Occipital Neuralgia and Its Management: An Overview
Correspondence Address: Source of Support: None, Conflict of Interest: None DOI: 10.4103/0028-3886.315978
Source of Support: None, Conflict of Interest: None
Keywords: Headache, hypermobility, nerve entrapment, neuropathic pain, occipital neuralgia, trigeminal autonomic cephalalgia
According to the International classification of headache disorders, third version (ICHD-3), occipital neuralgia (ON) is defined as “unilateral or bilateral paroxysmal, shooting or stabbing pain in the posterior part of the scalp, in the distribution of the greater, lesser and/or third occipital nerves, sometimes accompanied by diminished sensation or dysesthesia in the affected area and commonly associated with tenderness over the involved nerve.”
In most cases, ON is considered idiopathic; however, case reports have shown that it could be related to specific causes such as trauma, rheumatoid arthritis, and nerve entrapment. Usually, the clinician's definitive diagnosis comes from the observation that the pain is provoked by a greater occipital nerve (GON) and/or lesser occipital nerve (LON) manipulation, and relieved by nerve block of the same. Because the neuronal information that reaches the cerebral cortex converges from different orofacial pain structures with highly complex nerve supply patterns, the process of making an accurate diagnosis becomes challenging for the clinician. A good history and clinical examination are fundamental to achieving proper diagnosis and therefore, an effective treatment plan.
A 15-year-old male Indian patient presented with a chief complaint of spontaneous attacks of excruciating pain in the right side of the face, specifically in the periorbital and retro-orbital area, temple, ear, and “referring to the neck.” Additionally, the patient had autonomic symptoms, including ipsilateral sinus congestion, and ipsilateral lacrimation. The frequency of the attacks was “random,” three to seven times per day, at three to 4-h intervals, with bouts lasting approximately ten minutes. Within each bout, there would be multiple attacks lasting less than a minute each. The patient or parents identified no precipitating or aggravating factors. Alleviating factors included an oxygen non-rebreathing mask, which gave marginal pain relief. No relevant medical or trauma history was elicited. The patient exhibited moderate generalized joint hypermobility. After seeking a diagnosis with several specialists, a neurologist diagnosed the patient with cluster headache, and prescribed oxygen therapy and prednisone; the pain persisted. An otorhinolaryngologist had diagnosed the patient with seasonal allergies. While reviewing the computed tomography (CT) done earlier elsewhere, we identified a mucus retention cyst of the right maxillary sinus, which was then subsequently removed by the Otorhinolaryngologist [Figure 1].
Consequently, the intensity of the pain decreased slightly. Imaging studies (MRI and CT) ruled out any intracranial pathology but showed possible abnormal cervical rotation at the C2 level. The MRI further confirmed a compression of the dorsal roots of C1/C2 and a possible compression of C3. Based on the current literature, clinical findings in this case strongly suggested an uncommon presentation of TAC, but the patient did not respond to indomethacin trial (prescribed as 50 mg OD to start; titrated up to 150 mg per day in divided doses, over two weeks as much as the patient could tolerate) or to oxygen therapy. However, a trial with lamotrigine slightly improved the severity of the attacks. The patient was seen by a psychiatrist who prescribed tricyclic antidepressants, which were ineffective. The only medication that the patient responded to, and had 90% of pain relief, was with intramuscular (IM) tramadol prescribed by a pain management specialist. His diagnosis for the same was “idiopathic facial neuralgia.” We had focused our clinical examination on the reproduction of pain. The pain was finally successfully reproduced by hyperextending the patient's neck and concomitant firm palpation of the suboccipital area. Upon this maneuver, the pain was triggered from the back of the neck (C2, C3 distribution) and spread to supraorbital, periorbital, and retro-orbital locations (trigeminal distribution). Once the pain was triggered, the most intense pain (nine to ten out of ten) was in the trigeminal distribution. The diagnostic test performed was greater/lesser occipital nerve block, which aborted the attack [Figure 2]. The immediate treatment was the IM tramadol injection 50 mg. (previously prescribed) TID to alleviate the symptoms. This was followed by hypermobility exercises by a board-certified physical therapist well-versed in hypermobility syndromes. Regular hypermobility exercises reduced the severity and frequency of the attacks. Intermittent attacks were aborted with occipital nerve blocks, as they would occur. At 1-year follow-up, the patient was completely pain-free with no residual pain.
