Oral mucosal irritating plant ingestion in Hong Kong: epidemiology and its clinical presentation

Transcription

1 Hong Kong Journal of Emergency Medicine Oral mucosal irritating plant ingestion in Hong Kong: epidemiology and its clinical presentation CT Pang, HW Ng, FL Lau Objective: To study the local epidemiology and clinical presentation after ingestion of oral mucosal irritating plants. Methodology: Cases presenting with immediate oral mucosal irritation after plant product ingestion from July 2005 to June 2009 were retrieved from the Hong Kong Poison Information Centre's clinical database. Their clinical features and management were reviewed. Results: Thirty cases were retrieved and analysed, including 14 males and 16 females. Poisoning occurred all year round with no seasonal predilection. Vomiting and dysphagia were the two most common symptoms other than immediate oral mucosal irritation. Half of the cases could be managed with symptomatic treatment and discharged after a few hours of observation. Six patients presented with angioedema and were managed initially with the use of intravenous steroid, antihistamine and with or without adrenaline. Urgent airway assessment with laryngoscope was performed in 3 patients. No patient required endotracheal intubation. Conclusion: Oral mucosal irritating plant ingestion is not uncommon in Hong Kong. Its clinical feature can mimic angioedema on presentation. Immediate and localized oral mucosal symptoms after plant product ingestion are the key to diagnosis. (Hong Kong j.emerg.med. 2010;17: ) Keywords: Calcium oxalate, poisoning Correspondence to: Pang Chi Tak, MBChB, MRCSEd United Christian Hospital, Hong Kong Poison Information Centre, K3A, 130 Hip Wo Street, Kwun Tong, Kowloon, Hong Kong pangct1@ha.org.hk Ng Hon Wah, FHKCEM, FHKAM(Emergency Medicine) Lau Fei Lung, FRCP, FHKAM(Emergency Medicine) Introduction Oral mucosal irritation occurring after the ingestion of calcium oxalate raphide containing plants is well documented in the literature. The most commonly encountered plants belong to the Araceae family, Alocasia genus. 1,2

2 478 Hong Kong j. emerg. med. Vol. 17(5) Nov 2010 Species in Araceae are often found to contain calcium oxalate needle-shaped crystals or raphides. The clinical toxidrome after calcium oxalate exposure is mainly due to local irritation of the upper aerodigestive tract. The most common clinical manifestation is immediate throat and oral numbness and irritation after the ingestion. Rarely, it can cause upper airway oedema and obstruction in severe cases for which endotracheal intubation is indicated for airway protection. 3 This retrospective study aimed to review the mode of presentation of patients after oral exposure to mucosal irritating plants, the epidemiology, causative agents and the clinical course when treated in the emergency department. Subjects and methods All poisoning cases collected by Hong Kong Poison Information Centre (HKPIC) from July 2005 to May 2009 were retrieved from its database for analysis. The HKPIC was established in July Its main functions include the provision of poison information and toxicology management advice to health care professionals in Hong Kong. The centre also serves to collect poisoning data for toxico-vigilance, training and poisoning prevention. Cases with upper aerodigestive tract irritation after plant product ingestion and with a discharge diagnostic code of poisoning in the emergency department were included for analysis. Patient's clinical notes (emergency department notes, discharge summaries and subsequent management notes) were reviewed via the electronic patient record (epr) system of the Hospital Authority of Hong Kong. The cases were analyzed for their basic demographic features e.g. age and sex, plant product involved, symptoms upon presentation, subsequent clinical course, length of stay in the hospital and significant complications. Results There were 31 cases meeting the study criteria. One patient was excluded for incomplete clinical data. The study included a total of 14 male and 16 female patients. Age ranged from 20 to 65 years old. There was no seasonal predilection as the poisoning occurred all year round. According to the food history from the patients, the most common culprit was taro (wild taro / false taro, 21 cases). They were wild plants picked in hillside areas and mistaken to be edible. Other offending plant products included water spinach (, 5 cases), celery cabbage (, 1 case), flowering Chinese cabbage (, 1 case) and watercress (, 1 case), that were either purchased locally from the market or consumed in local restaurants. These vegetables were not supposed to contain any oxalate raphide or other irritants, and it was postulated that contamination or misidentification with other plants containing oxalate raphides could be the cause. Besides intake as food product, one patient chewed a piece of herbal remnant in an herbal broth and then complained of immediate oral swelling and numbness. The herbal remnant was sent to the Toxicology Reference Laboratory (TRL) for sample analysis. Oxalate raphide crystals were found by microscopy and the unused herb sample was identified as Alocasia macrorrhiza ( ). There were no botanical investigations done in the rest of the cases. Other than immediate irritative symptoms (pain and numbness) over the upper aerodigestive tract (oral cavity and throat), vomiting was the commonest presenting symptom (7 patients, 23%), and it was usually self-limiting. Five patients presented with dysphagia or odynophagia (17%). Another five patients presented with shortness of breath (17%), which was transient and their oxygen saturations on room air were all normal. Two other patients presented with chest pain (7%). Congestion and oedema of the lips and oral mucosa were the commonest finding during physical examination (21 patients, 70%). Drooling of saliva was found in 4 patients (13%). The physical examination was unremarkable in 9 patients (30%) The clinical courses of these 30 patients were summarised in Figure 1. Twenty-four out of the 30

