What Is the Dimple on a Newborns Baby Back Mean

Korean J Pediatr. 2018 Jun; 61(six): 194–199.

Outcome of ultrasonographic imaging in infants with sacral dimple

Jin Hyuk Choi, Dr.,¹ Taekwan Lee, MD,^one Hyeok Hee Kwon,^two Sun Kyoung You, Doctor, PhD, ^three and Joon Won Kang, Physician, PhD ^{1, 2, 4}

Jin Hyuk Choi

¹Department of Pediatrics, Chungnam National Academy Hospital, Chungnam National University School of Medicine, Daejeon, Korea.

Taekwan Lee

¹Section of Pediatrics, Chungnam National University Hospital, Chungnam National University School of Medicine, Daejeon, Korea.

Hyeok Hee Kwon

²Department of Medical Scientific discipline, Chungnam National University School of Medicine, Daejeon, Korea.

Sun Kyoung Yous

³Section of Radiology, Chungnam National University Hospital, Daejeon, Korea.

Joon Won Kang

¹Department of Pediatrics, Chungnam National University Infirmary, Chungnam National Academy School of Medicine, Daejeon, Korea.

²Department of Medical Science, Chungnam National University School of Medicine, Daejeon, Korea.

⁴Brain Research Institute, Chungnam National University School of Medicine, Daejeon, Korea.

Received 2017 Sep five; Revised 2017 Oct 25; Accepted 2017 October 31.

Abstract

Purpose

Sacral dimples are a mutual cutaneous anomaly in infants. Spine ultrasonography (USG) is an constructive and prophylactic screening tool for patients with a sacral dimple. The aim of this study was to determine the clinical manifestations in patients with an isolated sacral dimple and to review the direction of spinal cord abnormalities identified with USG.

Methods

Nosotros reviewed clinical records and collected data on admissions for a sacral dimple from March 2014 through February 2017 that were evaluated with spine USG by a pediatric radiologist. During the same period, patients who were admitted for other complaints, but were found to have a sacral dimple were likewise included.

Results

This study included 230 infants under 6-months-old (130 males and 100 females; mean age 52.eight±42.half dozen days). Thirty-i infants with a sacral dimple had an echogenic filum terminale, and 57 children had a filar cyst. Twenty-seven patients had a depression-lying spinal string, and only i patient was suspected of having a tethered cord. Follow-upwards spine USG was performed in 28 patients, which showed normalization or insignificant change.

Determination

In this study, all but one infant with a sacral dimple had benign imaging findings. USG tin be recommended in infants with a sacral dimple for its convenience and prophylactic.

Keywords: Babe, Lumbosacral region, Skin abnormalities, Ultrasonography, Diagnostic imaging

Introduction

Cutaneous lesions of the lower dorsum region could be associated with tethered string syndrome including hairy patches, subcutaneous lipomas, and dimples.1) A simple sacral dimple is less likely to be associated with tethered cord syndrome, but this is difficult to prove. It is not well known whether this is associated with other spinal string anomalies.

A sacral dimple was constitute in ane.8%–7.2% of newborn infants;2,iii,four) it is a common skin lesion that tin can easily be found in outpatient clinics or admission during neonatal periods. It has been reported that a dimple tin be seen equally a typical benign lesion when visible, less than 0.5 cm in size, and has one lesion located in the midline. Large, deep, and afar from the anus, hair, and of changed color may be associated with other diseases.iii,4,5) However, further test is necessary because the visual abnormalities cannot exist completely discriminated via visual examination.

Ultrasonography (USG) is a safe and price-effective screening method and is commonly used in infants with sacral dimples.half-dozen,7) It is a noninvasive screening method that does not risk radiation exposure in children, and does not crave sedation. In add-on, spinal USG performed at a young age is effective because it can acquire relatively accurate imaging compared to postossification. Despite its many advantages, in that location is a suggestion that USG is not required.eight) Currently, limited enquiry exists on the clinical significance of USG in sacral dimple in Korea. This study investigates the clinical features of the sacral dimple in patients with a sacral dimple, and evaluates the prevalence of accompanying diseases and the necessity of USG.

Materials and methods

ane. Patients

A retrospective review of clinical information and imaging findings (lumbar spinal USG and spine magnetic resonance imaging [MRI]) was performed for the records of 304 children who were diagnosed with a sacral dimple from March 2014 through to February 2017 in Chungnam National University Hospital. A USG was performed for all patients who visited for a sacral dimple. The USG findings of the patients who underwent the starting time US inside 6 months after their birth were analyzed.

