Article topic: Occipital Neuralgia
Name of the author: Rana Jaffal
Name of the editors: Rawan Hamamreh, Mohammad Assaf
Reviewer: Ethar Hazaimeh
Keywords: Headache, Neuralgia, Neck Pain, Neuropathic pain, Occipital
Overview
Neuralgia is defined by The International Classification of Headache Disorders ICHD-3 as “pain in the distribution(s) of a nerve or nerves, presumed to be due to dysfunction or injury to those neural structures. Common usage implies a paroxysmal pain quality as neuralgia, but the term neuralgia should not be reserved for paroxysmal pains”. The most common neuralgias are trigeminal neuralgia, occipital neuralgia, glossopharyngeal neuralgia, and nervus intermedius neuralgia.1.2
Occipital neuralgia (ON), as defined by the International Headache Society, “is a headache characterized by piercing, electric-shock-like, or throbbing chronic pain in the upper neck, back of the head, and behind the ears. Usually, it is unilateral. In most cases, the pain of occipital neuralgia begins in the neck and then goes upwards, the pain could be in the scalp, forehead, and behind the eyes. The location of the pain is related to the parts supplied by the lesser and greater occipital nerves, which are run from the area where the spinal column meets the neck, up to the scalp at the back of the head”. 3
Epidemiology
ON is a well-known disorder, but its incidence remains not accurately determined. As mentioned in a study that investigated the incidence of facial pain in a Dutch population, ON comprised 8.3% of facial pain cases. The total incidence of ON was 3.2 per 100,000 people, with a mean age of diagnosis of 54.1 years (standard deviation of 16.2 years), female dominance was present but not significant, and no time and seasonal variations were found.4
Pathogenesis and etiology
Figure (1): Anatomy of occipital nerve
To understand ON we need to revise some basic knowledge of the anatomy of the occipital nerves, Figure (1) :
– Greater Occipital Nerve (GON): arises from the C2 dorsal ramus and then passes medially to the lower border of the obliquus capitis inferior muscle then crosses the suboccipital triangle. It then runs along the rectus capitis posterior major muscle, innervates and pierces the semispinalis capitis muscle, pierces the tendon of the trapezius muscle passes the superior nuchal line of the occipital bone, and courses toward the apex of the scalp in the near of the occipital artery.
– Lesser Occipital Nerve (LON): arises from the C2 ventral ramus then loops inferior to the spinal accessory nerve then ascends along the posterior border of the sternocleidomastoid muscle penetrating the deep cervical fascia and runs across the posterior edge of the sternocleidomastoid muscle then splits into three branches: the auricular, mastoid, and occipital which called cutaneous branches of LON.
– Third Occipital Nerve (TON): arises from the dorsal ramus of C3 which divides into lateral and medial branches then, the medial branch gives rise to superficial and deep branches and the superficial branch is the third occipital nerve then curves around the dorsolateral surfaces of C2-C3 and travels along the semispinalis capitis muscle. It turns dorsally at the C2 spinous process and penetrates the semispinalis capitis, splenius capitis, and trapezius muscles and exits the muscles, and innervates a small cutaneous area right below the nuchal line. TON sends many branches to the greater occipital nerve and lesser occipital nerve which makes it difficult to distinguish the symptoms of isolated third occipital neuralgia.5
For GON, many areas may be compressed and result in neuralgia which include:
• C2 nerve root.
• Obliquus capitis inferior muscle.
• Semispinalis capitis muscle.
• Instances where the nerve penetrates the trapezius muscle.
• Instances where the occipital artery and greater occipital nerve intersect.
The occipital nerve is large, measuring 2.5 to 3.5 mm in diameter, which makes it more likely to be compressed.
Muscle hypertrophy, tensing, or spasm of muscles in the area contribute to compression. The condition is associated with stress and anxiety in many patients, and surgical sectioning of muscles in close approximation with the greater occipital nerve shows a relief of the pain of occipital neuralgia. In some instances, trauma and the formation of fibrocartilage calluses or other structural changes to the bony anatomy of the skull or spine can lead to this condition. Additionally, arteriovenous malformations may contribute to nerve compression.5
The pain is caused by irritation or injury to the occipital nerves which can be a result of 6 :
• Trauma to the back of the head.
• Pinching of the nerves by overly tight neck muscles.
• Compression of the occipital nerves as they leave the spine due to osteoarthritis, tumors such as schwannomas, or other types of lesions in the neck.
• Localized inflammation or infection, gout, diabetes, blood vessel inflammation (vasculitis).
• Frequent lengthy periods of keeping the head in a downward and forward position.
