Ultrasonic anatomy of the normal neonatal and infant spine: correlation with cryomicrotome sections and CT

Normal anterior-posterior diameters of the spinal cord and spinal canal in healthy term newborns on sonography

BACKGROUND

There are no published normal values for spinal cord and canal diameters in newborns. Spinal cord and spinal canal diameters are assessed subjectively by radiologists without any objective values for the upper limit of normal.

OBJECTIVE

To determine normal values for anteroposterior (AP) diameters of the spinal cord and spinal canal on sonography in healthy term newborns.

MATERIALS AND METHODS

We performed ultrasound of the entire spine on 37 healthy newborns (23 male, 14 female). The AP diameters of the spinal canal and spinal cord were measured at representative levels of the cervical (C4, C5, C6), thoracic (T5, T6, T7, T8) and lumbar spine (lumbar enlargement and above and below the lumbar enlargement level). Statistical analysis was performed to determine the mean and standard deviation of the spinal canal and spinal cord AP diameter at each aforementioned vertebral level, and their correlations with birth weight, length and head circumference.

RESULTS

The mean AP spinal cord diameter was 4.1±0.5 mm at the cervical level, 3.3±0.3 mm at the thoracic level and 4.4±0.6 mm at the lumbar level. The mean AP spinal canal diameter was 7.7±0.7 mm at the cervical level, 6.2±0.8 mm at the thoracic level, and 8.4±0.7 mm at the lumbar level.

CONCLUSION

In this prospective study, we have determined normal values for AP diameters of the spinal cord and spinal canal on sonography in healthy newborns at representative cervical, thoracic and lumbar levels. This data may assist in evaluating the neonatal spine in clinical situations such as suspected spinal cord injury.

Ecografia computerizzata della colonna vertebrale del neonato

L'ecografia computerizzata costituisce attualemente un'utile e relativamente semplice metodica di studio del canale vertebrale e del suo contenuto, nel neonato a termine e pretermine e nel lattante normale. Viene riportata l'esperienza personale in casi normali, impiegando un apparecchio Acuson 128. Vengono discussi i vantaggi ed i limiti di tale metodica nella rappresentazione dell'anatomia del canale spinale, specie a livello lombo-sacrale, e nello screening della patologia disrafica spinale del primo anno di vita.

L'ecotomografia spinale nello studio del midollo ancorato

Scopo del presente lavoro è puntualizzare il ruolo dell'ecografia nello studio del midollo ancorato che rappresenta un'aspetto comune a molta della patologia spinale infantile e può prestarsi ad un'analisi globale dello stato dell'arte dello studio ecografico del midollo spinale, alla luce dell'esperienza acquisita negli anni e del continuo progresso tecnologico.

Dopo qualche cenno storico e alcune puntualizzazioni di carattere tecnico e di anatomia ecografica e stabilita la principale indicazione all'ecografia spinale nel neonato-lattante consistente nella ricerca delle spine bifide occulte, sospettate nel caso di masse posteriori ricoperte dalla cute o di fossette/seni dorsali, spesso associate a midollo ancorato, abbiamo illustrato i segni generici ecografici di midollo ancorato ed i differenti rilievi e potenzialità della metodica nel bilancio delle varie masse caudali responsabili dell'ancoraggio del midollo. L'eco non presenta alcun interesse nello studio diagnostico dei disrafismi spinali aperti mentre potrebbe rivelarsi utile nella ricerca postoperatoria di un eventuale riancoraggio midollare, valutato in base all'assenza della fisiologica pulsatilità del midollo. A tal proposito abbiamo recentemente effettuato una comparazione tra presenza o meno di motilità spinale valutata ecograficamente e presenza di segni clinici in pazienti precedentemente operati per disrafismo spinale.

In conclusione, lo studio ecografico del midollo spinale del neonato-lattante, pur presentando grossi limiti, trova giustificazione nella innocuità, nella facilità d'uso e nella possibilità di ottenere immagini in tempo reale. La presenza o il solo sospetto clinico di patologia disrafica impongono comunque sempre il completamento del bilancio diagnostico mediante RM/TC.

