The tonsils are the bilateral areas of lymphoid tissue behind the palatoglossal arch.
More precisely called the palatine tonsils, they form part of Waldeyer’s tonsillar ring, which includes the pharyngeal tonsils (adenoids), tubal tonsils (the opening of the eustachian tube) and the lingual tonsils (at the base of the tongue).
Tonsillitis is an inflammatory condition of the palatine tonsils secondary to bacterial or viral infection. These infections are common, especially in children. They affect around 10 per cent of the population per year, and in most cases are not serious. However, some patients are prone to severe recurrent infections which can lead to considerable morbidity. They are rare in under-two-year-olds, but common in those aged two to eight years.
Inflammation leads to local pain and, if severe, odynophagia. Severe swelling can lead to dysphagia and airway obstruction, which is an indication for hospitalisation. The patient may also complain of malaise and lethargy.
Some 30 per cent of infections are bacterial, of which the most common and significant is group A beta haemolytic streptococcus (GABHS). Other bacteria include Haemophilus influenzae and anaerobes such as Bacteroides fragilis.
Viral causes include Epstein-Barr virus, which accounts for 20 per cent of cases, and herpes simplex virus.
Distinguishing bacterial from viral causes is difficult. The proposed Centor Criteria (see box) have a positive predictive value of 50 per cent and a negative predictive value of 80 per cent.
Throat culture is of limited value as a negative culture does not rule out GABHS. Also, 40 per cent of carriers are asymptomatic and isolation of GABHS does not correspond well with serological evidence of infection.
Complications secondary to GABHS include scarlet fever, rheumatic fever, septic arthritis and glomerulonephritis.
Because the incidence of acute rheumatic fever is low in the UK, it is argued that watching and waiting is preferable to diagnosis and treatment.
Complications of tonsillitis include peri-tonsillar abscess and, rarely, infection spreading into deeper tissue and jugular vein thrombophlebitis. Peri-tonsillar abscess should be considered when the tonsillitis does not improve, and foul breath are present.
Antibiotics are indicated if GABHS infection is the cause. The antibiotic of choice is phenoxymethylpenicillin for 10 days. Where compliance is a problem use IM penicillin.
Clindamycin may be of use in those who are refractory to treatment, because it has superior tissue penetration. If anaerobes are suspected the addition of metronidazole would be useful.
Adequate hydration and control of pyrexia with paracetamol are indicated. There is weak evidence to support the use of oral benzydamine. Where monoinfectious nucleosis causes tonsillar swelling, steroids and possible gamma globulins are also indicated.
Aciclovir is indicated in herpes simplex virus tonsillitis. Peri-tonsillar abscesses rarely drain spontaneously and surgical intervention is required.
Tonsillectomies are indicated if tonsillitis is proven, has occurred more than five times a year for more than a year and is functionally disabling.
Patients should be made aware that there is a 0.5–3 per cent complication rate, that pharangeal and palatine tonsils are usually removed together, that tonsillitis can recur and that surgical treatment will not prevent sore throat.