However, In many cases, no cause can be found and we confirm the diagnosis with a positive response (relief of the pain) after administration of an anesthetic drug causing nerve block.5
Causes of ON can be classified into vascular, neurogenic, muscular, and osteogenic causes as summarized in the table:
| Category | Causes of irritation |
| Vascular | •Irritation of the C1/C2 nerve roots by an aberrant branch of the posterior inferior cerebellar artery. • Dural arteriovenous fistula at the cervical level. • Bleeding from bulbocervical cavernomas. • Cervical intramedullary cavernous hemangioma. • Giant cell arteritis. • Fenestrated vertebra artery pressing on C1/C2 nerve roots. • Aberrant course of the vertebra artery. |
| Neurogenic | • Schwannoma in the area of the craniocervical junction: schwannoma of the occipital nerve. • C2 myelitis. • Multiple sclerosis. |
| Osteogenic | • C1/C2 arthrosis, atlantodental sclerosis. • Hypermobile C1 posterior arch. • Cervical osteochondroma. • Osteolytic lesion of the cranium. • Exuberant callus formation after C1/C2 fracture. |
Diagnosis:
Diagnostic Criteria of The International Classification of Headache Disorders 3 (ICHD3) 6:
- Unilateral or bilateral pain in the distribution(s) of the greater, lesser, and/or third occipital nerves and fulfilling criteria B-D
- Pain has at least two of the following three characteristics:
- recurring in paroxysmal attacks lasting from a few seconds to minutes
- severe in intensity
- shooting, stabbing, or sharp in quality
- Pain is associated with both of the following:
- dysaesthesia and/or allodynia apparent during innocuous stimulation of the scalp and/or hair
- either or both of the following:
- tenderness over the affected nerve branches
- trigger points at the emergence of the greater occipital nerve or in the distribution of C2
- Pain is eased temporarily by a local anesthetic block of the affected nerve(s)
- Not better accounted for by another ICHD-3 diagnosis.
Clinical Presentation
Patients with ON present with a shooting or stabbing pain in the neck that radiates over the cranium. The pain is characterized as persistent, paroxysmally aggravating, and lasts for seconds to minutes also vision impairment, ocular pain, tinnitus, dizziness, nausea, and nasal congestion can be present.5
Sensitivity to all forms of stimulation is common including sensitivity to light and touch, and dental pain may be present as the occipital nerve innervates the area around the ear, so patients with occipital neuralgia may feel pain in their back teeth. Developing one of these symptoms can indicate other conditions, but when they are developed together, they provide indicators for an occipital neuralgia diagnosis.6
Also, we can diagnose it in addition to patients’ history by physical examination shows:
○ The tenderness that is detected by palpation along the course of the GON (over the occipital protuberance) and/or the LON (about 3 cm superomedially to the tip of the mastoid process).
○ Tingling may be evoked by light pressure or percussion on the nerve (Tinel’s sign).
○ When patients lie on a pillow and hyperextend or rotate their neck, pain can occur (“pillow sign”).
On physical examination, tenderness along the course of the GON and LON can be observed and positive Tinel’s sign may be present over the nerve’s distribution, especially where the GON emerges at the base of the skull, hypoesthesia or dysesthesia can also occur.
The pain is located in the occipital area and may spread toward the vertex. The pain may be unilateral or bilateral but almost always begins unilaterally and may extend into a bilateral distribution over time. Bilateral symptoms are present in one-third of cases.7
work up:
- Imaging studies6
○ MRI is the most useful tool in the diagnosis of ON because it enables visualization of the surrounding cervical and occipital soft tissues to exclude their related diseases.
○ A simple X-ray is useful to exclude underlying pathologies, such as arthritis and craniocervical instability.
○ CT scan of the craniocervical junction can show neoplastic or degenerative bony diseases. - Diagnostic block
This is done by anesthetic drugs with or without steroid injections that reduce inflammation, and block the transmission of pain signals to the brain, thus inhibiting the sensation of headache pain, but it isn’t used only as a treatment tool but also used as a diagnostic tool. If a block in the occipital nerve relieves the pain, it can help confirm the diagnosis of ON, we need to know that occipital nerve block relief is not specific for ON and that false-positive results occur with migraine and cluster headaches.6
Risk Factors 7.8
People with these conditions have a higher risk for ON:
• Current or previous neck injuries either whiplash which is commonly caused by rear-end car accidents or other types of injury which can be caused due to falling or an injury while playing sports.
• Previous surgery to the head or neck.
• Congenital or acquired structural defects in the head or neck/ spine such as fractures, scoliosis, kyphosis, etc.
