Atypical refractory occipital neuralgia treated with a unilateral dual-lead occipital nerve stimulator: a case report

Abstract

Aim: To describe the successful treatment of atypical occipital neuralgia (ON) using a unilateral dual-lead occipital nerve stimulator.

Setting: Outpatient clinic/operating room.

Patient: A 53-year-old male with atypical ON.

Case description: Patient was previously diagnosed with treatment-refractory left-sided trigeminal neuralgia with atypical occipital distribution. On presentation, his symptoms were consistent with ON with distribution to the left fronto-orbital area. He received a left-sided nerve stimulator implant targeting both the greater and lesser occipital nerves.

Results: Patient reported pain relief from a numerical rating scale 10/10 to 3-4/10.

Conclusion: ON with referred ipsilateral trigeminal distribution should be considered when patients present with simultaneous facial and occipital pain. Further, a dual-lead unilateral stimulator approach may be a viable treatment.

Plain Language Summary

Atypical, persistent inflammation to the left occipital nerve treated with a neuromodulator: a case report

Aim: To describe the successful treatment of atypical headache using a one-sided nerve stimulator.

Setting: Outpatient clinic/operating room.

Patient: A 53-year-old male with atypical headache.

Case description: Patient was previously diagnosed with left-sided chronic facial pain with pain to the back of the head. He previously failed to improve with medication and underwent Botox injections and several surgical operations targeting the nerves responsible for his pain symptoms with no improvement. He recently underwent a nerve-stimulating device trial, designed to alter the activity levels of the targeted nerve, that targeted a nerve in the back of his head. This significantly improved his pain and he ultimately presented for an official stimulator implant. Upon presentation, his symptoms were consistent with left-sided headache to the back of the head with distribution to the left eye area.

Results: Patient reported significant pain relief from 10/10 to a 3-4/10, with a 10 representing the worst pain the patient has ever felt.

Conclusion: Left-sided headache on the back of the head that can distribute to the left eye area should be a consistent thought for pain/headache practitioners. Further, this stimulator placement approach may be a viable treatment.

Plain language summary

Article highlights.

• Patient presented with chronic left-sided headache with radiation to the fronto-orbital and occiptal regions that were characterized to be initially intermittent and progressed into persistent pain.

• Patient was refractory to multiple pharmacological and procedural interventions, including occipital nerve decompression and a series of three radiofrequency ablations.

• On current presentation, the team concluded with a diagnosis of occipital neuralgia with radiating pain to the left fronto-orbital area likely due to the connections in the trigeminocervical area.

• A dual-lead nerve stimulator was inserted using a medial approach with incision at the level of C1-2, targeting both the greater occipital nerve (GON) and lesser occipital nerve of the left side.

• Occipital neuralgia (ON) is a condition in which the occipital nerves (GON, lesser and third occipital nerves) that run through the scalp are injured or inflamed due to trauma, muscle tension, inflammation or structural abnormalities in the cervical spine.

• This may cause severe sharp, piercing, throbbing or shocking pain in the upper neck, posterior scalp or auriculotemporal areas.

• The GON originates from the medial branch of the dorsal rami of the C2 nerve root and is the main afferent sensory signal through the C2 root. It is directly sent to the C2 dorsal horn.

• There are also second-order neurons in the trigeminocervical complex of the C2 dorsal horn receive convergent inputs from facial skin correlated with the dural and cervical structures innervated by the C1-3 nerve roots.

• Treatments can include conservative measures (pharmacotherapy, physical therapy), nerve blocks/ablations, decompression surgery, stimulator and peripheral nerve surgery.

• This case report suggests there could be an anatomical and physiological relationship between GON irritation due to constant afferent input of ON and hypersensitivity with the neurons of the trigeminocervical complex.

• A unilateral dual lead approach to more specifically target the referred trigeminal distribution of atypical ON may be a promising solution.

• There is a lack of robust studies regarding the unilateral dual lead approach for atypical ON and other headache pathologies. As such, further research is needed to delineate its uses.

