Spinal ultrasound is becoming remarkably accepted as a first-line screening imaging modality used in neonates suspected of spinal dysraphism [12]. Motion artifacts, which can considerably reduce the quality of MRI in young children, play a minor role during the real-time ultrasound. The diagnostic value of spinal ultrasonography is nearly similar to MRI for diagnosis of main spinal anomalies in infants [13, 14].
According to the demographic profile; the age of our study group ranged from 2 months to 12 years and a mean age of 15.6 ± 13 months. The patient group of ≤ 2 years old involved 30 patients, while the patient group of > 2 years old involved 15 patients. Study population represented 26 females (57.8%) and 19 males (42.2%).
In other study by Kumari et al. which examined 66 patients (age ranged from 17 days to 13 years). Most of the children were ≤ 2 years old. Fourty (66.6%) patients were females and 26 (33.3%) were males. They found that swelling in the back was also the commonest clinical feature (77.2%) [15].
Mehta et al. studied 50 patients and found that the most common anomalies were type II Arnold-Chiari malformation with lumbar meningomyelocele (34%), spina bifida occulta (22%), and diastmatomyelia (18%) [16].
In another study by Dhingani et al., where age group of the studied patients ranged from 2 days to 16 years. 84.21% patients were < 10 years old, and the neonatal period was the most common presenting age group accounting for 39.47% of total cases. The most common clinical finding at presentation was also midline back swelling (60.53%); however, the next common finding was urinary incontinence (47.37%), followed by skin dimple in back (28.95%), fecal incontinence (21.05%), hair tuft (3.33%), and dermal sinus (3.33%) [17].
In our study, lumbosacral spine was the most common region involved in 32 patients (71.1%).
We shared comparable results with Dhingani et al. who found that the lumbosacral spine was the most commonly involved spinal segment found in 52.63% of patients, followed by sacrococcygeal region (34.21%) [17].
Our study results as regards spinal ultrasound are comparable with study by Dhingani et al. which showed that the most common anomaly was tethered cord seen in 23 (79.31%) patients, syrinx (62.06%), MMC (48.27%), and lipomyelomeningeocele (27.58%) [17]. And another study by Taahira Nishtar et al., which revealed that 2 of the studied 53 patients (4%) has diastematomyelia [18].
Dhingani et al. displayed that open SD was found in 14 (36.84%) patients and closed SD was seen in 24 (63.16%) patients. It was found that 26.32% of patients with closed SD had subcutaneous mass, and 14 patients (36.84%) were not having subcutaneous mass. In open SD, myelomeningocele was the most common anomaly accounting for 14 (36.84%) cases [17].
Both spinal USG and MRI were performed in whole 45 cases. Agreement between findings of these two modalities was studied. There were 10 cases aged > 2 years revealed no agreement between MRI and USG findings that there was acoustic shadowing from posterior spinal elements ossification, so ultrasound was unreliable and we could not reach the primary diagnosis by this modality (Fig. 5). Thus, statistics was divided to age groups ≤ 2 years old (before complete ossification of spinal elements) and > 2 years old (after ossification of spinal elements) in order to reach significant results.
We agreed with Dhingani et al.’s study which showed that 23 out of 29 patients (79.31%) showed full agreement between spinal USG and MRI examinations, and 6 out of 29 patients (20.69%) showed partial agreement. In these six cases with partial agreement; spinal USG missed tethered cord and syrinx in three cases, small lipomatous component in one case of lipomyelomeningeocele, one case of intradural lipoma, and one case of split cord associated with myelomeningocele [17].
In another study by Hughes et al., ultrasound showed full agreement with MRI in 6 of 15 patients (40%), partial agreement in 7 of 15 patients (47%) and no agreement in 2 of 15 patients. Ultrasound missed some findings in some cases as dorsal dermal sinuses, fatty filums, terminal lipoma, partial sacral agenesis, hydromyelia and low-lying cords. However, overall, in 12 of 13 (92%) cases with abnormal MRI, ultrasound identified at least one of the concurrent abnormalities. No agreement was found between ultrasound and MRI in two cases, one being false-positive and the other false-negative. This resulted in an overall false-negative diagnosis in one of 12 patients (8%) with abnormal MRI, and an overall false-positive diagnosis in one of 3 patients with a normal MRI [19].
Dhingani et al., showed that the primary anomaly was identified and diagnosed on USG in 23 of 25 (92%) cases, while the primary anomaly was diagnosed in 25 cases by MRI (4 cases were having isolated vertebral anomalies or sacrococcygeal agenesis). USG is not an ideal modality for identifying other abnormalities associated with spinal dysraphism such as tethered cord, syrinx, and split cord, as compared to MRI [17].
Spinal USG has less sensitivity compared to MRI in detecting closed type of spinal anomalies or other findings associated with the primary anomaly, various vertebral anomalies and kyphoscoliotic deformity. MRI is also superior in identifying the exact extent of detected anomaly such as intraspinal extension of lipomatous tissue; the level, extent and type of split cord; extent of vertebral agenesis; and shape and level of conus termination in the case of caudal regression syndrome (CRS). Thus, MRI identifies all concurrent abnormalities, gives a complete diagnosis, and helps in planning better management.
This study had also some limitations: (1) Spinal ultrasonography is not beneficial after the age of 2 years; (2) most cases of closed spinal dysraphism are not complaining at all or presented to neurosurgery and neurology clinics when they are older either presented by congenital scoliosis or urinary incontinence (after the age of 5 years), so these cases are underdiagnosed by ultrasound, and MRI is the only best modality for their diagnosis. Studies with larger samples are needed to provide more realistic representative results than smaller ones to increase external validity.