|Year : 2020 | Volume
| Issue : 3 | Page : 212-214
Greater occipital nerve block- A case report of a patient of Occipital neuralgia using proximal approach under USG guidance
Vikas Tyagi, Dhruv Bibra, GP Dureja
Delhi Pain Management Center, New Delhi, India
|Date of Submission||23-Jan-2020|
|Date of Decision||12-Mar-2020|
|Date of Acceptance||23-Sep-2020|
|Date of Web Publication||28-Dec-2020|
Dr. Vikas Tyagi
H-2/10, Shiksha Apartment, Sector-6, Vasundhra, Ghaziabad - 201 012, Uttar Pradesh
Source of Support: None, Conflict of Interest: None
Occipital neuralgia is a neuropathic pain disorder with distinctive diagnostic and therapeutic challenges. Many pain physicians and neurologists consider this to be a nonexistent condition which merely represents a variant of cervicogenic headache emanating from C1 to C4 nerve roots. Repetitive microtrauma from a hyperextended neck (painting ceilings or working with computers for long hours with a high focal point) may result in the development of this condition. Failure of conservative management necessitates greater occipital nerve (GON) block in the treatment of occipital neuralgia. Conventionally, GON has been blocked at superior nuchal line through a landmark-guided technique using occipital artery pulsations as guidance or using ultrasound as done in classical distal technique at the same site. Another less frequently used technique under ultrasound is the one where the nerve is blocked at a proximal site. We describe here a case report where we chose proximal technique done under ultrasound, superficial to the obliquus capitis inferior muscle (OCIM), which has a higher success rate and allows for a more precise blockade of the nerve before it branches out as in distal technique.
Keywords: Greater occipital nerve, obliquus capitis inferior muscle, occipital neuralgia, ultrasound guidance
|How to cite this article:|
Tyagi V, Bibra D, Dureja G P. Greater occipital nerve block- A case report of a patient of Occipital neuralgia using proximal approach under USG guidance. Indian J Pain 2020;34:212-4
|How to cite this URL:|
Tyagi V, Bibra D, Dureja G P. Greater occipital nerve block- A case report of a patient of Occipital neuralgia using proximal approach under USG guidance. Indian J Pain [serial online] 2020 [cited 2021 Apr 12];34:212-4. Available from: https://www.indianjpain.org/text.asp?2020/34/3/212/305134
| Introduction|| |
Occipital neuralgia has been defined as unilateral or bilateral paroxysmal, shooting pain in the posterior part of the scalp, in the distribution of the greater or lesser occipital nerves, commonly associated with tenderness over the involved nerve. It is usually made worse with the movements of the neck. The greater occipital nerve (GON), which derives most of its fibers from the C2 dorsal root, is the main sensory nerve of the occipital area.
There is no specific test to diagnose occipital neuralgia. History, physical findings (i.e., tenderness over the occipital nerves), and improvement in the headache with a local anesthetic block of the occipital nerve on the affected side confirm the diagnosis. X-ray of cervical region is used to rule out cervical spondylitis. Magnetic resonance imaging (MRI) brain is required to rule out any occult pathology (Arnold–Chiari malformations, tumors). Once a provisional diagnosis of occipital neuralgia has been made, treatment is started with nonsteroidal anti-inflammatory drugs, tricyclic antidepressants, muscle relaxants, physical therapy, or neural blockade with local anesthetic and steroid. Neural blockade of the GON (which is the main sensory nerve of the area) serves both as a diagnostic as well as a therapeutic maneuver.
For many years, GON has been blocked through a landmark technique using occipital artery pulsations as reference, but of late ultrasound-guided blocks are gaining popularity. Ultrasound-guided blocks have been traditionally done by a classical distal approach where the nerve is blocked at the level of superior nuchal line. We describe here a case report using a proximal approach at C2 level, which has more chances of a successful block compared to the classical ultrasound-guided technique due to a more constant relationship of the GON to the obliquus capitis inferior muscle (OCIM) at this level.
| Case Report|| |
A 32-year-old male presented to our outpatient department with sharp pain in the posterior scalp more on the left side for over 6 years. Pain was sharp and shooting with a frequency of 4–5 times/day. Pain would travel up to the vertex, especially with the lateral bending of the head.
The patient did not give any history of trauma to the cervical spine or head, but his job involved sitting for long hours before computers. The medical history was unremarkable, and there was no significant family history. His routine laboratory investigations were normal except mild deficiency of Vitamin D3, which was treated with oral cholecalciferol. X-ray cervical region and MRI brain were also normal.
On detailed physical examination, no sensory deficit was observed in the occipital region. The patient had marked tenderness (left > right) near the medial portion of superior nuchal lines. His baseline numerical rating score (NRS) was 9/10 during exacerbations.
The patient had received anticonvulsants (gabapentin and carbamazepine), tricyclic antidepressants (nortriptyline), opioids (tramadol), muscle relaxants (tizanidine), and nonsteroidal anti-inflammatory drugs (NSAIDs) (diclofenac and etoricoxib) in usual doses with no relief. He also reported no relief with extensive physiotherapy sessions. The patient also exercised for many months including morning walks and neck exercises. Unfortunately, none of these interventions could bring him any relief. The patient had stopped all medications for the past 6 months.
