First bite syndrome – Clinical presentation, Diagnosis and Treatment

First bite syndrome is a clinical condition occurring as a complication of surgeries involving the infratemporal fossa, deep lobe of the parotid gland, parapharyngeal spaces and manipulation or ligature of the external carotid artery. Sometimes it can also be caused by a head and neck tumor itself arising in above locations.

The condition is characterized by unilateral cramping or spasm in the region of the parotid gland resulting in severe pain when the patient takes the first bite of every meal in the postoperative period. The pain often radiates to the ipsilateral ear and diminishes over the next several bites.

The clinical condition was first described by Haubrich in 1986 and the term “first bite syndrome” was used in 1998 by Netterville et al.

Why first bite syndrome happens?

The exact etiology of first bite syndrome is still unknown. Most accepted reasoning is injury to the cervical sympathetic chain during surgery.

Myoepithelial cells of parotid gland receive dual sympathetic and parasympathetic innervation, which act synergistically and not antagonistically.

It is believed that these surgeries may result in sympathetic denervation to the parotid gland, specifically to its myoepithelial cells. Uninhibited release of parasympathetic neurotransmitters (acetylcholine) during salivation and mastication would results in “supramaximal” contraction of the myoepithelial cells causing pain. 

Desensitization occurs after successive bites and the symptoms improve with mastication, which then reoccur with the first bite of the next meal.

However, this hypothesis has not been proven, because not all patients who have undergone sectioning of the cervical sympathetic chain during surgery have this complication.

There are various other clinical syndromes also which are associated with cervical sympathetic trunk injury. They are tabulated below.

Signs and Symptoms

Most often, first bite syndrome is a minor complication, which often goes unnoticed. Hence the exact prevalence of the disease after head and neck surgeries is unknown. Literature reports an incidence of 7-10% after surgeries of infratemporal fossa, deep lobe of the parotid gland and parapharyngeal space.

In some patients, the symptoms can be very intense making eating difficult which can even affect quality of life.

Patients may even avoid eating due to the severity of this syndrome. Some patients may have pain even while thinking of food, due to the salivation that occurs.

Differential diagnosis

Following are some clinical conditions which may mimic first byte syndrome in clinical presentation.

• Temporo-Mandibular Joint Dysfunction / TMJ Syndrome
• Glossopharyngeal neuralgia
• Eagle’s syndrome or styalgia

Investigations

First bite syndrome is a clinical diagnosis and needs no special investigations for diagnosis, when it occurs during the days following neck surgery.

Imaging is needed when a patient presents with similar condition, in the absence of a history of ipsilateral upper neck surgery. This is to exclude a tumor of the deep lobe of the parotid gland, submandibular gland or ipsilateral parapharyngeal space, as the tumor may only become visible several months after onset of the pain.

What’s the treatment for first bite syndrome

In most patients the symptoms are tolerable and tends to diminish over time or may resolve spontaneously. There exists no definitive treatment for this condition. But following treatment options are considered in those patients who are very symptomatic.

1. Change in behavior: Manual compression of the painful region by the patient sometimes helps to relieve the pain, leading the patient to press on the painful region preventively before taking the first bite.
2. Avoidance of sialagogue foods (acid): The pain is usually intense with sialagogue foods. But this was not shown to be so effective.
3. Non-steroidal anti-inflammatory drugs (NSAIDS) and usual analgesic treatments have poor results.
4. Drugs used for treatment of chronic neuralgia and neuropathic pain such as pregabalin, gabapentin and carbamazepine are used alone or in combination with tricyclic antidepressants (amitriptyline) by some, though they are not demonstrated to be completely effective.
5. Anesthetic sprays or local anesthetic block and tympanic neurectomy or auriculotemporal neurectomy have not been demonstrated to be effective.
6. Local radiotherapy can lead to resolution of postoperative first bite syndrome, but is a radical procedure associated with risks and/or functional sequelae which itself can worsen quality of patient’s life.
7. Total partoidectomy is found to be effective, confirming the role of the parotid gland in the pathogenesis of this syndrome.
8. Intra-parotid injection of botulinum toxin type A is found to be effective both in terms of analgesia and improvement of quality of life and is currently appears to be the most effective first-line treatment option for first byte syndrome. Botulinum toxin inhibits the release of acetylcholine from nerve synapses resulting in reduced contraction of the glandular cells and their secretion.
   However, a standard method has not yet been defined and the protocol varies from three successive injections of 11 units to a single injection of 75 units. Patient may need repeated injections once the effect of botulinum toxin weans off.

Does first bite syndrome go away?

Sometimes, first bite syndrome goes away on its own. But in some cases, symptoms can last a long time which may affect patient’s quality of life.

References

1. Laccourreye O, Werner A, Garcia D, Malinvaud D, Huy PT, Bonfils P. First bite syndrome. European Annals of Otorhinolaryngology, Head and Neck Diseases. 2013 Nov 1;130(5):269-73.
2. Linkov G, Morris LG, Shah JP, Kraus DH. First-Bite Syndrome: Incidence, Risk Factors, Treatment, and Outcomes. Journal of Neurological Surgery Part B: Skull Base. 2012 Feb;73(S 01):A126.
3. Deganello A, Meccariello G, Busoni M, Franchi A, Gallo O. First bite syndrome as presenting symptom of parapharyngeal adenoid cystic carcinoma. J Laryngol Otol. 2011;125:428-431.
4. Chiu AG, Cohen JI, Burningham AR, Andersen PE, Davidson BJ. First bite syndrome: a complication of surgery involving the parapharyngeal space. Head & Neck: Journal for the Sciences and Specialties of the Head and Neck. 2002 Nov;24(11):996-9.
5. Costales-Marcos M, Álvarez FL, Fernández-Vañes L, Gómez J, Llorente JL. Treatment of the first bite syndrome. Acta Otorrinolaringologica (English Edition). 2017 Sep 1;68(5):284-8.
6. Abdeldaoui A, Oker N, Duet M, Cunin G, Huy PT. First Bite Syndrome: A little known complication of upper cervical surgery. European annals of otorhinolaryngology, head and neck diseases. 2013 Jun 1;130(3):123-9.