2 Embryology Ectoderm Mesoderm Neural tube arises from ectodermal cells and becomes the spinal cord and brain.MesodermForms bony spine, meninges, and muscle
3 EmbryologyDefects of the spine occur in the first 8.5 wks of life as the fetal nervous system developsIncomplete seperation of the neural tube from the ectodermCord tethering, Diastematomyelia, or a Dermal sinusPremature SeperationLipomasFailure of neural tube to fold and fuse in the midlineMyelomeningoceleDisorders of distal cordFibrolipomas of the filum terminale
5 Spinal Cord Cylindrical, grayish white structure Meninges Dura Mater Outer strong, dense, fibrous sheetArachnoid MaterMiddle layerSubarachnoid Space: Filled with cerebral spinal fluid.Pia MaterInner vascular layer
6 Spinal Cord Begins Terminates Above the formamen magnum and is continuous with the medulla oblongataTerminatesAdult: Lower border of L1Child: Upper border of L3
7 Spinal Cord Conis Medularis Filum Terminale Cauda Equina Inferiorly cord tapers to a pointFilum TerminaleProlongation of pia matter that is attached to the coccyxCauda Equina“Horse tail”Lower nerve roots
8 Nerve Roots31 PairCarries impuses to and from the brain to the rest of the body.
9 Indications for Sonographic Examination Midline Cutaneous AbnormalitySacral DimpleDeepAsymmetricSuspicious if more than 1 inch from anusHemangiomaRaised midlineHairy PatchTail-like projection of lower spineDiagnosis of myelomeningocele or myeloschisisLower extremity deformity
10 Sonographic Technique Patient PositionProneSpine flexed (seperates posterior elements)Lateral DecubitusUprightTransducerHigh frequency linear arrayPossible stand off pad
11 Sonographic Technique Where do you begin?1) Sacral area & count stepwise ascent of sacral vertebral elements2) Count from lowest rib bearing vertebra (rib over kidney & follow medially)Determine level of Conus Medullaris!!!
12 Sonographic Appearance Vertebral BodiesEchogenic; anteriorLaminaSlighly off midline; “Overlapping Roof Tiles”Spinous ProcessesInverted “U”sCoccyxHypoechoic, do not mistake for a fluid collection.Spinal CordHypoechoic with slightly echogenic borders and an echogenic line extending along its middle.Nerve RootsEchogenicMove and change configuration during respiratory variations.Conus MedullarisNormally above endplate of L3; Most cords end above L2. (Most tethered cords are unquestionably low.)
13 Sonographic Appearance Sagittal View Anterior echogenic body surface; posterior dorsal spinal elements.1. Posterior elements or spinous processes2. posterior arachnoid-dural layer bordering spinal canal3. subarachnoid space filled with cerebrospinal fluid4 posterior margin of the spinal cord5. spinal cord with central echo complex6. Anterior margin of the spinal cord
14 Sonographic Appearance Level of the Conus – Sagittal View Tapered conus medullaris shows the end of the spinal cord.1. Posterior elements or spinous processes2. cauda medullaris3. filum terminale4. cauda equina and nerve roots.
15 Sonographic Appearance Level of the Conus – Transverse View Nerve roots are echogenic as they surround the spinal cord.1. Paravertebral muscles2. Laminae of vertebral arches3. subarachnoid space filled with cerebrospinal fluid4. spinal cord with central echo complex5. paired dorsal and ventral nerve roots6. vertebral body.
17 Tethered Cord Fixation of cord @ caudal location (below L3) Diminished cord movement.Cord mechanical stretching, distortion, and ischemia with growth and activity.TCL
18 Tethered Cord Sonographic Findings Visualization of cord caudal to normal terminationDiminished cord pulsationEccentric cord location with the canalIntradural 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.
19 Lipoma Mass of filum terminale Continuous with subcutaneous tissues & presents as a fatty back lump.Frequently associated with tethered cord.Sonographic FindingEchogenic Mass
20 Hydromelia Dilation of central canal Diffuse or focalAssociated with myelomeningocele and diastemotomyeliaMay mimic or co-exist with syringomyeliaSonographic FindingsSeparation 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).
21 Diastamatomyelia Cord is split at one or more sites by a septum Assoiated with meningocele or myelomeningoceleVertebral column abnormal on plain radiographySonographic FindingsSplit segments best seen in transverse viewsTransverse scan of the lumbar spinal canal shows left and right hemicords. Each hemicord has an eccentric central canal
22 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 pseudocystRelated to Tethered Cord
23 Myelomeningocele Spina Bifida Low termination of spinal cordProtruding pouch containing CSF and nervesSonographic FindingsPre-op exams can differentiate between myelomeningocele and meningoceleFlat nontubulated cord with nerve roots extending into the defect.
24 Dermal Sinus TractSmall 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 meningitisAttaches to the end of the spinal cord, causing tethering.Sonographic FindingsEasily followed if fluid filled or disrupts normal soft tissue planesDural penetration is difficut to ascertain or exclude on sonography