Following the hospitalization of a 6-month old baby for CNS disorders then coma, an intoxication with amitriptyline (AMI) was highlighted (blood concentrations : AMI = 99.4μg/L and nortriptyline (NOR) = 154μg/L). Complimentary investigations suggested a shaken baby syndrome. Given the family context, a judge ordered hair tests for both the child and his parents to document drug exposure. The aim of this case is to present the interest of hair analysis when poor evidence is available.

For the child, we collected a strand of hair (4cm of length, 60mg) during the acute intoxication (To) and a second strand 5 weeks after (5cm of length, 82mg). Three months after the acute intoxication of the baby, samples of hair were collected from mother (strand of 22cm of length, 1951mg, and black color) and from father (strand of 5cm of length, 98mg, and gray color).

After decontamination with 5-min dichloromethane wash, strands were segmented and finely cut with scissors. 3ng of methadone-D3 (internal standard) were added to 10mg of sample, followed by incubation 12h at 55°C in methanol. After evaporation, each dry residue was dissolved in 100μL of mobile phase (water + 0.2% ammonium hydroxide) in order to quantitate AMI and NOR by LC-MS/MS. 50μL of sample was injected, an online sample clean-up was performed on an Oasis HLB column (Waters^®), and the chromatographic separation was performed on an analytical column, Atlantis^® dC18 3μm 2.1x150mm (Waters^®). Quantitation was performed using positive ionization mode on an API4000 (ABSciex^®) and was based on two monitored transitions : 278,2m/z -> 91m/z; 278,2m/z -> 105,1m/z and 264,3m/z -> 233,1m/z ; 264,3m/z -> 91,1m/z, for AMI and NOR respectively. The cut off level was fixed at 0.01ng/mg for AMI and NOR.

For both parents all hair segments tested negative. For the baby, the results are summarized in the following table:
Strand at To (without decontamination)Strand at T 5 weeks (with decontamination)Segment numberDistance/root (cm)AMINORSegment numberDistance/root (cm)AMINOR(ng/mg)(ng/mg)10 at 0.56.98.110 at 0.71.23.620.5 at 1.06.67.120.7 at 1.21.44.031.0 at 2.59.09.031.2 at 1.91.23.342.5 a 4.09.78.941.9 at 2.50.792.352.5 at 3.00.651.863.0 at 3.60.591.573.6 at 50.551.3

High concentrations in all segments of the first strand of the child were in accordance with recent exposure and potential contamination by sweet. Maximal concentrations in segment number 2 of the second strand confirmed the acute intoxication. The presence of AMI and NOR in all segments of the second strand provided the proof of chronic exposure during several months before hair collection with regular increase. The profile of increasing concentrations revealed by segmentation allows the exclusion of in utero exposure.