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7 Articles in Volume 4, Issue #6
Atypical Earache Otomandibular Symptoms
Atypical Facial Neuralgias
Chronic Pain, Osteoporosis, and Bone Density Testing
Pelvic Floor Tension Myalgia (PFTM)
Promising Therapies Using Botulinum Toxin
The IP Network: A Case for Intractable Pain Centers Part II
Trigger Point Low Level Laser Therapy

Atypical Facial Neuralgias

Persistent burning or lancinating facial pain with no clear etiology may point to a diagnosis of neuropathic pain.

Neuralgias are syndromes characterized by intermittent attacks of sharp and paroxysmal pain along the course of a nerve. The neuralgias involving the face are often misdiagnosed and seen initially by the dentist or otolaryngologist. Therefore treatment is often delayed and patients may unnecessarily suffer from neuropathic pain until someone correctly recognizes the signs and refers the patient to a neurologist. The authors describe some of the atypical and lesser-known neuralgias of the face.

Occipital Neuralgia

Neuropathic pain originating in the back of the head along the distribution of the occipital nerves is called occipital neuralgia (see Figure 1). The greater occipital nerve, which originates from the posterior root of the second cervical nerve in the neck, is the most common nerve to be involved. The lesser occipital nerve, arising from the posterior branch of the third spinal nerve in the cervical spine and situated behind the mastoid, is less commonly affected.

Etiology

Occipital neuralgia is most commonly idiopathic in that no causative factor can be identified. It can sometimes be secondary to injury to the nerve (e.g. direct trauma to the occipital nerves from a whiplash hyperextension injuries), compression of the nerve (between atlas and axis), or the upper cervical roots from arthritic changes in the spine (rheumatoid arthritis and ankylosing spondylitis).1 Compression of the occipital nerve has been described along its course up the neck-while exiting from the semispinalis capitis or trapezius muscles-from everyday activities such as leaning against the back of a chair for an extended period of time. There are also rare occurrences where structural pathology like tumors involving the 2nd and 3rd cervical dorsal roots and sometimes developmental abnormalities can also be causative.

Symptoms and Signs

The pain associated with greater occipital neuralgia is intermittent, sharp, jabbing or throbbing and usually starts in the suboccipital region at the base of the skull near the midline, involves the entire posterior and lateral scalp, and usually radiates towards the vertex. Insult or injury to the lesser occipital nerve will cause pain around the mastoid process and radiate to areas near the ear and lower temple. Pressure on the suboccipital region over the occipital nerve will reproduce pain with radiation. Severe cases may actually have Tinel’s sign in which tapping on the area of the nerve causes sharp, throbbing pain and tingling. One may encounter extreme tenderness upon palpation over the occipital notches and upper cervical region with paroxysms of pain. On sensory exam, there may be hypesthesia or dysesthesia or paresthesia in the posterior scalp. Patients may also report spasms of the para vertebral muscles and restriction of neck movements.

Diagnosis

Diagnosis is mainly clinical and based on the localization of pain aligned with the distribution of the occipital nerves. An abnormal neuroexam should prompt imaging of the brain with MRI of cervical spine. The usual MRI sequences are not able to visualize the structural anatomy of the occipital nerves unless there is a gross abnormality like a large tumor.

Differential Diagnosis

Occipital neuralgia can present like migraine, with unilateral, throbbing pain especially when it radiates to the frontal, orbital and periorbital region.2 Sometimes nausea, vomiting, photophobia or phonophobia, and eye changes may accompany occipital neuralgia and mimic a migraine. The situation is further complicated by the ability of occipital nerve blocks to relieve migraine headaches and the fact that both these disorders seem to coexist. One study showed that out of 500 patients suffering from migraine headache, almost 40% treated by occipital nerve block had relief of their migraine.

One way to distinguish the two is that typical acute treatment for migraine like the Triptans or ergot alkaloids will not work for occipital neuralgia. The explanation for this seemingly common overlap in presentation is based on neuroanatomical pathways. The C2, C3 nerves project to the nucleus caudalis of the trigeminal nerve, which as we now know, is a key player in generation of migraine headaches. Greater occipital neuralgia probably triggers the pain pathways arising from the nucleus caudalis and therefore can conceivably trigger a migraine attack. In a headache patient, examination should therefore include a thorough examination of the back of the head, and base of neck for tenderness along occipital nerves, apophyseal joints and mobility of the cervical spine.

Figure 1. Distribution of the occipital nerves. Figure 2. The glossopharyngeal nerve exits the skull through the jugular foramen behind the styloid process. Figure 3. Inflammation of the shenopalatine ganglion may affect sensory, motor, and autonomic functioning of the nose, mouth, and throat.