Defining the line between hydromyelia and syringomyelia. A differentiation is possible based on electrophysiological and magnetic resonance imaging studies

PURPOSE

With the frequent use of magnetic resonance imaging (MRI), patients with subtle and diffuse symptoms due to small syrinx cavities increasingly present to neurosurgical care. In this respect, a dilated central canal, hydromyelia, must be separated from patients with true syringomyelia with an underlying disorder, as they do not share clinical and radiological features. We hypothesize that a differentiation of these two entities with distinct diagnostic tools is possible.

METHODS

To describe the entity of hydromyelia, we excluded all patients from the syringomyelia database (n = 142) with any obvious cause of a syringomyelia, any objective neurological deficits on clinical examination, pathological results on electrophysiological monitoring (SSEP, MEP, silent periods) or a widening of the spinal cord cavity of more than 6 mm on MRI [routine acquisitions with FLAIR, T1/T2-weighted images, Cine and CISS (constructive interference in steady-state) studies]. Life quality was assessed through SF-36 questionnaires and an individualized questionnaire for the clinical history, pain and alternative therapies.

RESULTS

Forty patients (15 males/25 females) matched the criteria of a hydromyelia. With a mean age of 36.7 years (range 11-62), they almost all presented with pain (79%) or dysaesthesia of the limbs, with some having been an incidental finding (10%). Over a follow-up time of 36.9 months (range 6-93) there was no neurological or radiological deterioration.

CONCLUSIONS

Patients with a hydromyelia do not share clinical or radiological characteristics with patients harbouring a true syringomyelia. As hydromyelia does not represent a disease with an underlying pathology, no clinical or radiological progression has been seen. With sophisticated diagnostic tools to rule out any pathology this subset of patients can be identified.

Evaluation of spinal ultrasound in spinal dysraphism

AIMS

The aims of this study were to evaluate the role of spinal ultrasound in detecting occult spinal dysraphism (OSD) in neonates and infants, and to determine the degree of agreement between ultrasound and magnetic resonance imaging (MRI) findings.

MATERIALS AND METHODS

Eighty-five consecutive infants had spinal ultrasound over 31 months. Of these, 15 patients (age 1 day-7 months, mean 40 days; nine male) had follow-up MRI. Ultrasound and MRI findings were correlated retrospectively.

RESULTS

Six out of 15 (40%) ultrasound examinations showed full agreement with MRI, seven of 15 (47%) had partial agreement, and two of 15 (13%) had no agreement. In the present series ultrasound failed to visualize: four of four dorsal dermal sinuses, three of four fatty filum terminales, one of one terminal lipoma, two of four partial sacral agenesis, three of four hydromyelia and one of 10 low-lying cords.

CONCLUSION

Agreement between ultrasound and MRI was good, particularly for the detection of low-lying cord (90%). Therefore we recommend ultrasound as a first-line screening test for OSD. If ultrasound is abnormal, equivocal or technically limited, MRI is advised for full assessment.

US of the spinal cord in newborns: spectrum of normal findings, variants, congenital anomalies, and acquired diseases

Ultrasonography (US) of the spinal cord is performed in newborns with signs of spinal disease (cutaneous lesions of the back, deformities of the spinal column, neurologic disturbances, suspected spinal cord injury due to traumatic birth, and syndromes with associated spinal cord compression). The examination is performed with high-frequency linear- and curved-array transducers in the sagittal and axial planes from the craniocervical junction to the sacrum. Normal variants such as transient dilatation of the central canal and ventriculus terminalis can be demonstrated with US. US allows detection of congenital malformations, such as myelocele or myelomeningocele, spinal lipoma, dorsal dermal sinus, tight filum terminale syndrome, diastematomyelia, terminal myelocystocele, lateral meningocele, caudal regression syndrome, and hydromyelia or syringomyelia. Acquired intraspinal diseases following birth trauma and transient alterations after lumbar puncture can also be detected with US. US can demonstrate the entire spectrum of intraspinal anatomy and pathologic conditions with high geometric resolution. Therefore, US should be considered the initial imaging modality of choice for investigating the spinal cord in newborns.

Level of conus medullaris in term and preterm neonates

AIMS

To compare the levels of conus medullaris in preterm and term neonates; to show the time of ascent to normal; and to evaluate the babies with low conus medullaris levels for tethered cord syndrome.