Definition and classification
ON is a neuropathic pain arising from the lesser, greater, and/or third occipital nerves. The National Institute of Health (NIH) describes ON as “a distinct type of headache characterized by piercing, throbbing, or electric-shock-like chronic pain in the upper neck, back of the head, and behind the ears, usually on one side of the head”. With regards to the International Association for the Study of Pain (IASP), the 2002 taxonomy/classification of chronic pain had distinct definition of ON, but was removed in the 2019 classification.
Arnold's neuralgia, Benito's neuralgia (first description), C2/C3 neuralgia, greater and lesser ON.
Sometimes, ON occurs secondary to nerve entrapment in the semispinalis capitis muscle, splenius muscle, or the trapezius muscle or the fascia [Figure 2]. Some literature indicates that the etiology of ON could be due to irritation of C2/C3 by spasm of muscles or upper cervical spine spondylosis.,, The vascular causes described in the literature as etiology include, but not limited to irritation of C2/C3 by an artery; arteriovenous fistula; hemangioma; and giant cell arteritis.,,, The neurogenic etiology of ON that shows up in the literature, includes schwannoma of the occipital nerve, myelitis, and multiple sclerosis. The osteogenic etiology appearing in the literature includes osteosclerosis, hypermobility, and bone destroying lesions.
Very few studies have reported the prevalence and incidence of ON and they mainly focus on specific populations. However, some smaller studies have reported that ON represents approximately 4% of all cranial neuralgias. In a study of Spanish elderly patients, ON was reported to be of the highest frequency amongst cranial neuralgias. A study done in Holland showed an approximate prevalence of 3/100,000 in the general population. The same study reports the mean age of diagnosis as approximately 54 years. Although some literature points out that the incidence of ON does not have gender predilection, multiple studies have shown a female predilection for ON.,,,, In a given population the incidence of ON has been reported as 8% of all craniofacial pain cases., Recent case series study has shown the time elapsed from symptom onset to diagnosis as approximately 25–50 months.
Onset: Onset of ON is usually described in the literature as sudden/acute.,
Location: Location of ON pain is classically described as back of neck, head (occipital), and spreading to the vertex. With regards to side predilection, the left side was found to be more prone to ON compared to the right side. It is interesting to note that this side predilection is contrary to that in other more common entities such as trigeminal neuralgia, where the reported predilection is for the right side of the face.,, The proposed mechanism according to these authors is the “relative narrowing of foramina through which the trigeminal nerve branches exit”. Also, the hypothesized mechanism for the left-sided predilection of ON, was the sleep posture, with a left lateral recumbency., Approximately in one-third of the cases, bilateral pain was reported.
Chronicity: ON is usually described as chronic, more likely due to the lag between the onset of symptoms and the diagnosis.
Frequency: Some authors describe the frequency as continuous (when remission was absent), remitting (pain-free periods exceeding a month), and undefined (pain not lasting more than 3 months since its onset). The frequency of involvement of GON as opposed to LON in the causation of ON is estimated to be 9:1.,
Duration: A continuous type of background/baseline pain of lower intensity with occasional exacerbations of higher intensity has been reported by some authors. The duration of the exacerbated pain is described as few seconds to a few minutes (ICHD-3).
Intensity: The baseline pain is reported to have an approximate average intensity of 5.5, and that of exacerbated pain to be 8 on a VAS scale (on 0–10 VAS scale).
Quality: Quality of ON exacerbations is variably reported as stabbing, lancinating, oppressive, burning, and/or throbbing, in the descending order of incidence. Quality of baseline/background pain is described as oppressive, stabbing, burning, and throbbing in the descending order of incidence. Quality of sensitive disorders of ON is described in the same article as “allodynia and hypoesthesia”.
Temporal Pattern: A change in the characteristics of ON pain has not been reported except for remissions, as alluded to earlier.
Aggravating Factors: Aggravating factors/triggers for ON include abnormal neck posture/neck movements, spasms of the trapezius and sternocleidomastoid muscles.
Relieving Factors: Relieving factors include rest, nerve blocks, physical therapy, medications, and surgical management.
Response to Past Treatments: The patient with ON may report either no benefit or partial benefit from such past management modalities as medications.
Associated Features: The usual associated features are allodynia, dysesthesia, pressure sensitivity, and tenderness to palpation on the greater or lesser occipital nerve course. Also reported are tinnitus, nausea, dizziness, and visual disturbances.
Radiation/Referral: Radiation of the pain in ON is described as originating in the occiput and radiating to the vertex.
Sleep Relation: No robust association between ON and sleep (including sleep-related quality of life) was found in the literature. Certain articles talk about ON having no effect on sleep-related quality of life.