Treatment

The initial treatment is symptomatic with analgesics, muscle relaxants, soft cervical collar and physical therapy with gentle range of motion exercises especially head flexion. Local nerve blocking injections with steroids and local anesthetics can be very helpful for symptomatic relief of pain.3 It is hypothesized that depomedrol, a commonly used depot steroid agent for local nerve blocks causes demyelination of the nerve fibers and therefore provides relief of symptoms.

Surgical ablation procedures include sectioning either the peripheral nerve in the scalp or at the 2nd and 3rd cervical roots for medically intractable cases. Occipital nerve release has been attempted in one case series under the presumption that the nerve is commonly trapped while exiting either the trapezius or semispinalis muscle.4 Complete pain relief was not attained in any patient. The benefit from the surgery appeared short-lived and complications included denervation pain and neuroma formation along with recurrence or worsening of pain. Peripheral nerve electrostimulation is a relatively new modality of treatment where subcutaneous electrodes are placed on the occipital nerve which are then stimulated by a small distal generator placed superficially in the abdomen.5

Glossopharyngeal Neuralgia

This is a rare type of neuropathic pain originating from the 9th (glossopharyngeal) and sometimes also the 10th (Vagus) cranial nerves. It is therefore also called vagoglossopharyngeal neuralgia.6 The glossopharyngeal nerve exits from the skull through the jugular foramen, behind the styloid process, to supply the tongue and pharynx (see Figure2). It is responsible for sensory and motor supply to the pharynx, taste and general sensations from the back of the tongue, external ear and internal surface of the tympanic membrane, and salivation (supply to parotid gland). It also receives fibers from the carotid body and sinus and participates in the maintenance of blood pressure and sympathetic tone of blood vessels.

Etiology

It is usually idiopathic in nature. Secondary causes include nerve compression while exiting the neck by trauma, local infection or an elongated styloid process or tumors.7 Recent improvement in imaging techniques has resulted in better diagnosis of secondary causes of the neuralgia due to compression of the nerve root at its entry zone by an artery (vertebral or posterior inferior cerebellar artery) or vein and distortion by tumors like papillomas.

Symptoms and Signs

Typically patients have paroxysmal, lancinating pain on jaw movements, which radiate to areas innervated by the 9th nerve including external auditory canal and posterior oropharynx. These attacks of pain may be associated with syncope8, cardiac arrest, or even seizures, because of the close proximity of the glossopharyngeal nerve to the carotid body. Loss of taste at the base of tongue is sometimes reported. Neurological examination is usually entirely negative, but sometimes may show decreased oropharyngeal sensations, gag and cough reflex.

Diagnosis

Diagnosis is based on the clinical picture. Diagnosis and treatment of such patients is often delayed because they present first to otolaryngologist with vague symptoms of earache or a foreign body sensation inside the throat or tonsils. Referral to a neurologist is usually only initiated after multiple visits and a thorough workup, including direct and indirect visualization with laryngoscopy, to essentially exclude an ear, nose or throat problem. However, especially for intractable patients and patients willing to consider a surgical treatment option, MR Angiograms should be obtained to look for compression of the nerve by a blood vessel. MRI of brain with contrast can be non-diagnostic unless special thin cuts and sequences are obtained from the region of interest.

Treatment

Pharmacology is the first line in treatment and should include antiepileptics to control the neuropathic pain. Carbamazepine can be initiated at 200mg three times a day. Other antiepileptics can be added if maximizing the dose of carbamazepine is not effective and may include oxcarbemazepine, gabapentin or topiramate.

Surgical treatment is recommended for secondary pathology like tumor or for intractable neuropathic pain not responsive to medical treatment. Craniotomy of posterior fossa with transaction of 9th cranial nerve roots, which may later include the upper vagal nerve roots, may be initially attempted. Surgical techniques include either an intracranial section of the 9th and 10th cranial nerves or extra cranial section of 9th nerve. Recently there is increasing evidence that the nerve root may be compressed by a blood vessel and, if radiologic confirmation is present, then separating the nerve from the artery by teflon (a technique called microvascular decompression) is the treatment of choice. Sometimes mobilization of the vessel in contact with the nerves by gentle and direct manipulation of the nerve, without interspersing it with teflon, may result in relief of symptoms.

Complete, long-term pain-free relief has been reported in 60% patients in one large series.9 Complications of surgery included cranial nerve palsy and cerebrospinal fluid leak. Transient elevation of blood pressure after sectioning of the nerve has also been reported. There is some controversy regarding the micro vascular decompression. Over 50% of normal asymptomatic individuals may have an artery or vein in close proximity to the nerve roots. In patients with glossopharyngeal neuralgia, preoperative angiograms may not show the tortuous vessel or the compression.