1. Case

1.1. Case presentation

A 53-year-old male presented with a 3-year history of left-sided headache and pain. Pain was described to be localized to the fronto-orbital and occipital areas, with radiating pain in between these points. He described the pain initially as intermittent, throbbing, sharp, stabbing, ‘electric-like’ and shooting. The pain was exacerbated with mastication, increased sinus pressure and breathing. The pain was not noted to correlate with the timing of the day and slowly progressed to constant pain throughout the third year since onset. He described it as a 9–10/10 on the numeric rating scale (NRS). He previously failed pharmacological treatments including gabapentin, pregabalin, nortriptyline, duloxetine, phenytoin, carbamazepine, prednisone and ubrogepant. Due to treatment-refractory pain, he underwent occipital nerve decompression surgery, multiple onabotulinumtoxinA injections and radiofrequency ablation in July 2022, October 2022 and January 2023, respectively, with no improvement. He recently underwent an occipital nerve stimulator trial that improved his prior 10/10 pain to 3-4/10 and was eager to proceed with a permanent nerve stimulator implant. The initial working differential included unilateral facial pain of unclear etiology, atypical trigeminal neuralgia (TN) and occipital neuralgia (ON).

The rest of patient medical history was non-contributory.

1.2. Initial diagnosis/assessment

On physical examination, the patient had distinct, severe tenderness to palpation on the left suboccipital and supraorbital region. The patient verbally mentioned constant burning pain in the upper neck, suboccipital and supraorbital regions as well. Range of motion of the cervical spine was within normal limits. The patient could open his jaw slowly but was limited by pain. The NRS was a 10/10 consistently. His cranial nerves were intact with no focal neurological deficits. Per the International Classification of Headache Disorders, version 3 (ICHD-3), the patient met criteria for both ON and TN [1,2]. Given the initial intensity of the patient’s pain in the left facial area, he was previously diagnosed with TN with unclear pain in the occipital area. However, the ICHD-3 specifically mentions that “the pain of ON may reach the fronto-orbital area through trigeminocervical interneuronal connections in the trigeminal spinal nuclei” whereas ICHD-3 diagnostic criteria for TN does not mention any such radiation/connection from TN as the primary etiology with radiation to the ON [1,2]. Thus, when seen in office, the team assessed and diagnosed his symptoms as ON with radiating pain to the left fronto-orbital area likely due to the connections in the trigeminocervical area.

1.3. Surgical procedure

The patient opted to undergo a left-sided occipital nerve stimulator implant. The universal protocol was performed and informed consent was obtained; options, risk and benefits were discussed and the patient desired to proceed. Battery site location was marked with assistance of the patient. The surgical procedure was completed under general anesthesia care using midazolam, fentanyl and propofol infusion with intermittent boluses. Patient was positioned prone supported with pillows and padding under the abdominal frame, feet and pressure points. Patient was prepped and draped appropriately in a sterile fashion. Skeletal landmarks were marked with fluoroscopy guidance.

The surgery was carried with an incision at the posterior scalp C1-2 level. Skin incisions and subcutaneous pockets were created with blunt and Bovie dissection. A Tuohy needle was advanced from the posterior scalp incision to contact the skull and then advanced left laterally at the base of the posterior skull. Two leads were ultimately placed in the locations of the left greater occipital nerve (GON) and lesser occipital nerve (LON). An eight-pole stimulator (Medtronic, MN, USA) lead was then used to target these. The second lead was placed in a similar fashion to enter around the L1-2 level. The final position of the LEFT lead was left of midline, with the top contact at T8 level. To clarify, the patient did not undergo simultaneous spinal cord stimulator insertion. The leads were then anchored. Reexamination showed proper placement and no additional movement. Lead placement is demonstrated in Figure 1.

Figure 1.

Anteroposterior x-ray image of the dual-lead placement targeting the left greater occipital nerve and left lesser occipital nerve.

A generator pocket was created at the mid-back below the ribs. The leads were tunneled through the subcutaneous tissue and connected with the generator and tightened. The generator was placed in the pocket with excess coiled lead beneath it. Relief loops were placed in the paramedian spinal incision. Testing of the leads and generator revealed appropriate functioning and impedances.

Results were primarily measured using the percent reduction in pain using the NRS. Additionally, the team informally assessed overall patient satisfaction, demeanor/attitude and resumption of activities of daily living and baseline function during the various appointments.

1.4. Postoperative outcome

Upon postoperative day 5, patient presented for wound check where incision sites were clear, dry and intact with no signs of erythema or edema. Upon postoperative day 10, the patient presented for removal of staples and turning on the stimulator. At his 4-week follow-up, he presented for incision check and follow-up and pain assessment using the NRS. At his 6-week follow-up, he presented for physical restriction reevaluation. Stimulation variables used for the occipital nerve stimulation (ONS) are similar to those used for spinal cord stimulation. The intensity current ranged from 2–4 mA and was ultimately set at 2.4 mA. Follow-ups with the patient (1 month, 3 months) showed significant improvement to 3-4/10 from 10/10, as reflected in the NRS.