• Repetitive stress/strain on the neck as in looking downwards on a regular basis may lead to stiff neck muscles that begin to compress one or more occipital nerves.
• Tumors and infections: tumors along the neck and spine or infections may result in nerve compression or inflammation along the muscles of the neck and shoulders. These two causes of occipital neuralgia are rare.
• Inflamed blood vessels
• Diabetes: diabetic patients are at a higher risk of headaches and head pain related to damage to their vascular system because poorly controlled diabetes can result in highly variable blood sugar that damages veins. Although diabetic pain is usually confined to the lower extremities, it can occur in the form of occipital neuralgia as well.
• Arthritis.
• Gout: is not a common cause of occipital neuralgia, but it still can occur. It is a type of arthritis that occurs when uric acid collects in the joints which causes inflammation and pain.
Differential diagnoses:
Several disorders have some similar features to ON, such as pain in the back of the neck and head, so sometimes difficult to distinguish these disorders unless other features are present.
First, we should exclude tumors, infections, and congenital anomalies such as Arnold-Chiari malformation. It is important to exclude these conditions because if they are missed by clinicians, catastrophic results may occur.6
Second, ON may be mistaken for migraine, cluster headache, tension headache, or hemicrania continua. ON must be distinguished from the cervicogenic headache which is a referred pain from the cervical structures as bones or soft tissues in the neck such as atlantoaxial or upper zygapophyseal joints or from trigger points in neck muscle or their insertions, ON can be distinguished from it by knowing that ON is a neuralgia from the occipital nerve, whereas cervicogenic headache is nociceptive referred pain from cervical structures.6
Treatment:
There are many options for ON treatment, but the most conservative treatments, such as immobilization of the neck by the cervical collar, physiotherapy, and cryotherapy don’t show better performance than a placebo.
Drugs such as non-steroidal anti-inflammatory drugs, tricyclic antidepressants, serotonin-norepinephrine reuptake inhibitors, and anticonvulsants may help to relieve symptoms, and also doing therapeutic blocks after the diagnostic nerve blocks may be done.4
Botulinum Toxin injection has emerged as a treatment with lower side effects than many other techniques, with most recent trials showing 50% or more improvement.
It remains a common practice to use a landmark-only approach when performing greater and lesser occipital nerve blocks. For the blockade of both nerves, medication is infiltrated along the nuchal ridge although it’s easy to perform and relatively safe if done correctly, this technique may not be remarkably accurate and, as a result, could theoretically increase the risk of a false-positive result. To improve accuracy, ultrasound-guided techniques were developed. The original ultrasound-guided technique for injection of the GON targets the nerve as it courses superficial to the obliquus capitis inferior muscle at the C1-C2 level.
There are several advanced interventional procedures in clinical use including:
• Pulsed or thermal radiofrequency ablation (RFA) is used for longer-lasting relief after a diagnostic local anesthetic blockade is done. Thermal RFA aimed at destroying the nerve architecture can render long-term analgesia but also causes the potential risks of hypesthesia, dysesthesia, anesthesia Dolorosa, and painful neuroma formation. Chemical neurolysis with alcohol or phenol carries equal risks as thermal RFA, there is no such risk with pulsed RF; however, some questions compare its efficacy with other procedures.
• Neuromodulation of the occipital nerve(s) involves the placement of nerve stimulator leads in a horizontal or oblique orientation at the base of the skull where the greater occipital nerve emerges. Patients first should trial with temporary leads, and if it shows more than 50% pain relief for several days, so
is considered a successful trial, after which permanent implantation can be done. Neuromodulation also carries potential risks such as surgical site infection and lead or generator displacement or fracture after the operation.
• Ultrasound-guided percutaneous cryoablation of the GON is a commonly performed procedure. At the correct temperature, there should be stunning but not permanent damage to the nerve, but at temperatures below negative 70
degrees Celsius, nerve injury is possible.
• Surgical decompression is often considered to be the last option. A study of 11 patients shows that only two patients don’t experience significant pain relief postoperatively. By surgical decompression, the mean pain episodes per month decreased from 17.1 to 4.1, also mean pain intensity scores decreased from 7.18 to 1.73. Resection of part of the obliquus capitis inferior muscle shows success in patients who experience exacerbating pain with flexion of the
cervical spine.4
Another popular surgical procedure is C2 gangliotomy, even though patients get several days of intermittent nausea and dizziness. As with any large nerve resection, there is a risk of developing a deafferentation syndrome, but the risk
is lower if the resection is pre-ganglionic.4
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