Synopsis of key findings
All cases were in young children under the age of five years despite the centre treating children with ALL up to the age of 17 yrs.
In all seven cases, and similarly to the other cases we identified in the literature, symptoms occurred often during the induction period within a few doses of vincristine 1,4,5, thus suggesting toxicity may not necessarily be dose dependant.
All seven patients had symptoms of hoarse voice, stridor and increased work of breathing. Due to the complex nature of children undergoing chemotherapy, it is therefore important not to attribute these symptoms to more common problemssuch as croup or a lower respiratory tract infection. It is therefore advisable to have a low threshold for referral to an ENT specialist for awakebedside examination of the larynx4. Bilateral cord paralysis can be an acutely life threatening condition if missed and prompt diagnosis is essential. Four of seven of the cases had preceding potential signs of neuropathy, (table 1) however, in three children stridor was the first vincristine related symptom therefore vcp should be considered in any child being treated with vincristine who presents with hoarse voice, stridor or breathing difficulties.
None of the patients were on any medications such as azole antifungals that are known to increase the toxicity of vincristine including vcp6,7.
In our case cohort all patients received some further doses of vincristine yet still had full vocal cord recovery within a year. The risk of further vincristine is of permanent need for tracheostomy but this must be traded against the risk of leukaemia relapse from inadequate therapy.. The aim should be to deliver vinca alkaloids in as close to target dose as possible during the intensive phases of therapy but can be more safely omitted in the continued maintenance phase. We therefore suggest a potential management algorithm in figure 1.