Abstract
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Vertebral osteomyelitis is a relatively rare condition and comprises 2% to 7% of all hematogenous bone infections; furthermore, only 6.5% are located in the cervical region. 1 The mortality rate ranged from 25% to 71% before the antibiotic era. 2 The use of antibiotics has decreased the rate, but the incidence of pyogenic vertebral osteomyelitis in recent years appears to have increased. 1 Because of its insidious and sometimes bizarre clinical presentation, there is usually a considerable delay in diagnosing pyogenic osteomyelitis. This delay is even longer when vertebral osteomyelitis is complicated by neurologic involvement. Few cases with this bizarre presentation associated with retropharyngeal abscess have been reported.
In this article we describe a case initially diagnosed as a retropharyngeal abscess that proved to be cervical vertebral osteomyelitis.
CASE REPORT
On July 14, 1994, a 72-year-old man suddenly had chills and a pain in the posterior neck that radiated to both shoulders during the night. As the pain persisted through the next morning, he sought medical assistance at a nearby general hospital. A lateral radiograph revealed an expanded retropharyngeal space. The attending otolaryngologist diagnosed this condition as retropharyngeal abscess and immediately initiated antibiotic (cefpodoxime proxetil [Banan]) therapy.
On July 19, the sixth day of his illness, he was transferred to the University of Tokyo Hospital because of the persistent pain. On admission, he had severe tenderness of the left posterior neck that radiated to both shoulders. A fiberscopic examination disclosed that the posterior wall of the hypopharynx was hyperemic and swollen. Although the hypopharynx was swollen, the airway was not obstructed. The peripheral white cell count was 12,400/mm3, and the C-reactive protein level was elevated to 22.5 mg/dl. The elevated serum glucose value of 262 mg/dl and high HbA1C rate of 8.8% indicated that the patient's diabetes was out of control. CT scans revealed the presence of a developing partially phlegmonous abscess posterior to the posterior wall of the pharynx at the C5 level (Fig 1). Because the abscess was located lower than the mesopharynx, the patient did not report dyspnea. The patient's response to a tuberculin test was negative.
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Postcontrasted axial CT scan at C5 level. Area of low density was revealed on the forward portion of the vertebral body (arrows).
High-dose antibiotic therapy was initiated. Every 6 hours the patient was given both 1.6 gm of intravenous potassium clavulanate ticarcillin sodium (Augpenin) and 600 mg of clindamycin (Dalacin). On the second day after the admission, numbness of the limbs appeared and progressed. Bladder dysfunction was also noted. The patient had a previous diagnosis of prostatic hypertrophy so that the bladder dysfunction was not thought to be related to the deep neck abscess.
On the fourth day, the sensory disturbance progressed, and the patient's lower limbs became severely weakened. Neurologists diagnosed that the phlegmonous condition had spread to the surrounding tissue and that the edematous intracanal tissue pressed against the spinal cord. Antibiotic therapy was continued as the phlegmonous state began to resolve and the inflammation seemed to be decreased. The request for an MRI was rejected by a radiologist.
On the fifth day, weakness of the upper limbs was noted. CT scans revealed that the phlegmon had developed into an abscess (Fig 2A) and another abscess had developed at the anterior portion of the left side of the vertebral body at the C6 level (Fig 2B). Because the neurologic sign progressed, a surgical incision and drainage was performed. The approach was externally through an incision along the superior aspect of the left sternocleidomastoid muscle because the abscesses were located deep and far from the oral cavity. Two smooth masses were found; one was posterior to the pharynx at the level of the thyroid cartilage, and the other was behind the longus colli muscle at the level of the cricoid cartilage. The abscess contained yellowish pus and granulation tissue. The abscesses had no direct connection with each other.
After the operation, the lower limbs slowly recovered in strength. However, the cervical pain and the lower-limb numbness persisted. On the seventh day, an MRI revealed osteomyelitis at the C5 to C6 level, diskitis at the C5 to C6 level, and an epidural abscess at the same site (Fig 3). The patient underwent urgent surgery; the same approach as the surgical incision to drain the retropharyngeal abscesses was accepted, the infected and severely friable C5 and C6 vertebral bodies were removed by burr, and the epidural abscess was drained. The cervical bodies were reconstructed by an iliac bone graft. Methicillin-susceptible Staphylococcus aureus was cultured from the intraoperative specimen. The patient was treated intravenously with 1.6 gm of potassium clavulanate ticarcillin sodium every 12 hours after the operation.
The patient improved slowly after the operation. On September 19, 56 days after surgery, he was discharged from the hospital, having completely recovered from muscle weakness of the upper and lower limbs and sensory disturbances of the lower limbs.