2. Discussion/conclusion

ON is defined by the American Association of Neurological Surgeons as a condition in which the occipital nerves that run through the scalp are injured or inflamed. This could be due to trauma, muscle tension, inflammation or structural abnormalities in the cervical spine. This may cause severe sharp, piercing, throbbing or shocking pain in the upper neck, posterior scalp or auriculotemporal areas.

Typically, ON involves the GON, LON and third occipital nerve [3,4]. There have been extremely rare instances where ON may extend to the trigeminal V1 distribution due to the connections between the trigeminocervical connection in the trigeminal spinal nuclei [3]. GON entrapment has also recently been found to possibly cause referred pain to the trigeminal nerve distribution of all three branches (V1, V2, V3) [3].

The management of ON aims to alleviate pain, improve functionality and enhance overall well-being. Treatment options range from conservative measures to interventional pain treatments. Conservative treatments include rest, heat therapy, physical therapy, lifestyle modifications, stress management and first-line pharmacological therapies such as tricyclic antidepressants, serotonin reuptake inhibitors and anticonvulsants (such as gabapentin and pregabalin) [4]. If conservative therapies are ineffective, nerve blocks and ablation treatments like pulsed radiofrequency, thermal radiofrequency and cryoablation may be considered [4,5].

If these do not work, various stimulators can be used. These can include ONS via percutaneous or surgically implanted epidural leads and percutaneous peripheral nerve stimulation [6–8]. Key differences between these approaches lie in the site of electrode placement and the invasiveness of the procedures. Percutaneous or surgically implanted epidural leads target the occipital nerves within the epidural space, while percutaneous peripheral nerve stimulation directly stimulates the peripheral nerves involved in ON. Lastly, if all else fails, nerve surgery and nerve damage repair can be utilized [4,9–11].

This is the first case to the best of our knowledge of refractory ON with referred supraorbital pain that was treated with an occipital nerve stimulator utilizing a unilateral dual lead stimulator approach.

2.1. Referred ipsilateral trigeminal pain from atypical ON

The primary etiology of ON is not clearly delineated. Entrapment of the GON is one of the common causes that has been found [4,12]. However, any GON pathology such as infection, inflammation or irritation could theoretically lead to this issue [12,13]. This is elucidated through the anatomical path. The GON originates from the medial branch of the dorsal rami of the C2 nerve root [14]. Thus, it is the main afferent sensory signal through the C2 root. It is directly sent to the C2 dorsal horn. Further, there are also second-order neurons specifically in the trigeminocervical complex (TCC); these are a host of neurons in the C2 dorsal horn that receive convergent inputs from facial skin correlated with the dural and cervical structures innervated by the C1-3 nerve roots [15]. As such, there could be an anatomical and physiological relationship between the GON irritation due to constant afferent input of the ON and hypersensitivity with the neurons of the TCC. There have been reports on patients with primary headaches who have pain involving both the frontal head innervated by the trigeminal nerve and the occipital region innervated by the GON. This is commonly seen in patients with chronic migraine, especially when untreated or uncontrolled. ON blocks are often used to treat chronic migraine by modulating TCC activity and downregulating trigeminal circuitry. These blocks are also commonly employed in the treatment of other primary headache disorders including but not limited to trigeminal autonomic cephalalgias namely cluster headache. The neuromodulation of the TCC may have thus provided benefit to this patient.

One case by Son describes referred trigeminal V2, V3 facial pain from ON in which the patient had an intermittent, 4-year history of severe paroxysmal pain in the left preauricular temporal region, later simultaneously spreading to the left vertex, retroauricular occipital region and deep in the left ear [16]. Son hypothesized symptom etiology to be due to GON entrapment leading to referred pain to the auriculotemporal nerve, the terminal branch of the mandibular nerve (V3 region), since GON decompression led to symptomatic relief when blocks around the auriculotemporal nerve did not [16].

A second case report by Lee and colleagues detailed a patient with an intermittent, 10-year history of stabbing pain in the left retroauricular suboccipital pain, later presenting with 5-month history of left-sided facial burning pain and tingling sensation, extending from the left malar and periorbital area to left upper lip [17]. Here, the patient’s symptoms were found to be referred hemifacial pain to the ipsilateral V1 and V2 distribution from chronic ON.

Noh and colleagues documented a similar case report in which a patient presented with an 8-year history of left temporo-occipital headache and facial stinging and stabbing pain initially preceded with dull pain to the back of the neck [18]. The patient was originally diagnosed with chronic migraine, but eventually a GON decompression led to symptom relief.

