Nasal Mucociliary Motility: New Forensic Tool for Estimating Time Since Death

After attending this presentation, attendees will understand thepotential contributions of postmortem investigation of nasal mucociliarymotility in time of death estimation.This presentation will impact the forensic science community byemphasizing the potential role of nasal scraping that could become aroutine procedure in estimating time-since-death.Postmortem interval (PMI) estimation is one of the most difficultissues in forensic medicine. Time-of-death is usually appreciated byrecognizing early postmortem changes to the body prior to the onset ofgross decomposition phenomena: algor mortis, rigor mortis, and livormortis.The study of these physical processes is strictly connected to theoperator’s subjectivity hence it can be source of confusion in estimatingPMI. Moreover these body changes can be altered by several internaland external factors: body temperature at death time, subcutaneous fat,muscular mass, clothes, environmental temperature, humidity, andventilation.There have been many proposed innovative methods in attempts toavoid this trouble defining PMI objectively as possible. The goal ofthese new techniques is to find a link between PMI and objectivelydetectable values such as infrared tympanic thermography, skinfluorescence, electrolyte concentration in cerebro-spinal fluid,pericardial fluid or vitreous humor. All these samples, on the other hand,present practical difficulties in performing and require invasive methodsand long time waiting.Some studies have been published about nasal scraping role inclinical practice (ciliary dyskinesia, NARES, allergic rhinosinusitis), butno studies have never been performed in cadavers for PMI estimation.A study concerning the examination of ciliary motility as residuallife phenomenon, realizing a study on time of death evaluation using anew, rapidly available requiring substrate: nasal mucosa is presented.Nasal mucosa is composed by numerous cell types (globet cells,basal cells, ciliated and not ciliated cells) and can be easily obtained bynasal scraping, a technique commonly used in otolaryngology; it consistsof a curette crept on nasal mucosa and cells picked up in this way arethen observed.From June 2009 to June 2010, nasal scraping in 70 cadavers wasperformed. Age ranged from 24 to 95 years and the cause of death wasmost frequently due from ischemic cardiopathy, septic shock, and caraccident. The only exclusion criteria of this study was nose bleeding.A specimen of ciliated epithelium was obtained by scraping fromthe middle third of the inferior turbinate with a spoon-shaped nasal probe(Rhinoprobe). An in vitro evaluation of ciliary movement wasperformed. Ciliary beat frequency (CBF) was analyzed by phasecontrastmicroscopy. Three different samples at different postmortemintervals were carried out: between 4 and 6 h (T1), between 10 and 12 h(T2) and after 24 h (T3). Then CBF (beat number/second) was classifiedin: present (3-4/sec), hypo-valid (1-2/sec) and absent.Results demonstrated that, except for those cases which showedfungal or bacterial infections, at T1 motility was present in the majorityof cases; at T2 motility was still present, but it was hypo-valid in a higherpercentage. Ciliary activity was absent at T3. It is believed that all thesefindings can be explained with progressive metabolic reserves lowering:the more time passes after death, the more ciliated cells loose energeticsubstrates for ciliary motility.In conclusion, mucociliary motility seems to be linked to PMI andthus nasal scraping can be considered as a new, easy, cheap, and efficientobjective tool in detecting PMI; further studies are required.