Physical exam including pinnacle and weight were investigated at the kickoff visit. The birth history including gestational age, birth weight, and delivery method were examined. The clinical features of sacral dimple were adamant by examining the pilus, skin color, secretion, and altitude from the anus to the sacral dimple. Patients with grossly observed anal anomalies or masses, chromosomal anomalies, and multiple deformities were excluded. The flow diagram for enrollment was as drawn in Fig. 1. This study was performed with the approval of the Institutional Review Board of Chungnam National University Hospital (2017-01-022).

Menses diagram showing the enrollment of patients with a sacral dimple. CNS, key nervous system.

ii. Image technique and analysis

All spinal USG were performed by a single pediatric radiologist (SKY) with 5 years of experience using an IU-22 Philips ultrasound arrangement (Philips Healthcare, Bothell, WA, USA) with a linear-assortment probe (12-five MHz). A kyphotic curvature was created past placing the patient on a pocket-size pillow in a decumbent position and performing a midline scan over the spinous process. The Normal lumbar spine USG finding was as shown in Fig. 2A. We recorded the level of the tip of the conus medullaris (CM), the pulsation of CM or the nervus roots, the thickness and echogenicity of the filum terminale (FT), the presence of intraspinal mass, and normal variants including filar cysts and ventriculus terminalis.

Ultrasonography (USG) findings in patients. (A) Normal lumbar spine USG in a iv-day-onetime boy. Longitudinal USG shows normal anatomy of the spinal canal and its contents. (B) Low-lying spinal cord in a 4-solar day-quondam girl. (B1) Longitudinal USG shows the tip of the conus medullaris terminating at L3–4 disc space. (B2) Sagittal T2-weighted magnetic resonance imaging confirms the level of the conus medullaris at the L3–4 disc space. (C) Echogenic filum terminale. (C1) Prominent filum terminale in a 6-calendar month-onetime boy. Longitudinal USG shows hyperechoic filum terminale with normal thickness (about 1.3 mm). (C2) Thick filum terminale in a v-month-one-time boy. Longitudinal USG shows hyperechoic filum terminale with 2.2-mm thickness. (D) Filar cyst (pointer in D1 and D2) in a one-month-erstwhile boy. Longitudinal (D1) and transverse (D2) USG shows well-defined, thin walled, fusiform cyst below the tip of the conus medullaris.

The echogenicity of FT was compared to adjacent roots of the cauda equina. FT was considered thick when it measured more than than two mm on transverse and longitudinal US and was considered fibrous or lipomatous nature. We considered it every bit "prominent FT" when the thickness of the echogenic FT was less than 2 mm. If the tip of the CM was beneath the L2–3 disc space, this was considered low-lying spinal cord. Nosotros defined the isolated low CM as the tip of CM is seen at L2–3 disc space or the L3 vertebral body level without testify of tethering.9) The findings of boosted imaging including follow-up US or MRI were also recorded.

3. Statistical assay

Statistical analysis was performed using IBM SPSS Statistics ver. xx.0 (IBM Co., Armonk, NY, Us). Chi-square tests, and t examination were applied to the data to compare variables; P<0.05 was regarded statistically significant.

Results

1. Clinical characteristics

Of the 304 patients who underwent spinal USG, 230 patients (130 boys and 100 girls) who were younger than 6 months were included in the study (Fig. i). The mean historic period at first visit was 52.eight±42.6 days (range, 1–175 days), the mean superlative was 56.0±6.1 cm and the mean body weight was four.9±1.7 kg. In birth history, the mean gestational age was 38.5±ane.7 weeks, 29 patients were born as premature neonate. One hundred ninety patients were built-in at full term, and 1 patient was born at 42 weeks of gestational age. The mean nascence weight was 3.i±0.five kg, and 48% of the patients were delivered via cesarean section. About 65% of the patients visited hospital within 1 month of age (Fig. three). Xxx-nine patients (17.0%) had hair, and ii patients (0.nine%) had belch at the dimple region. Twenty patients (8.7%) had pare discoloration and vi had peel tag (2.vi%). The distance from the anal verge to the dimple was 2.14±1.01 cm (Table 1).

Historic period at first visit to the infirmary.

