Fetal micro and macroglossia – Defining normal fetal tongue size

Fetal micro and macroglossia – Defining normal fetal tongue size

REVIEWED BY Lakshmi Sanal | ASA SIG: Women's Health

REFERENCE | Authors: Koren N, Shust‐Barequet S, Weissbach T, Raviv O, Abu Snenh S, Abraham E, Cahan T, Eisenberg V, Yulzari V, Hadi E, Adamo L, Mazaki Tovi, S, Achiron R, Kivilevitch Z, Weisz B & Kassif E

WHY THE STUDY WAS PERFORMED

Abnormal fetal tongue size is a phenotypic feature of various significant congenital syndromes and conditions including Down syndrome, Beckwith-Wiedemann syndrome, Pierre-Robin sequence, Simpson-Golabi, oromandibular limb hypoplasia, mucopolysaccharidoses, chromosomal abnormalities, and more. Tongue anomalies may present as an isolated finding and, occasionally, it may be the only presenting prenatal feature of a genetic syndrome. Due to lack of a published comprehensive fetal tongue growth curve throughout pregnancy, microglossia and macroglossia were perceived subjectively. The main objective of the study was to establish a contemporary fetal tongue nomogram and a Tongue Centile Calculator, which assists in determining normal fetal tongue dimensions (length, width, circumference, and area) between 13 and 40 weeks of gestation and to examine the clinical value of tongue measurement in suspected or confirmed pathologic cases.

HOW THE STUDY WAS PERFORMED

A prospective cross-sectional study was undertaken in singleton pregnancies. Well-established dates based on CRL measurements in dating scans and fetal weight between 10th and 90th percentiles were the applied inclusion criteria. Fetal malformations, genetic aberrations and conditions compromising fetal growth were excluded from the study. Fetal tongues were measured by trained sonographers, using a combination of transvaginal and transabdominal approaches pertaining to the gestational age and the highest quality image was selected. Image acquisition of the tongue was obtained in an axial plane, in supine fetal position, between the maxillary alveolar ridge and the mandibular alveolar ridge. The definition of terminal sulcus improved the clear identification of the posterior tongue margin. Intra- and interobserver variability was assessed. Tongue length, width, area, and circumference 1st to 99th percentiles were calculated for each gestational week. Based on the normal tongue size charts, the researchers created a Tongue Centile Calculator. A pilot study was also done for reproducibility of the measurements on fetuses between 13 and 40 weeks. Statistical analyses were performed using SPSS statistical package version 20 for Windows and Microsoft Excel 2016 software. All tests were 2-tailed, and a p-value of < .05 was considered statistically significant.

“Objective tongue measurement could assist distinguishing a truly pathologically sized tongue from a normal sized tongue erroneously judged abnormal.”

WHAT THE STUDY FOUND

A cubic polynomial regression model best described the correlation between tongue size and gestational age. The correlation coefficient (r2) was 0.934, 0.932, 0.925, and 0.953 for tongue length, width, area, and circumference, respectively (P < .001). Intra- and interobserver variability had high interclass correlation coefficients (> 0.9). Using the new charts, Koren et al. were able to identify 2 cases of macroglossia, subsequently diagnosed with Beckwith-Wiedemann, and 4 cases of microglossia, 3 associated with Pierre-Robin sequence, and 1 associated with persistent buccopharyngeal membrane. This established that these nomograms are an essential tool for distinguishing normal from pathological-sized tongues associated with syndromes. The prospective study design with strict adherence to inclusion and exclusion criteria and relatively large sample size for each week effectively contributed to the quality of the nomogram.

RELEVANCE TO CLINICAL PRACTICE

Congenital tongue anomalies include growth abnormalities (macroglossia, microglossia/ hypoglossia), positional abnormalities (glossoptosis), and lingual lesions. These conditions can cause chronic speech impairment, feeding and respiratory difficulties, recurrent upper respiratory tract infections, and even life-threatening postnatal airway obstruction. Subjective tongue assessment is not reliable. Therefore, an objective evaluation of the tongue size helps in detecting fetal abnormalities and can aid in the management and counselling of affected pregnancies. These findings can contribute to the overall improvement of prenatal care.