Diagnostic testing for ON, includes physical exam (reproduction of the pain in the distribution of the nerve); diagnostic block of the nerve; ultrasound (helps nerve block); MRI (for identification of a lesion); radiography (possibly showing C2/C3 arthropathy).
There is considerable overlap in the clinical presentation of ON and primary headaches. The main differential diagnoses include migraine, cluster headache, hemicrania continua, tension-type headache, and giant cell arteritis, The other less common differential diagnoses include postherpetic neuralgia, cervicogenic headache, and secondary causes for ON.
Identification and management of perpetuating factors are crucial in the treatment of ON. Some articles propose conservative methods of management including rest, on and off warm/cold compresses, massage therapy, and physical therapy, as initial treatment. Pharmacotherapy includes a variety of classes of drugs, including anti-inflammatory, muscle relaxants, anti-seizure and anti-depressants. These drugs reportedly have varied efficacies. As alluded to in our case report, an anesthetic blockade of C2/C3 helped in pain relief and confirmed the diagnosis of ON. The nerve blocks employed in the management of ON, include ultrasound-guided, fluoroscopy-guided, and landmark guided. Some authors recommend the use of injectable corticosteroids along with local anesthetic. Interestingly, C3 stimulation has also been successfully used for management of ON.,,, Considerable pain relief has also been reported by the use of Botulinum Toxin-A., Pulsed radiofrequency has been used for neuromodulation in refractory ON.,, Surgical techniques used in the management of ON include, cryoneuroablation,, neurectomy, peripheral nerve stimulation,, and neurolytic injections.
Some authors have described achieving approximately 6 months of good pain relief with anesthetic blockade. With appropriate elimination of the differential diagnosis and succinct treatment, ON has a fair to good prognosis, especially with the use of anesthetic blockage, and techniques like pulsed radiofrequency, and neuromodulation.
Case discussion in the context of the literature
The patient's presentation of “sudden onset” is consistent with some of the published literature.
The chances of irritation to the nerve and entrapment may be higher with joint hypermobility. Taking a comprehensive and accurate history is the first step to achieving a proper diagnosis, potentially leading to management success. In this particular case, the peculiar presentation confused most medical specialists the patient had consulted. This can also be due to the lack of quality time spent with the patient, which is the first and most important component to achieve a proper diagnosis.
Furthermore, different patients can present with a varied range of symptomatology for the same condition. This peculiar case did not follow any textbook description. Although the pain location was consistent with what the ICHD-3 describes, the elicitation of the pain provoked by palpation of the suboccipital area, and the fact that the only medication to help subside the pain was IM tramadol, which makes this case extremely unique.
The patient reported reproduction of familiar pain with digital pressure applied by the clinician to the insertion of the suboccipital, trapezius, semispinalis capitis, and splenius capitis muscles. An anesthetic block of the GON relieved the pain. This can be explained based on nerve entrapment within the muscle fibers, which has been described as a possible cause of ON. This patient's pain pattern could be explained based on convergence and possible anastomosis between branches of the trigeminal nerve and C2/C3 nerves. The GON has been shown to widen its distribution as it approximates the periphery through its terminal branches. The relevance of this observation in the causation of ON has been reported. This would explain the symptoms the patient had in the distribution of the terminal branches of the trigeminal nerve, along with the distribution of C2/C3. The functional and anatomical convergence of the trigeminal nerve and C2/C3 is evident in the recently published literature. Activation of the trigeminal nerve branches has been shown to induce symptoms in the cervical nerve territory and vice versa. This phenomenon has been traditionally explained in the literature by the convergence of multimodal fibers from these nerves.
IM tramadol was the only medication capable of relieving the symptoms in this case. Recent publications have alluded that tramadol is not primarily a medication for neuropathic pain. However, clinical and animal basic research has shown tramadol's efficacy in neuropathic pain cases/models. The traditional pharmacological explanation for this efficacy is based on the fact that tramadol has μ-opioid agonist and weak serotonin-norepinephrine reuptake inhibitor-like action.
ON secondary to nerve entrapment is a significant diagnostic dilemma for the clinician. A careful history, examination, and provocation of the patient's familiar pain are essential keys to the diagnosis of this entity. It is crucial to reassess the patient, if there is no response to conventional therapy.
We acknowledge all the six authors consistent with what was mentioned above in contributions.
Financial support and sponsorship
The authors received no financial support and are not currently in receipt of any research funding for the research, authorship, and/or publication of this article.
Conflicts of interest
The authors declared no potential conflicting interests with respect to the research authorship and/or publication of this article.
[Figure 1], [Figure 2]