INTRODUCTION It is not unusual to find a stone in the lacrimal sac during dacryocystorhinostomy (DCR). Although patients with dacryolithiasis often have a history of long-term intermittent epiphora, lacrimal sac distention, and/or partial obstruction of the nasolacrimal duct (NLD), dacryoliths are often only detected during DCR. The incidence of dacryoliths in the lacrimal sac of patients that undergo DCR ranges from 6.0-18.0%; however, the incidence of dacryoliths has not been evaluated in the general population. Unfortunately, most published studies on dacryoliths have included quite a small number of samples.
Canalicular concretions have long been associated with canaliculitis caused by actinomycotic infection. However, despite recent, significant progress, an understanding of the pathophysiology of lacrimal sac dacryoliths is still missing. Several predisposing factors have been suggested to contribute to the mechanism that gives rise to dacryolith formation. These factors include age (under 50 years old), sex (increased frequency in females), cigarette smoking, and previous occurrence of chronic dacryocystitis and primary acquired nasolacrimal duct obstruction (PANDO). Recent analyses have shown that dacryolith development may be related to lacrimal sac epithelial and NLD production of a broad spectrum of mucins and expression of two peptide members of the trefoil factor family (TFF), TFF1 and TFF3. Because dacryoliths occur at low frequency, few studies have focused on their composition.
In this study, the authors aimed to present findings from morphological, chemical, and mineralogic analysis of 86 dacryoliths.
MATERIALS AND METHODS A total of 967 primary EDCRs were performed at the Department of Otorhinolaryngology of the University Hospital of Ostrava and at the Department of Otorhinolaryngology of the Frydek-Mistek City Hospital between 1994 and April 2012. Only EDCRs performed for postsaccal stenosis/obstruction (832 procedures) were included in the study. Exclusion criteria were presaccal obstruction treatment, revision EDCRs, and incomplete follow-ups.
The study was performed in accordance with the Declaration of Helsinki, Good Clinical Practice, and applicable regulatory requirements. Written consent was obtained from all patients before the initiation of surgery and dacryolith analysis.
Among the group of 832 EDCRs, 86 stones of the lacrimal sac (dacryoliths) were found, including 61/86 (70.9%) in women and 25/86 (29.1%) in men. Clinical information was obtained from patient medical records, including the involved side, the etiology of the nasolacrimal duct (NLD) obstruction, the outcome of EDCR at one year after surgery, the size of the dacryolith, and data from dacryolith analysis. The investigators also performed infrared spectrometry, amino acid analysis, and imaging and morphological analyses with a scanning electronic microscope. The association with cigarette smoking was not examined.
Infrared spectroscopy The authors examined the dacryoliths with Fourier transform infrared spectrometry (FTIR; IMPACT 410, fy Nicolet) and a tableting method with potassium bromide (KBr). Evaluations were performed with OMNIC software, and the obtained spectra were compared with a library of spectra from kidney stones.
Amino acids analysis Proteins in the samples (≤ 20 mg) were hydrolyzed with hydrochloric acid \[1,2\]. Then, 1 mL of distilled water was added, the solution was filtered, then evaporated at 90 ºC under nitrogen, and the residue was dissolved in 2 mL of 1% aqueous NaOH. An aliquot (\~0.5 mg of the initial sample) was transferred to another tube, the volume adjusted to ± 100 µL with 1% NaOH, and a derivatization was performed with ethyl chloroformate (4). Next, gas chromatography in tandem with mass spectrometry with a 7890A and MSD5975C (Agilent) was performed, equipped with a 30-m, VF-17ms capillary column (0.25 mm × 0.15 μm; CP8981 from HPST, Praque). Samples were run at temperatures ramped from 60 to 300 ºC at a rate of 6 ºC /min; split injection (10:1) was employed. Electron impact (EI) mass spectrometry detection at 70 eV was performed at temperatures of 230 ºC for the ion source, 250 ºC for the transfer line, and 150 ºC for the quad. We performed full-scan analyses with a helium-carrier gas flow of 1.2 mL/min.
Imaging and morphological analysis Morphological analyses were performed with a scanning electron microscope (QUANTA FEG 450, FEI Company, WA, USA). An electron microprobe with an energy dispersive detector (EDS) was used for the elemental analysis of the organic matrix of the stone and for the analysis of fine inorganic particulates in the stone.
Statistical analysis For statistical analysis, binomial confidence intervals (CI) for the success rates at the 95% CI were calculated. The two-sample t-test and X2 test were used to evaluate differences in age, sex, and surgical success between groups I and II; p\<0.05 was considered statistically significant.