Table i

Patient profiles

Variable	Value
Demographic findings
Sex, male person:female	130:100
Age at visit (solar day)	52.eight±42.six (one–175)
Elevation (cm)	56.0±half-dozen.ane (42.0–72.2)
Weight (kg)	4.ix±1.7 (one.8–10.0)
Delivery history
Gestational historic period (wk)	38.5±one.7 (30–42)
Preterm (<37)	29 (xiii.2)
Term (≥37, <42)	190 (86.4)
Postterm (≥42)	1 (0.4)
Nascency weight (kg)	3.1±0.five (1.ane–4.5)
Delivery method, VD:C/S	119:100 (52.0:48.0)
Findings of sacral dimple
Hair	39 (17.0)
Discharge	two (0.ix)
Discoloration	20 (8.seven)
Skin tag	6 (two.6)

2. Imaging findings

During the above-mentioned period, 261 cases of USG were performed with 230 patients, of whom 28 patients underwent follow-up USG (59 cases) and 1 patient underwent a spine MRI. In the first USG, echogenic FT was institute in 31 cases (13.5%). Prominent FT (thickness of less than 2 mm, echogenic) was found in 26 cases (mean thickness, 1.iv±0.2 mm; range, 1.0–i.9 mm) and five cases had a thickness of more than than ii mm (thick FT) (2.4±0.iv mm; range, 2.0–two.ix mm) (Fig. 2B). Filar cyst was identified in 57 cases and their size was eight.vi±2.8 mm (range, 3.vii–20.0 mm) (Fig. 2C).

The exact CM level could not be confirmed in 6 patients, but their CM levels were considered normal because the CM was visible at the renal hilum level (considered as L1–ii level). When comparing the case of determining the CM level as the renal hilum level and the instance of confirming the CM level, 4.6±ane.0 months vs. 1.6±i.iii months (P<0.001) indicated that it was difficult to accurately ascertain the CM level later on at least 4.6 months. In that location were 27 cases (11.7%) with low-lying spinal cord (Fig. 2nd). There were 26 cases of isolated low CM in which the tip of CM was located in the L2–3 disc infinite or the eye torso of the L3 medullaris. Only i case presented with the CM below the midbody of L3 (Table two).

Table ii

Initial lumbosacral ultrasound findings

Findings	No. (%)	Size or thickness (mm), mean±SD
Echogenic filum terminale
Prominent FT	26 (11.iii)	1.4±0.ii
Thick FT	5 (2.2)	two.4±0.4
Low-lying spinal string
Between the L2–3 disc space and the mid torso of L3 medullaris	26 (11.iii)	-
Beneath the mid body of L3	1 (0.iv)	-
Filar cyst	57 (24.8)	8.half dozen±6.ii

Follow-up USG was performed with 28 patients. Viii of 10 patients who were followed upwardly after the echogenic FT were echogenic in follow-upwardly, and 2 patients had normal findings. In 13 patients followed up with filar cyst, 1 was not visible in follow-up, three patients were in poor window, and nine patients (iii times in two patients, 20 cases in total) showed follow-up. The thickness of the echogenic FT and filar cyst did not change during the follow-up flow.

Ane patient who had a low lying spinal cord (level L3–4) was suspected of string tethering on USG and this patient had a pocket-size subcutaneous cystic lesion nether the coccygeal cartilage without intraspinal extension. The patient was a 4-mean solar day-one-time girl who was delivered by vaginal delivery at a gestational age of 39 weeks two days and at a birth weight of 2.12 kg. She was admitted to neonatal intensive care unit for intrauterine growth retardation, and USG was performed for sacral dimple, which was found incidentally during hospitalization. A sacral dimple was located in the midline, iii mm from the anal verge. As described above, abnormal findings were detected on spinal USG and spine MRI was performed for further evaluation. The patient was referred to a neurosurgeon; additional testing was recommended including contrast enhancement MRI and surgery was considered. However, the caregiver refused farther evaluation and was the patient was discharged on his ain accord.

Discussion

The sacral dimple is one of the nigh mutual skin lesions, but it is a simple skin lesion in nearly cases and does not bear upon neurologic dysfunction. In our study, half of the patients showed normal USG finding without anomaly. The other patients had filar cyst (24.eight %), echogenic FT (13.5%), and low-lying spinal cord (eleven.seven%). Considering that filar cysts are also classified as normal findings in other literature,10) 74.8% of patients had normal USG findings among our patients. Although patients had aberrant findings for USG, concrete examination and observational findings were nonspecific except in i patient.