Based on the clinical history and detailed physical examination and having reviewed laboratory and radiological investigations, we made a provisional diagnosis of occipital neuralgia. Since the patient had exhausted medical management, we decided to perform a diagnostic greater occipital block with ultrasound guidance through the proximal approach.
An informed consent for the procedure, explaining the side effects and expected duration of relief with a possibility of repeating the block also, was taken. Procedure was performed inside the operation theater with monitoring of vital signs with standard monitors.
The patient was asked to sit on a stool with his forehead resting on a padded bedside table. A high frequency (10–12 MHz) linear transducer was placed with the initial position of the probe being at external occipital protuberance in a transverse plane [Figure 1].
|Figure 1: External occipital protuberance in transverse view under ultrasound|
Click here to view
Now, slowly transducer was moved caudally to identify atlas vertebra [Figure 2].
We continued to go caudally till C2 level and then moved the probe laterally with the medial end of the transducer pointing toward the bifid spinous process of the axis and the lateral end pointing toward the transverse process of the atlas (the GON is the posterior ramus of C2 and emerges below the posterior arch of the atlas. It curls around the lower border of the OCIM and passes cranially superficial to this muscle across the roof of the suboccipital triangle).
Moving the transduce further laterally first a boat-shaped muscle, OCIM was identified and moving a little further laterally along the width of the OCIM, an oval-shaped hypoechoic structure was identified which was GON [Figure 3] (GON travels in a fascial plane between the OCIM and the semispinalis capitis muscle (SsCM) as it ascends on the posterior surface of the OCIM before it pierces (SsCM). The GON terminates as a superficial nerve by either piercing the upper part of the trapezius muscle or running through the tendinous arch between the trapezius muscle and the sternocleidomastoid muscle, where it lies medial to the occipital artery).
Now, a 22G, 5 cm needle was introduced from lateral to medial direction to target the nerve in a fascial plane between semispinalis capitis and OCIM. Using Doppler, we ruled out any vascular structure in the targeted path of the needle. Finally, 4 ml of 0.25% bupivacaine with 20 mg of methylprednisolone was injected under live ultrasound guidance around the nerve after negative aspiration of blood. Drug spread was confirmed with ultrasound. Once the procedure was over, the patient was monitored for 15 min in the operation theater.
Postprocedure, the patient was again monitored for 45 min in the postoperative unit. Patient's NRS score immediately came down to 2/10. The patient did not report any postprocedure complications except some mild needle-induced pain, for which a 5-day course of NSAID was given. The patient was called for follow-up after 2 weeks, and he reported 90% relief in pain. After 6 weeks, the patient was completely pain free.
| Discussion|| |
Occipital neuralgia is an infrequent cause of headache characterized by pain in the distribution of the greater or lesser occipital nerves, which innervate the posterior scalp (greater in 90% and lesser in 10%). There is no specific test to diagnose occipital neuralgia, and diagnosis is made on clinical history in tandem with physical examination findings such as a marked tenderness over the distribution of the GON. MRI of the brain is required to rule out any occult pathology.
Management of occipital neuralgia involves pharmacotherapy (anticonvulsants, tricyclic antidepressants, and NSAIDs), neck exercises, and physiotherapy. Nerve block to this region is easy due to the superficial nature of the nerves. The International Classification of Headache Disorder-3 lists occipital neuralgia as the only condition in head-and-neck pain where nerve block should be used as first-line treatment ahead of pharmacotherapy.
Both landmark- and ultrasound-guided approaches have been described for GON block. The ability of ultrasound to guide the needle and observe the spread of local anesthetic can be invaluable to avoid complications, such as inadvertent intraarterial injection, compared to the landmark technique. Furthermore, anatomic variations in some patients result in the GON occasionally being located lateral to the occipital artery. For this reason, larger amounts of local anesthetic (10–12 ml) are generally used to increase the chance of blocking the GON.
We preferred the proximal ultrasound approach over the distal ultrasound approach due to the constant and reliable relationship of the GON to the OCIM. The first part of the course of the GON is closely related to the OCIM, which connects the spinous process of C2 with the transverse process of C1. More distally, the GON divides in many branches and courses through the SsCM, finally piercing this and the trapezius muscles' aponeurosis at variable locations. The marked variability and multiple branching of the GON at the classical block site are the reason why the success rate of the classical technique is 80%, while the proximal technique has 100% success as shown in cadaveric studies.
After a successful diagnostic block, pulsed radiofrequency ablation and occipital nerve stimulation may also be used to prolong relief in selected patients.
| Conclusion|| |
The proximal approach to block GON under ultrasound guidance at C2 level, though less commonly used, has more chances of success compared to other approaches. Although this technique is there in literature, yet it is not very commonly performed by clinicians in India. We believe that, in the near future, it would become the standard for GON block as more and more pain physicians incorporate this in their practice.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]