Hyoid Bone Syndrome
The hyoid bone has been identified with a specific, although not well recognized, pain syndrome for over 40 years.2 The painful symptoms are generally caused by trauma at the greater cornu of the hyoid bone with the pain radiating to other sites.3
Treatment for the condition ranges from injections of local anesthetic or cortisone to resection of the greater cornu. The pain usually radiates from the greater cornu of the hyoid bone to the throat, mandible, mandibular molar teeth, zygomatic arch, condyle, face, ear, and temple superiorly; anteriorly to the neck, clavicle, upper half of the breast, shoulder, arm, and over the shoulder to the scapula of the back inferiorly on the same side.4
The condition is not well known in medicine and dentistry for at least two reasons: (1) the diffuse and seemingly unrelated radiation of symptoms and (2) the apparent absence of histopathologic evidence of injury.
Hyoid bone syndrome was first described by Brown2 in 1954, and later by Steinmann,5 Kopstein,6 Lim,3 and Ernest.4 The syndrome represents a group of confounding head and neck symptoms that may suggest carotodynia7 to the unsuspecting clinician. The primary site of pain is associated with the region of the greater cornu tip of the hyoid bone. Steinmann,5 Kopstein,6 Lim,7 and Ernest have reported surgical removal of the greater cornu with remarkable resolution of pain for the affected patient. However, some clinicians deny the existence or the validity of hyoid bone syndrome because reports offer no objective evidence other than the signs, symptoms, and results of surgery.
This article presents photomicroscopic evidence to validate the hyoid bone syndrome, and reports a focal, degenerative injury of the middle pharyngeal constrictor muscle (MPCM) as the site of a painful injury associated with hyoid bone syndrome. The site of injury involving the MPCM is consistent on a clinical, anatomic, and histopathologic basis with a description of the somatic tissue responsible for the painful constellation of symptoms of hyoid bone syndrome.
The hyoid bone is the only bone that has no direct contact with any other bone in the human body (see Figure 1). It is a U-shaped structure lying between the root of the tongue and mandible and the thyroid cartilage. The hyoid bone forms a movable base for the tongue and its varied movements and is held in position by a large number of muscles. The hyoid bone has connections with muscles to the mandible (mylohyoid), tongue (hyoglossus), skull (stylohyoid), thyroid cartilage (thyrohyoid), sternum (sternohyoid), to the medial border of the scapular notch (omohyoid), and to the pharyngeal median raphe (MPCM) (see Figure 2).
Most patients with symptoms of hyoid bone syndrome report pain radiating to the ear, throat, temple, zygomatic arch, temporomandibular joint (TMJ), mandibular molar teeth on the same side, and a vertical axis of pain that runs from the temple superiorly down through the TMJ, continuing inferiorly to the clavicle, and terminating in the middle of the breast without extending below the nipple (see Figure 3).4 The connections to the hyoid bone explain the radiating symptoms experienced by the patient suffering from hyoid bone syndrome.
Methods and Material
A 43-year-old woman was referred for evaluation of chronic pain, of 13 years’ duration, of the left side of the head, face, neck, and shoulder. Although trauma is usually the source of such a complaint, the patient could not recall a specific event correlating with the onset of her symptoms. She had undergone multiple surgical procedures in the hope of achieving remission of the pain. The right and left TMJs were operated by open reduction without successful relief of pain. Subsequently, two separate surgical procedures were performed on the left maxillary sinus, again without benefit to the patient.
Diagnostic testing included digital or bimanual palpation with the index finger on the greater cornu of the non-affected side. This procedure directed the entire hyoid toward the surface of the skin of the affected side, with the thumb stabilizing the affected cornu at the site of injury, as recommended by Brown.2 When pressure was applied to the left cornu, the radiation of painful symptoms was intensified when pressure was maintained. Next, a local anesthetic syringe with a 30-gauge, 1-inch needle containing bupivacaine (0.5%) with epinephrine 1:200,000 (Marcaine) was inserted on the superior surface of the left greater cornu at the site of pain (see Figure 4). One cubic centimeter of Marcaine deposited at the site of injury resolved more than 95% of the pain present at all reference sites and at the point of origin within a few minutes. The sites included the ear, temple, TMJ, zygomatic arch, mandible and mandibular molar teeth, throat, anteriorly to the neck, clavicle, shoulder, arm, and upper half of the breast.
This test was repeated the following day with identical successful results. An anesthetic block for treatment of hyoid bone syndrome eliminates almost all of the pain, yet the patient still has a persistent soreness that is not affected by the block. However, the soreness is eliminated by surgical operation.
Each time after the effect of the anesthetic wore off, the patient’s original pain pattern reappeared. Consultation was sought with a radiology service, and neck radiographs with lateral, oblique, and Allen position views were obtained. No evidence of fracture of the hyoid body or cornua, or other unusual findings were revealed.
The other structures tested that could mimic hyoid bone syndrome included the anterior scalene muscle (Scalenus Anticus Syndrome), the stylomandibular ligament (Ernest Syndrome), the temporal tendons (Temporal Tendinitis), the carotid artery (carotodynia), the pharynx (tumors and infections), and the trigeminal and glossopharyngeal cranial nerves (neuralgias). With the differential diagnosis reduced to the left greater cornu of the hyoid bone, the patient was scheduled for surgery.
With the patient under general anesthesia with oro-tracheal intubation, the head and neck were positioned in lateral hyperextension, with the face positioned to the right. A skin marker was used to identify the relative position of the body and left greater cornu of the hyoid bone. Local anesthetic was infiltrated into the skin and underlying tissues to reduce hemorrhage at the site of surgery. The skin incision was carried subcutaneously to identify the platysma muscle. Next, palpation and blunt dissection of the greater cornu was aided by displacement of the hyoid bone as reported by Brown,2 thus providing easier location and dissection of the greater cornu.