DISCUSSION
The severe friability of the vertebral bodies suggest that the infection might have originated in the vertebral body. The presence of two separate retropharyngeal abscesses also suggested they were caused by the infection of the vertebral bodies. Because the neurologic signs appeared a week after the retropharyngeal abscess was noted, the epidural abscess might have formed later than the retropharyngeal abscesses. The primary focus of the infection was not detected.
The pathophysiology of pyogenic vertebral osteomyelitis depends to a major degree on anatomic considerations. The small amount of fatty tissue and the poor venous plexus of the epidural space of the cervical area cause fewer infections to the cervical vertebral bodies than thoracic or lumbar bodies. 3 Moreover, few cases of osteomyelitis complicating retropharyngeal abscess have been reported. 4 – 7 Thus it must be very difficult even for a neurologist to distinguish a cervical vertebral osteomyelitis from a case of deep neck infection showing muscle weakness and sensory disturbance. The most important point in the diagnosis and treatment of vertebral osteomyelitis is the knowledge and consideration of this disease. Imaging studies play an important role in the evaluation; however, lateral radiographs or CT scans of the cervical area did not reveal any indications of the vertebral osteomyelitis or the epidural abscess in this case. Inappropriate bony windows of CT scans failed to rule out vertebral osteomyelitis in our case. MRI was proven most useful for accurate detection of a vertebral osteomyelitis and an epidural abscess at any rate. Because the thick ligament longitudinale anterius covers the anterior aspect of the vertebral bodies, infection of the vertebral bodies is unlikely to spread to the retropharyngeal space.
Table 1 shows a decreasing mortality rate and an increasing morbidity rate; only 2 of 20 patients (10%) died, whereas 11 (55%) did not recover completely. The development of antibiotic therapy has decreased the mortality rate 1 ; however, antibiotics should be used in addition to curettage of friable vertebral bodies and surgical decompression. Faidas et al. 7 continued antibiotic therapy after MRI revealed a vertebral osteomyelitis. This patient had mild residual weakness and used a cane for ambulatory support because of delayed surgical decompression. Eismont et al. 8 reported that diabetes mellitus, rheumatoid arthritis, advanced age, the presence of S. aureus, and a more cephalad location of the vertebral infection are all risk factors of the occurrence of secondary paralysis.
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CT scan on the fifth day.
Otolaryngologists may be confronted with patients having osteomyelitis of the cervical vertebra. All patients are at risk for the occurrence of paralysis. Table 1 demonstrated that 14 of 20 cases (70%) were infected with S. aureus. Because ampicillin consistently ranks as one of the most powerful agents available for methicillin-susceptible S. aureus, ampicillin must be administered intravenously for initial empiric antibiotic treatment. If conservative therapy fails to improve the patient's condition, an infection of antibiotic-resistant S. aureus should be considered, and immediate surgical decompression of an abscess and additional curettage should be strongly considered.
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Gadolinium-enhanced, T1-weighted sagittal MRI on the seventh day. High-intensity signal was revealed on the C5 and C6 vertebral bodies (asterisks) and the C5 to C6 disk, and a signal of low intensity was revealed in the epidural space at the C5 and C6 levels (arrows).
Kulowski and Missouri 2 reported that injury of the total spinal cord by the epidural abscess was caused by direct compression, inflammatory edema, and septic thrombosis of the spinal veins, which caused central nervous system complications. Direct compression was thought to be the most important factor. Table 1 demonstrated that 12 of 13 cases (92%) of cervical vertebral osteomyelitis had epidural abscess with muscle weakness and sensory disturbance. The abscess must have been caused by the infection of the vertebral bodies, which caused muscle weakness and sensory disturbance.
Heusner 9 reported that the symptoms that invariably unfold from the epidural abscess are in the following four distinct phases with regard to the manifestations of an epidural abscess: phase 1, spinal ache; phase 2, root pain; phase 3, weakness of the voluntary muscles, sphincter, and/or sensibilities; and phase 4, paralysis.
Pyogenic cervical vertebral osteomyelitis with muscle weakness and sensory disturbance
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C., Coccidioides, M., microaerophilic, H., Haemophilus.
Completion of surgical decompression before paralysis sets in leads to a good prognosis. After 48 hours of paralysis, surgery may save the patient's life, but the neurologic damage is probably irreparable. 9 Thus cases of deep neck infection with central nervous system complication must be considered to be vertebral osteomyelitis and quickly decompressed. In our case, on the second day after admission, bladder dysfunction appeared and the patient reached phase 3. Because his symptoms fortunately never reached phase 4, he recovered completely, although 7 days had passed without any effective treatment.