: stabbing; Burn: burning; Throb: throbbing; Sec: seconds; Min: minutes. *VAS: Visual analogical scale (0: no pain, 10: the worst pain imaginable).

Mean age at onset was 46.3 ± 18.2 years (range: 16–83). Pain was strictly unilateral in all the patients. In five cases (38.5%) the pain was right sided, and in the remaining eight (61.5%) it was exclusively left sided. None of the patients had a history of forehead trauma on the symptomatic side. Three patients also suffered from migraine (one of them with aura) and one from tension-type headache, but no temporal or spatial relationship was found between the symptoms of SON and these other headaches.

The pain was always located in the medial forehead, and it could be elicited by pressure on the ipsilateral supraorbital notch in all the patients. None of them had sensory dysfunction such as hypoesthesia or allodynia in the symptomatic area. Otherwise, no autonomic or migrainous accompaniments were reported.

Regarding the temporal pattern, SON was chronic (without significant remission periods) in six (46.1%) patients, episodic with spontaneous remissions in four (30.8%), and too recent to be determined (time from onset less than three months) in three (23.1%) cases.

Ten (76.9%) patients reported a constant background pain, described mostly as pressing (eight, 61.5%), and rated as 5.3 ± 1.1 (range: four to eight) on a verbal analogical scale (VAS) (0: no pain, 10: the worst imaginable pain). Stabbing, throbbing or burning exacerbations were registered in nine cases (69.2%). These exacerbations lasted from 2 seconds to 15 minutes, and were rated as 8 ± 1.6 (range: 5–10) on the VAS. Three cases had only intermittent pain.

Three patients (23.1%) had previously received an anti-neuralgic drug (gabapentin) and three (23.1%) at least one non-steroid anti-inflammatory drug (NSAID) before being referred to our headache clinic. These drugs provided no or only slight improvement.

Eight patients (61.5%) were treated with at least one anesthetic block. Anesthetics were injected 2 centimeters lateral to the medial border of the eyebrow as recommended (6). We used 0.5 cc of a mixture of bupivacaine 0.5% and mepivacaine 2% in a 1:1 ratio. All patients reported complete relief. Improvement began immediately after the procedure and lasted from two to six months. When blockades were repeated, the free pain period increased slightly with subsequent procedures. Therapeutic responses are summarized in Table 2.

Table 2.

Therapeutic characteristics of 13 patients.

Number	NSAIDs	Gabapentin	Anesthetic blockade (number)	Time of relief (months)
1	NT	NT	Total relief (1)	3
2	Partial relief	NT	Total relief (1)	6
3	NT	NT	Total relief (1)	6
4	NT	NT	Total relief (1)	6
5	No relief	No relief	Total relief (1)	2
6	NT	NT	Total relief (3)	2, 2, 3
7	NT	NT	NT	—
8	NT	No relief	NT	—
9	NT	NT	Total relief (1)	2
10	NT	Partial relief	NT	-
11	NT	NT	NT	-
12	Partial relief	NT	Total relief (2)	2, 3
13	NT	NT	NT	-

NSAIDs: non-steroid anti-inflammatory drugs; NT: not tried.

Discussion

The term “epicranial neuralgia” defines a pain in the territory supplied by a pericranial sensory nerve. Pain arising from lesions or dysfunctions of pericranial nerves, such as the supraorbital branch, usually attains a chronic-continuous pattern instead of the brief and abrupt paroxysms commonly described in neuralgias with an intracranial source (7). The supraorbital nerve is located in a superficial position susceptible to compression or trauma. Entrapment mechanism for frontal bone or tissue band has been described as possible pathogenesis. Surgical procedure has been reported with long-term pain relief (5).

SON is characterized by unilateral forehead pain with a paroxysmal or constant temporal pattern, and is included among the “cranial neuralgias” in the ICHD-II (2). The scarcity of reports to date indicates that primary SON is either a rare disorder or an under-recognized condition in clinical practice. The proportion of non-traumatic SON in our headache clinic registry is only 0.8%, in line with previous communications.

As was shown in the longest series published up to now (4), we have observed a clear female preponderance and a mean age at onset in the fifth decade of life. The temporal pattern has been described as mostly chronic-continuous or remitting-intermittent (4,8). Our patients commonly suffered a constant pressing background pain of moderate intensity with a high percentage of spontaneous remissions (30.8%). Most of our cases also presented brief exacerbations of severe intensity superimposed on the background pain, but in only three of them they were the only pain pattern described.

The clinical picture of post-traumatic SON differs from that found in idiopathic SON. First, it has a predominance of males instead of the female preponderance of non-traumatic SON (9). Second, it frequently combines sensory dysfunction with hypoesthesia, paresthesia or allodynia (10), while these signs and symptoms are very rare in primary SON (8,9). None of our patients had sensory dysfunction. Tenderness over the supraorbital notch and triggering of the pain by pressure over the nerve were considered diagnostic criteria in all of them, since pain had a typical distribution and was not elicited by any other external stimulus.

Migrainous features such as nausea, vomiting and photo-phonophobia, or local autonomic accompaniments, such as conjunctival injection, lacrimation or rhinorrhea are seldom reported in SON (8) and have not been found in our series. These features help to make a correct differential diagnosis between SON and other syndromes occurring in a similar location such as V-1 trigeminal neuralgia, hemicrania continua or other trigeminal autonomic cephalalgias. SON can be differentiated from primary stabbing headache, nummular headache, suprathroclear neuralgia or throcleodynia based on the exact location of the pain and tenderness over the supraorbital notch (8).

Absolute but transient relief with a local anesthetic blockade is considered a diagnostic criterion (2,4,11). Long-lasting effectiveness of blockades like that noticed in our series has already been described (4). We have also observed a slight increase in the time of response with subsequent procedures, as has already been reported for hemicrania continua (12). We did not used steroids, but the addition of steroids to anesthetics has not provided a longer effect (4). Given the presence of a temporal pattern with spontaneous remissions in some of our patients, an anesthetic blockade was not always required. According to different reports, indomethacin or other NSAIDs and antineuralgic drugs have been also used, with no consistent effects. Some patients have experienced partial relief with pregabalin (4) or gabapentin (4,13). If the pain becomes refractory to anesthetic blocks, neurostimulation techniques with the placement of a transitory or permanent stimulator in the supraorbital nerve distribution may be considered as a therapeutic option (11,14).

Conclusion

Non-traumatic supraorbital neuralgia is an uncommon disorder in our headache outpatient office. In our series both the gender distribution and the clinical features are comparable to those previously published. A spontaneously remitting pattern is not uncommon, and anesthetic blockades are not always required.