CASE REPORT
Case 1
A 38-year-old woman was diagnosed with thalassaemia major for the past 26 years. She underwent splenectomy 12 years ago and was recently diagnosed to have Hepatitis C. She presented with a two weeks history of progressive painful right neck swelling which was associated with dysphagia, odynophagia and fever. She was referred to our hospital for unresolved neck swelling after a course of oral anti-biotics. On admission, the patient appeared ill, dehydrated, with pallor, jaundice and fever. Examination showed the patient to be hypotensive, associate with tachycardia. There was a diffuse swelling at the right lateral side of the neck measuring about 10x12 cm. The swelling was soft in consis-tency, inflamed and tender. She had trimus, and her oral hygiene was poor. Oropharyngeal examination showed me-dialization of the right lateral pharyngeal wall. Further examination by flexible naso-pharyngolaryngoscopy noted inflamed and edematous hypopharynx. Her full blood count showed a Hb of 5.7g/dL, TWBC of 47.8 x 103/L and platelet count of 267 x 103/L. Her total bilirubin was elevated (188umol/L). Her renal profiles and chest x-ray (CXR) were within the normal range. She was transfused with four pints packed cells and her Hb rose to 9.8g/dL. Broad-spectrum intravenous (IV) antibiotic was started empirically and septic shock was treated accordingly. An urgent computed tomography (CT scan) was performed and revealed a large collection of pus extending from the inferior part of the right parotid gland to the base of the neck (Figure 1a) and medially to the right carotid space at the level oropharynx. The right sternoclei-domastoid muscle was displaced postero-laterally. Multiple subsmall lymph nodes from level I to III were present the largest measuring about 6mm at the level of the submental lymph node. There was also thrombosis of right internal jugular vein (Figure 1b). The patient was further sta-bilized by the hematology team. Right neck exploration and drainage of the abs-cess was carried out under general anes-thesia after the patient’s general condition was stabilized. Intra-operative findings re-vealed multiple loculated areas in the right parapharyngeal space, filled with 50cc thick pus with minimal slough. She deve-loped acute pulmonary edema post-operatively and was nursed in the High Dependency Unit (HDU), under close monitoring by the hematology and anesthe-siology team. The pulmonary edema re-solved by day four post operatively. She was then discharged from HDU to the normal ward. The pus and blood culture and sensitivity revealed Klebsiella spp. and both were sensitive to ceftriaxone sodium (Rocephin). She was then put on IV Rocephin 1gm daily with dressing twice daily over the cervical wound. On the tenth post operative day, the patient was discharged and advised to come for daily dressing to the clinic nearest her home.
Case 2
A 28 year-old woman, who was diagnosed to have Insulin Dependent Diabetes mellitus (IDDM) for 6 years, was recently diagnosed with Systemic lupus erythema-tosus (SLE) a month ago in which she was started on prednisolone. However, two weeks later she presented with swelling in the right neck. The swelling was associated with dysphagia, odynophagia and fever. However, there was no shortness of breath or stridor. She gave a history of a right retropharyngeal abscess four years prior to the present condition during which drainage was performed. Clinically she was febrile, with a temperature of 390C on ad-mission. Neck examination revealed a ten-der swollen ill-defined area involving the superior part of anterior triangle of the right neck. The skin overlying it was inflammed and tender. There was trismus and the oral cavity showed bulging of the right pharynx-geal wall with pus noted. She was started on intravenous amoxicillin-clavulanic acid and metronidazole. Contrast enhance CT scan of the neck demonstrated multilo-culated, parapharyngeal and retropharyn-geal abscesses of the right neck with cervical lymphadenopathies (Figures 2a and 2b). She underwent incision and drainage on the second day of admission. Culture studies revealed Klebsiella spp. sensitive to amoxicillin-clavulanic acid. Microbiological culture for tuberculosis was negative. The patient made a rapid recovery and was discharged home after six days.
DISCUSSION
The parapharyngeal space occupies an in inverted pyramidal area bounded by multiple components of the fascial system. The inferior limitation of this space is the greater cornua of the hyoid bone. The superior margin of the space is the skull base. Its medial border is formed by the lateral pharyngeal wall (ie, the superior pharyngeal constrictor and the tonsillar fossa). The posterior border is formed by the prevertebral fascia. The lateral border is the ramus of the mandible and the deep lobe of the parotid (Amar et al 2004). The anterior boundary is the pterygomandibular raphe. The parapharyngeal space can be subdivided into two compartments by the fascia of the tensor veli palatine muscle which runs obliquely through the parapharyngeal space from the eustachian tube and styloid process to its insertion on the lateral pterygoid plate (Myers et al 1997).
The internal maxillary artery, inferior alveolar nerve, lingual nerve, and auriculo-temporal nerve comprise the pre-styloid compartment. Infections in this compartment often give significant trismus. The post-styloid compartment contains the carotid sheath (carotid artery, internal jugular vein, vagus nerve) glossopharyn-geal, hypoglossal nerves, sympathetic chain and lymphatics. It also contains the accessory nerve, which is somewhat protected from the pathologic processes in this region by its position behind the sternocleidomastoid muscle.