3 Pang et al./oral mucosal irritating plant ingestion 479 patients were managed conservatively. Three patients were discharged with oral analgesic immediately after consultation in the emergency department while 18 others were given symptomatic treatment in the emergency department (e.g. Gastrocaine, panadol, or mouth rinse). Three patients either disappeared or discharged against medical advice, after consultation. Of the 18 patients receiving observation in the emergency department after initial treatment, 13 (43%) patients could be discharged within 6 hours, while 4 others stayed up to 12 hours for symptomatic control. One patient stayed for 1.5 days for prolonged symptoms. Six patients (20%) were treated actively as angioedema in the emergency department. Intravenous steroid and antihistamine were used in 5 cases, and subcutaneous adrenaline in 2 cases. Urgent airway assessment by otorhinolaryngology surgeon was conducted in 3 cases. All examinations showed patent airway with mucosal swelling limited to the oral mucosa only. None of the cases required endotracheal intubation. Four patients were admitted to the hospital with median length of hospital stay of 2 days. One case complicated by Mallory Weiss tear of the oesophagus after swallowing a piece of wild taro was admitted for 12 days. Two were observed in the Observation Ward but one discharged against medical advice after 4 hours. Discussion Oxalate raphides are bundles of tiny needle-like oxalate crystals. They are contained in specialised cells of the plant which are able to fire raphides out of the cell upon stimulation. This leads to mechanical injury and painful microtrauma on skin or mucosal surface. Sometimes, proteolytic enzyme is also involved which increases local painful irritation. 1,4-6 The most commonly encountered plants belong to the Araceae family, Alocasia genus, but they can also be found in some common household plants like Dumbcane ( ) and Narcissus bulbs DAMA=discharge against medical advice; ED=emergency department; ENT=ear, nose and throat; IV=intravenous Figure 1. Clinical course of the 30 patients.