METHODS

Levels were assessed using ultrasonography in 41 preterm and 64 term neonates.

RESULTS

In the preterm group the conus medullaris level in one infant (2.4%) was below L4. In three infants (7.2%) it was between L2 and L3 and in 37 infants (90.4%) it was above L2. In the term group it was below L4 in one baby (1.6%), between L2 and L3 in four (6.3%), and above L2 in 57 babies (92.1%). The difference in the conus medullaris levels between term and preterm neonates and genders was not significant. Two patients, one with a conus medullaris level at L4-L5, and the other at L2-L3, had Down's syndrome.

CONCLUSION

The ascent of conus medullaris seems to occur early in life. It is important to follow up patients with conus medullaris levels at or below the 4th lumbar vertebra for the development of tethered cord syndrome.

Assessment of maternal anxiety following neonatal screening and investigation for occult spinal dysraphism

The objective was to determine maternal anxiety and attitudes associated with a programme of neonatal screening and investigation for occult spinal dysraphism. Questionnaires were completed after diagnostic investigation (time 1) and 6 months later (time 2) by 83 mothers of babies with possible markers of occult spinal dysraphism who were normal on spinal ultrasound. Outcome measures were: attitudes to the programme; maternal adjustment and attitudes to the baby; the State-Trait Anxiety Inventory. Fifty-four other postnatal mothers formed the comparison group for maternal adjustment. No significant differences were found between investigation group (time 1) and comparisons on measures of maternal adjustment. Anxious mothers gave more negative responses to some maternal adjustment items but not to attitudes to the programme. Mean state anxiety at time 1 (33.66) and time 2 (33.69) and mean trait anxiety (36.23) were not higher than in mothers of normal babies. It can be concluded that a programme of investigation for neonatal abnormalities that pays attention to detail need not cause excessive maternal anxiety. However, some mothers remain anxious even after receiving normal results. Anxiety can be assessed during appraisal of a new investigation programme, but refinements are needed.

Atypical and equivocal sonographic features of the spinal cord in neonates

Thanks to the wider use of sonography to examine the spinal content in the neonate, normal anatomy and anomalies may be detected easily. Yet, unusual sonographic patterns are also observed. These must be differentiated from true pathologies. During a prospective study of 103 neurologically asymptomatic neonates, atypical sonographic patterns were found in 16 patients, corresponding to normal variants in 13. Nine of these 13 patients presented with a widening of the distal part of the central echo complex (one had a dilated ventriculus terminalis). Nerve roots of the cauda equina were disposed asymmetrically in three patients; the spinal cord movements were still present. In two of these babies, this distribution was associated with thin arachnoid pseudocysts. One patient presented with transitorily hyperechoic and narrow subdural spaces, probably related to neonatal dehydration. None of the 13 patients showing normal variants required any treatment. The other 3 patients (of 16) presented with equivocal entities of unknown evolution: sonographic tethered cord, fibrolipoma of the filum terminale and epidural varices. Sonography is highly accurate in evaluating the spinal cord content and aids differentiation of normal and normal variants from equivocal or pathological entities.

Sonographic Evaluation of the Spine in Infants and Neonates

Ultrasound is a rapid, noninvasive, cost-effective method of evaluating the spine in infants younger than six months of age. This report reviews sonographic scan procedure and normal sonographic spinal anatomy, and illustrates the sonographic appearance of occult spinal anomalies, such as meningocele, meningomyelocele, tethered cord, diastematomyelia, and sacrococcygeal teratoma.

Imaging of the pediatric spine and its contents

We are at the crossroads of imaging of the diseases of the spine and its contents. There are different competing imaging modalities, each with its own merits and demerits. This review paper is designed to identify the strengths and weaknesses of the various available imaging modalities and to recommend one or a combination of imaging modalities that are suited for assessing a particular disease process. At present, magnetic resonance imaging has proved its extreme usefulness in depicting diseases of the spinal cord and its coverings. As more innovations and sophistications occur in magnetic resonance imaging, it is hoped that it will play a pivotal role in the investigation of abnormalities of the spinal cord and perhaps even of the spine itself.