An odontogenic infection can cause a parapharyngeal abscess. It usually spread contiguously from the mandible or maxilla into the sublingual, submandibular or masticatory spaces and then spread into the parapharyngeal space directly. The most common symptoms of a parapharyn-geal abscess are neck pain, odynophagia, dysphagia,neck swelling, fever, and trimus. Lateral pharyngeal wall medializa-tion is the most common presenting sign in parapharyngeal abscesses (Bottin et al 2003). Both the patients presented with progressive painful neck swellings, asso-ciated with odynophagia, dysphagia and trimus.
Diabetes Mellitus (DM) is the most common systemic disease associated with parapharyngeal abscesses (Sethi et al 1991, Huang et al 2004, Bottin et al 2005). It has been established that lipopolysa-charide by bacteria and infection, mediate up regulation of cytokines synthesis. As shown in case 2, she was diagnosed to have IDDM six years ago, and she also gave a history of the retropharyngeal abs-cess, which was treated surgically. Her immune-compromised state further deterio-rated after she was treated with predniso-lone for her Systemic Lupus Erythematous (SLE). Chronic hepatitis was also found one of the commonly associated with para-pharyngeal abscess (Bottin et al 2005). Our first patient has thalassaemia major, underwent splenectomy and just recently diagnosed tobe a hepatitis C carrier. This makes the patient more susceptible to infection.
Laboratory investigations usually reveal-ed an elevated white blood count as in our patients, except for patients with HIV infection or AIDS (Shashinder et al 2007). Bacteriologic pattern of parapharyngeal abscess is usually a mixed growth, which includes anaerobes and aerobes. Strepto-coccus viridians were the most commonly isolated organisms in the non-diabetic patients, consistently high with rate of odontogenic infections. Klebsilla pneumo-niae was the most common organisms in diabetic patients (Huang et al 2005). In our patients, Klebsiella spp. was cultured. Broad-spectrum intravenous antibiotics should be started as soon as the diagnosis is suspected, because of the wide spec-trum nature of the involved microor-ganisms. The chosen antibiotics should cover the suspected bacteria and later can be modified according to clinical response based on bacteriological culture and sensitivity results. Discussion with the microbiologists is important to decide the choice of antibiotics, if the patients do not respond to the initial antibiotic.
Contrast-enhanced CT scans (CECT) is the gold standard in the evaluation of deep neck infections. CT scans provides valuable information for the site and the extent of infection. Abscesses were seen as low-density lesions with rim enhance-ment, occasional air fluid levels, and locu-lations (Bottin et al 2003). We considered CECT to be part of the routine invest-tigation. CT scan of the chest may be helpful if extension of abscess into the mediastinum was suspected. Otopanto-gram provide useful information in para-pharyngeal abscess of odontogenic origin (Bottin et al 2003).
The conventional method of surgical approach for the parapharyngeal space incision and drainage is through an external skin incision made about two finger breath below the mandible. The sternocleidomastoid muscle and great vessels was retracted posteriorly. The parapharyngeal space was entered just anterior to the posterior belly of the digas-tric and under the submandibular gland. Blunt dissection is used to break up any loculations (Amar et al 2004). The wound is left opened for continued drainage and dressing. We used this method in mana-ging our patients in view of better pus collection and ease of dressing.
Another method is via the intraoral approach. This procedure is performed under general anaesthesia. The Boyle’s mouth gag is placed in the patient’s mouth. The mouth is opened to obtain adequate exposure of the oropharynx. The lateral pharyngeal wall is palpated intraorally, or sometimes bimanually to localize the abscess. Once localized, an 18-gauge needle is inserted transorally through the lateral pharyngeal wall and into the abscess cavity. The then pus is aspirated and incision made in the overlying mucosa. The whole dilatation with a large clamp is performed in a longitudinal manner. This wound is left opened for several operative days to allow continued drainage of the abscess into the oropharynx (Amar et al 2004). It is a safe and effective procedure, provided the CT scan obtained preope-ratively shows the abscess is located medial to the great vessels of the neck (Amar et al 2004).
Duque reported another surgical intervention whereby intraoperative ultra-sound is used during any external ap-proach to the parapharyngeal space abs-cess when the abscess is difficult to identify with standard anatomic dissection (Duque et al 2007).
Feeding should be addressed in view of prolonged course of the disease, which needs nutritional support by nasogastric tube feeding. Tracheostomy may be an option in cases of difficult intubations or incidental rupture of the abscess (Alaani et al 2003). Both of our patients were nursed in HDU for closed monitoring of the general condition. In case 1, she developed acute pulmonary edema. She had aggressive treatment in HDU and was transferred to medical ward on day 4 post operation. Delay in treatment of parapharyngeal abscesses can result in life threatening complications such as airway obstruction, mediastenitis, vascular complication, septi-cemia and mortality.
CONCLUSION
Even though the advent of the antibiotic has dramatically decreased the incidence of deep neck infection, they remain pre-valent especially in immune-compromised patient. Early and aggressive management of parapharyngeal abscess can prevent major complications such as mediastinitis, vascular complications, septicaemia, retro-pharyngeal abscess mortality. Contrast en-hanced CT scans has preoperative diagnostic value in parapharyngeal abscess and surgical intervention remains the treat-ment of choice.