I of the major reasons for performing USG is early detection of the possibility of tethered string syndrome. A tethered cord syndrome is caused by a stretch-induced dysfunction of the caudal spinal cord and conus, that oft associated with spinal dysraphism.11) In children, tethered cord syndrome typically present with progressive motor and sensory dysfunction, which may include gait abnormalities and urologic symptoms.12) Although at that place are some asymptomatic patients with anatomic cord tethering, the patients with developed symptoms does non naturally improve without surgical untethering.13) And early on intervention later on symptom development is important for recovery of neurological functions.13,xiv,xv) Early diagnosis is also necessary for prevent neurological harm and adequate surgical correction.16)

In a review article, the incidence of abnormalities in spinal USG in children without dimple was four.8%, which was not significantly unlike from 3.8% in children with a dimple.8) This leads to questions about whether ultrasound should exist performed in patients with simple sacral dimples.17,xviii,19,20,21) Although simply one patient among 230 needed a surgical procedure in our study, considering neurologic problems caused by tethered cord and importance of early diagnosis, USG is worthy for the screening of sacral dimples in infants. In one study of comparing USG and MRI, USG is valuable diagnostic tool for congenital anomalies of the lower spine in infants.22) It is meaningful to perform an USG in Korea, because that the cost of medical services is not expensive compared to the United States or Europe, and hospitals are readily accessible.23) Furthermore, Ohashi et al.24) reported a case of mucopolysaccharidosis blazon Iv, which was diagnosed during sacral dimple evaluation at birth. Prompt evaluation could atomic number 82 to the identification of other treatable diseases in patients.

Cord tethering can occur by FT lipoma, which is the nigh common crusade of thick FT. Therefore, detection of abnormal FT thickening is of import.25) In nigh of the literature, a thickness of FT of more than 2 mm was considered thick FT. Shin et al.25) compared lumbosacral USG and MRI findings and suggested 1.ane mm as the optimal cutoff value for filar lipoma screening on USG. We observed prominent FT in cases of echogenic rather than nerve root, and thick FT in cases in which the thickness was more than 2 mm. The incidence was 11.3% and 2.ii%, respectively.

Irani et al.10) reported that the frequency of filar cysts was 11.8 %, and the short-term results were non significantly different from those of the normal controls. Although the origin and beingness of filar cysts is non well studied, neonatal filar cysts found in isolation on lumbar USG tin be considered equally normal variants. In our report, the incidence of filar cysts in patients with a sacral dimple was 24.viii%. Our findings showed higher prevalence than Irani et al.x); their written report included more than 600 patients and infants older than 12 months were included. There were differences in the number and ages of patients, and no specific symptoms were observed in our patients.

Our study only included patients less than half-dozen months quondam to ensure the accuracy of ultrasound images. Withal, there were patients who visited with a sacral dimple fifty-fifty afterward six months of age. Including these patients makes the mean age of the patients who visited the infirmary with a sacral dimple 2.7±iv.six months (range, 0–62.eight months); 89.5% of the patients visited the hospital 6 months after nascence, and 75.ane% of patients visited the infirmary 3 months after birth. Most of the patients had a sacral dimple during the physical examination for neonatal examination, national infant screening, and vaccination. In our study, 129 patients (56.one%) were normal and the other 100 patients had no neurological abnormalities associated with sonographic findings.9,10,26,27) In some cases, the patients did not revisit the dispensary even though follow-upwards tests were planned. This might exist because the parents of the patients idea that their baby had no neurological abnormalities. No significant changes were plant in the 28 children who underwent a follow-up.

The limitations of this written report included that information technology was a retrospective, single-institutional written report. The example could be made that the medical records were bereft because of the recruitment of retrospective subjects. Future prospective studies should identify long-term clinical outcomes. Infants subsequently 3 months had fewer than other age groups, because progressed ossification made ultrasound imaging difficult. Overcoming regional biases requires investigating the clinical manifestations of the sacral dimple in Korea past studying more patients in multiple institutions. In conclusion, most of the patients in this study had a good clinical course; we found 1 case of abnormality that could lead to neurologic abnormalities in this written report. Therefore, USG screening tests might be useful for children with sacral dimples.

Acknowledgments

This work was supported past a research fund from the Chungnam National University (2014-0656-01). This research was supported by Basic Science Research Plan through the National Research Foundation of Korea (NRF), funded past the Ministry building of Scientific discipline, ICT & Future Planning (grant number: 2015R1C1A1A01052351). This work was presented at the Korean Pediatric Lodge Congress in 2016.

Footnotes

Conflicts of interest: No potential conflict of involvement relevant to this article was reported.

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Source: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6021363/

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