Some experimental treatment modalities for intractable facial pain include direct electrical stimulation of the contralateral motor cortex by epidural electrodes.10,11

Sphenopalatine Neuralgia

Sluder first described this neuralgia in 1905 and observed that some patients recovering from inflammation of ethmoid and sphenoid sinuses were left with residual neuralgic pain. He attributed it to the spread of inflammation to the spheno-palatine ganglion and described a syndrome that included neuralgic, motor, sensory and gustatory symptoms. Sluder named it a “lower-half headache.”12

The sphenopalatine ganglion is a small traingular structure situated between the sphenoid and maxillary bones, behind the middle turbinate of the nase, 1-9 mm from the lateral nasal wall but separated from the nasal cavity by mucus membrane. It is the relay station through which many nerves pass and therefore problems with this region will cause dysfunction of nerves passing through it. The nerves passing through this ganglion include the maxillary nerve (sensory supply to nose, palate, tonsils and gums), greater petrosal and deep petrosal nerves (taste sensation, lacrimation and salivation) and medial pterygoid nerve which innervates the muscles of the soft palate. Irritation of the ganglion may therefore cause problems in the sensory, motor and autonomic functioning of the nose, mouth, and throat.

Etiology

This neuralgia can be idiopathic or secondary to irritation of the sphenopalatine ganglion due to infection of the sphenoid or posterior ethmoid sinuses, intranasal deformities, or scarring from previous sinus surgery. Some correctable intranasal deformity is often found with this neuralgia and therefore a thorough examination of the nasal and paranasal sinuses using imaging is essential.

Signs and Symptoms

Unilateral burning or aching pain initially starts at the base of nose, and then involves the cheek, eye, teeth, frontotemporal and mastoid region. Bilateral pain can occur on rare occasions. A metallic taste before or during attack and decreased taste sensation have been reported. Parasympathetic hyperfunctioning during an attack of pain include lacrimation, conjunctival injection, nasal obstruction, rhiniorrhoea and serous nasal discharge.

On neurological exam, there may be either loss of sensation or hyperesthesia of soft palate, pharynx, tonsils or nose. Sometimes elevation of the palatine arch on affected side and deviation of the uvula to the non-affected side can be seen.

Diagnosis

Diagnosis can be confirmed if symptoms are relieved by a sphenopalatine block, which can be achieved either by intranasal application of 5% cocaine solution, or a selective injection of 1% lidocaine through the greater palatine foramen. CT Scan or MRI of the paranasal sinuses to rule out underlying secondary pathology should be done.

Differential Diagnosis

Cluster Headaches can have a very similar presentation to this neuralgia. However the characterisitic periodicity and predominant severe stabbing eye pain is lacking in sphenopalatine neuralgia.

Treatment

Treatment of the underlying etiology is the first and foremost therapy for these patients. Infection of paranasal sinuses is usually treated with antibiotics or irrigation and drainage. Correction of anatomical defects, if any, should be done.

Destruction of the ganglion by surgical ganglionectomy13 or irradiation of the ganglion though the lateral wall of the nasal cavity by contact helium-neon laser has been described. Destruction can also be achieved by injection of 0.5 ml of 5% Phenol in 95% alcohol into the pterygopalatine fossa, if symptoms persist. Iontophoresis of the ganglion, which is a form of electro osmosis that introduces an electrical current into the tissue, is also a mode of therapy.

Combined Hyperactive Dysfunction Syndrome

Multiple cranial neuralgias involving the 5th, 7th, and 9th cranial nerves can occur together in the same patient. Thus a patient may present with trigeminal neuralgia (irritation of 5th cranial nerve), hemifacial spasm (irritation of 7th cranial nerve), and glossopharyngeal neuralgia at the same time. This condition is described as combined hyperactive dysfunction syndrome.14 This syndrome is most often secondary to irritation of the nerve roots due to compression by blood vessels which are usually situated too close to these nerve roots. Surgical treatment with separation of the artery from the nerve called microvascular decompression is the treatment of choice.

Conclusion

When patients present with persistent burning or lancinating paroxysmal pain in the facial region and no clear etiology, one should consider neuropathic pain in the diagnosis. There are many modalities of therapy currently available for such patients. Early recognition and treatment will also avoid the long-term psychological and physiological consequences of chronic pain. All neuropathic pain patients should be screened for presence of anxiety or depression commonly seen in such patients. It is important to treat these common comorbidities for successful management of the neuropathic pain. n

Last updated on: January 5, 2012
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