This literature (in addition to more) demonstrates cases of ON caused by compression of the GON by the occipital artery within the trapezial tunnel. This ultimately leads to referred pain to various patterns of trigeminal innervation. All three cases were refractory to medication prior to surgical decompression which led to successful symptom management [16–18]. However, the case described above was refractory to both medication and surgical decompression. Cases reported by Lee and colleagues and Noh and colleagues show clinical history in which ON preceded trigeminal nerve involvement [17,18]. However, Son details the reverse symptom course, similar to the case described above where symptoms of TN preceded ON symptoms [16].

2.2. Unilateral dual leads ON stimulator approach

Typically, an occipital nerve stimulator (ONS) for bilateral ON has bilateral lead placements at C1 with trajectories ranging from zero degrees (straight lateral) to almost 90 degrees toward the vertex of the occipital scalp [6,19]. For unilateral occipital neuralgia, there would typically be one lead placement ipsilateral to the side of symptoms (i.e. left-sided ON has one left sided-lead, right-sided ON has one right-sided lead, bilateral ON has two leads where one is targeted toward the left side and one toward the right side) [20]. Once leads are positioned, the patient would be awakened for the intraoperative stimulation trial to confirm coverage in the painful occipital area [21]. Once confirmed by the patient, leads are anchored to the position subcutaneously.

In this case, these two leads more specifically targeted the greater occipital and lesser occipital nerves rather than using one lead and targeting the overall general occipital nerve area [20]. This allows for a more pinpoint approach to the GON to incorporate the trigeminal distribution whereas the typical single-lead approach does not allow for a pinpoint approach. This approach may be another viable option for patients who require targeted and additional relief for severe refractory unilateral ON.

Liu and colleagues describe a patient with diagnosed right ON which later progressed to bilateral ON after pharmacological treatment [22]. Here, they performed a percutaneous unilateral, single-lead ONS, approached from the right to the left, perpendicular to the bilateral occipital nerve course at the level of C1 [22]. An external generator was implanted subcutaneously in the upper right chest area after a 7-day trial stimulation [22]. Venico and colleagues reported a patient with a 5-year history of refractory ON who underwent surgical unilateral single-lead ONS [23]. Here, a right paramedian incision was performed at the level of C1 and the lead was inserted and directed laterally toward the right mastoid region and the external generator was placed subcutaneously in the infraclavicular region [23].

Similarly, Moman and colleagues also reported a case in which the patient presented with a 6-year history of chronic right-sided head pain secondary to head trauma originating in the right suboccipital region. This pain radiated to the vertex region. Pain was refractory to pharmacological interventions and nerve blocks [24]. The patient underwent a percutaneous unilateral single-lead ONS targeting the right GON at the level of C2 with a medial to lateral approach [24]. The external generator was secured subcutaneously in the lateral border of the right trapezius [24].

These studies ultimately described persistent symptom relief after undergoing either percutaneous or surgical ONS [22–24]. In these cases, only the GON was targeted with a single lead, while the case described above employed a dual-lead approach that targeted the GON and the LON [22–24]. In the cases with diagnosed isolated unilateral ON, a medial to lateral lead placement approach was applied, including the case described above [23,24].

ONS is a promising solution for various headache disorders such as classic ON. As research continues regarding its effects on other headache pathologies, an ipsilateral dual-lead ON stimulator approach could provide an alternative surgical option for atypical headache pathologies such as referred ipsilateral pain from ON. Further robust studies are needed to validate its uses and enhance the evolving field of nerve stimulation and neuromodulation.

Author contributions

D Wang and A Turabi gave the concept and the design. D Wang, C Li and A Turabi performed the acquisition, analysis and interpretation of data. D Wang, C Li and A Turabi performed critical revisions of the manuscript for important intellectual content. D Wang provided administrative, technical or material support. D Wang performed supervision.

Financial disclosure

The authors have no relevant financial support or affiliations with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes but is not limited to grants, funding for writing assistance, personal academic/financial relationships, intellectual property, etc.

Competing interests disclosure

The authors have no relevant competing interests/conflict of interests with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes but is not limited to unpaid memberships in a government/non-governmental organization; advocacy or lobbying organization; advisory position in a commercial organization; writing or consulting for an educational company; and expert witness roles.

Ethical conduct of research

The authors state that a case report is a medical/educational activity that does not meet the Department of Health and Human Services definition of ‘research’, which is “a systematic investigation, including research development, testing and evaluation, designed to develop or contribute to generalizable knowledge”. Therefore, the activity does not need institutional review board approval by MedStar Health policy. In addition, informed verbal consent was obtained from the patient for the inclusion of their medical and treatment history for this case report while remaining anonymous.