Neonatal Spine Tanya Nolan

Embryology Ectoderm Mesoderm Neural tube arises from ectodermal cells and becomes the spinal cord and brain. Mesoderm Forms bony spine, meninges, and muscle

Embryology Defects of the spine occur in the first 8.5 wks of life as the fetal nervous system develops Incomplete seperation of the neural tube from the ectoderm Cord tethering, Diastematomyelia, or a Dermal sinus Premature Seperation Lipomas Failure of neural tube to fold and fuse in the midline Myelomeningocele Disorders of distal cord Fibrolipomas of the filum terminale

Anatomy Vertebral Column Houses spinal cord, spinal nerve roots, and meninges Total 33 Vertebrae 7 Cervical 12 Thoracic 5 Lumbar 5 Sacral 4 Coccygeal

Spinal Cord Cylindrical, grayish white structure Meninges Dura Mater Outer strong, dense, fibrous sheet Arachnoid Mater Middle layer Subarachnoid Space: Filled with cerebral spinal fluid. Pia Mater Inner vascular layer

Spinal Cord Begins Terminates Above the formamen magnum and is continuous with the medulla oblongata Terminates Adult: Lower border of L1 Child: Upper border of L3

Spinal Cord Conis Medularis Filum Terminale Cauda Equina Inferiorly cord tapers to a point Filum Terminale Prolongation of pia matter that is attached to the coccyx Cauda Equina “Horse tail” Lower nerve roots

Nerve Roots 31 Pair Carries impuses to and from the brain to the rest of the body.

Indications for Sonographic Examination Midline Cutaneous Abnormality Sacral Dimple Deep Asymmetric Suspicious if more than 1 inch from anus Hemangioma Raised midline Hairy Patch Tail-like projection of lower spine Diagnosis of myelomeningocele or myeloschisis Lower extremity deformity

Sonographic Technique Patient Position Prone Spine flexed (seperates posterior elements) Lateral Decubitus Upright Transducer High frequency linear array Possible stand off pad

Sonographic Technique Where do you begin? 1) Sacral area & count stepwise ascent of sacral vertebral elements 2) Count from lowest rib bearing vertebra (rib over kidney & follow medially) Determine level of Conus Medullaris!!!

Sonographic Appearance Vertebral Bodies Echogenic; anterior Lamina Slighly off midline; “Overlapping Roof Tiles” Spinous Processes Inverted “U”s Coccyx Hypoechoic, do not mistake for a fluid collection. Spinal Cord Hypoechoic with slightly echogenic borders and an echogenic line extending along its middle. Nerve Roots Echogenic Move and change configuration during respiratory variations. Conus Medullaris Normally above endplate of L3; Most cords end above L2. (Most tethered cords are unquestionably low.)

Sonographic Appearance Sagittal View Anterior echogenic body surface; posterior dorsal spinal elements. 1. Posterior elements or spinous processes 2. posterior arachnoid-dural layer bordering spinal canal 3. subarachnoid space filled with cerebrospinal fluid 4 posterior margin of the spinal cord 5. spinal cord with central echo complex 6. Anterior margin of the spinal cord

Sonographic Appearance Level of the Conus – Sagittal View Tapered conus medullaris shows the end of the spinal cord. 1. Posterior elements or spinous processes 2. cauda medullaris 3. filum terminale 4. cauda equina and nerve roots.

Sonographic Appearance Level of the Conus – Transverse View Nerve roots are echogenic as they surround the spinal cord. 1. Paravertebral muscles 2. Laminae of vertebral arches 3. subarachnoid space filled with cerebrospinal fluid 4. spinal cord with central echo complex 5. paired dorsal and ventral nerve roots 6. vertebral body.

Pathology

Tethered Cord Fixation of cord @ caudal location (below L3) Diminished cord movement. Cord mechanical stretching, distortion, and ischemia with growth and activity. TC L

Tethered Cord Sonographic Findings Visualization of cord caudal to normal termination Diminished cord pulsation Eccentric cord location with the canal Intradural lipoma and tethered cord in 2-week-old girl with hairy patch on lower back. Longitudinal sonogram reveals typical features of hyperechoic lipoma (calipers) attached to dorsal aspect of thoracolumbar spinal cord. Conus is tethered to mass at L3-L4 disk space.

Lipoma Mass of filum terminale Continuous with subcutaneous tissues & presents as a fatty back lump. Frequently associated with tethered cord. Sonographic Finding Echogenic Mass

Hydromelia Dilation of central canal Diffuse or focal Associated with myelomeningocele and diastemotomyelia May mimic or co-exist with syringomyelia Sonographic Findings Separation of echogenic linear structures of central canal. Hydromyelia in a 1-month-old infant in whom lumbar myelomeningocele and thoracic hydromyelia were noted on the 1st day of life. Sagittal US scan shows a dilated central canal (arrows).

Diastamatomyelia Cord is split at one or more sites by a septum Assoiated with meningocele or myelomeningocele Vertebral column abnormal on plain radiography Sonographic Findings Split segments best seen in transverse views Transverse scan of the lumbar spinal canal shows left and right hemicords. Each hemicord has an eccentric central canal

Cysts on Spinal Cord May be seen in cauda equine or filum terminale Small cysts in filum terminale may be remnants of a terminal ventricle or an arachnoid pseudocyst Related to Tethered Cord

Myelomeningocele Spina Bifida Low termination of spinal cord Protruding pouch containing CSF and nerves Sonographic Findings Pre-op exams can differentiate between myelomeningocele and meningocele Flat nontubulated cord with nerve roots extending into the defect.

Dermal Sinus Tract Small dimple-like opening in the midline of the spine connecting deep into the spinal cord. The majority located at the level of the sacrum or the lumbar region. Communication with spinal canal contents increases possibility of meningitis Attaches to the end of the spinal cord, causing tethering. Sonographic Findings Easily followed if fluid filled or disrupts normal soft tissue planes Dural penetration is difficut to ascertain or exclude on sonography