4 480 Hong Kong j. emerg. med. Vol. 17(5) Nov 2010 ( ). They are able to synthesize calcium oxalate in their stems and leaves, and accumulate them in high concentration to form insoluble oxalate raphides. 7 The clinical toxidrome is mainly local irritation of skin and mucosal surface. The most common clinical manifestation is throat and oral irritation and numbness immediately after ingestion. Other symptoms include difficulty in speaking, excessive salivation and lip swelling. Ocular exposure may produce chemical conjunctivitis, and even corneal abrasion. 8 Treatment is mainly symptomatic relief. Oral rinse and the use of simple oral analgesic would suffice in most situations, and symptoms usually begin to subside in a few hours. 4,7 Swallowing of the plant product can cause more serious complication than tasting such as injury to the oesophageal mucosa. One of our patients had sustained a Mallory Weiss tear after swallowing one piece of wild taro and he needed to stay for 12 days in the surgical unit subsequently. Around 80% of the patients were treated conservatively and could be discharged after a few hours of symptomatic treatment. This implies that symptomatic treatment is the mainstay, and a short period of observation would suffice in the majority of the cases. It is important to differentiate oral mucosal swelling caused by irritant plant exposure from angioedema. Although the initial presentation of the two conditions may be similar, clinical history is the key for differentiation. Oral irritating symptoms with pain occur almost immediately in plant product ingestion. However, in angioedema, time is usually required for allergic response to develop. Angioedema involves a systemic response and rarely affects the mouth and throat only. So a history of plant product ingestion and the time frame of occurrence of mucosal symptoms can provide a useful hint for formulating the diagnosis. Furthermore, food allergy is relatively uncommon in adults (<3%) when compared with children (6-8%). 9 Immediate throat pain and swelling in an adult, after plant product ingestion, should alert the physician to the possibility of calcium oxalate raphide poisoning, whereas acute food allergy or angioedema is less likely. In this study, the incidence of irritant plant exposure had no seasonal predilection. The offending plant products were not restricted to the Araceae family. Our explanation could be contamination or misidentification of plant products during harvesting or processing. Hence, the absence of Araceae plants in the food history could not reliably exclude the diagnosis. Limitations The major limitation of this study was under-reporting of the condition. As the clinical effect would be mild, we believed that the majority of patients would not present themselves to the emergency department for medical attention. Should they have sought medical advice from the emergency department, only simple symptomatic treatment would be given because of the mild symptoms and these cases would not be reported to the HKPIC. Out of these 30 cases, plant product identification was sought for one case only. In all other cases, the diagnosis remained clinical. Although identification could allow a more accurate diagnosis, it would not affect the treatment strategy in the emergency department. Conclusion Oral mucosal irritating plant exposure is not uncommon in Hong Kong. There are various causes for exposure e.g. contamination, misidentification and intentional misuse. Immediate oral irritative symptoms with pain and numbness after plant product ingestion are the hallmark for diagnosis. The condition can sometimes mimic angioedema due to severe mucosal swelling, but can be differentiated from angioedema by immediate symptom onset and the lack of systemic response during patient evaluation. Emergency airway assessment and intervention is rarely necessary. Symptomatic relief is the mainstay of treatment and most patients can be discharged after a few hours of observation.

5 Pang et al./oral mucosal irritating plant ingestion 481 For the treatment approach, we support immediate mouth rinse using either water or milk to remove the calcium oxalate crystals inside the oral cavity. The symptoms can be relieved by using simple analgesic and antihistamine, though evidence based treatment is not yet available. References 1. Lin TJ, Hung DZ, Hu WH, Yang DY, Wu TC, Deng JF. Calcium oxalate is the main toxic component in clinical presentations of Alocasia macrorrhiza (L) Schott and Endl poisonings. Vet Hum Toxicol 1998;40(2): Zhong LY, Wu H. Current researching situation of mucosal irritant components in Araceae family plants. Zhongguo Zhong Yao Za Zhi 2006;31(18): Watson JT, Jones RC, Siston AM, Diaz PS, Gerber SI, Crowe JB, et al. Outbreak of food borne illness associated with plant material containing raphides. Clin Toxicol (Phila) 2005;43(1): Gardner DG. Injury to the oral mucous membranes caused by the common houseplant, Dieffenbachia. A review. Oral Surg Oral Med Oral Pathol 1994;78(5): Rauber A. Observations on the idioblasts of Dieffenbachia. J Toxicol Clin Toxicol 1985; 23(2-3): Herbert DA. Stinging crystals in plants. Science 1924; 60(1548): Flomenbaum NE, Goldfrank LR. Goldfrank's toxicologic emergencies. 8th ed. New York: McGraw- Hill; p Tang EW, Law RW, Lai JS. Corneal injury by wild taro. Clin Experiment Ophthalmol 2006;34(9): Lack G. Food allergy. N Eng J Med 2008;359(12):