SPINE

1. SPINE CONGENITAL

2. Arnold-Chiari Malformation • Syringomyelia/Hydromyelia • Tethered Cord CONGENITAL

3. ARNOLD-CHIARI MALFORMATION

4. Arnold-Chiari malformations consist of a spectrum of congenital anomalies that affect the hindbrain. They are characterized by a downward elongation of the brainstem (medulla oblangata), cerebellum (cerebellar tonsils), and the fourth ventricle into the cervical portion of the spinal cord. Arnold-Chiari malformations are categorized into three types. Description:

5. In an Arnold-Chiari Type I, the cerebellar tonsils along are displaced 5 to 6 mm or more below the foramen magnum. There is no hydrocephalus involved and the fourth ventricle remains in its normal location. A syringohydromyelia (syrinx) of the cervical spinal cord may be seen. This may be associated with Klippel-Feil syndrome.

6. In an Arnold-Chiari Type II, the cerebellar tonsils and vermis of the fourth ventricle, cerebellum, and medulla oblangata have herniated down through the foramen magnum into the cervical spinal canal. Obstruction of the fourth ventricle results in hydrocephalus. This type is associated with myelomeningocele and agenesis of the corpus callosum.

7. In an Arnold-Chiari Type III malformation is characterized by displacement of the cerebellum meninges, and sometimes the brainstem into an encephalocele. Encephaloceles result from a herniation of the brain or meninges, or both, through a skull defect. Characteristics seen in Type II Chiari malformations may be present. It occurs in approximately 1 in 4000 to 5000 deliveries..

8. Type I Arnold-Chiari malformations are found more often in adults (incidentally by MRI) than in children. There does not seem to be any gender preference. Etiology:

9. The prevalence for AD is less than 1% before the age of 65; however, this quickly increases to 10% of the population over the age of 65 and between 30% to 50% over the age of 85 years and older. There seems to be a higher prevalence in women than in men. Epidemiology :

10. Hydrocephalus and developmental defects may be seen early on in infants. Young adults may be asymptomatic until neurologic deficits such as craniocervical junction abnormalities (eg, progressive ataxia) occur. Signs and Symptoms :

11. Imaging Characteristics: • MRI is the modality of choice for diagnosing this disorder. CT • The effectiveness of demonstrating the anomaly with CT is limited due to the bony surroundings and axial imaging.

12. MRI • T1- and T2-weighted pulse sequences will demonstrate the downward herniation of the cerebellar tonsils through the foramen magnum into the upper cervical canal. • Associated findings may include syringomyelia and hydrocephalus.

13. Surgery intervention may be used to decompress the posterior fossa. Shunt placement is used to treat hydrocephalus. Treatment:

14. Depends on the type, age of the patient when diagnosed, and extent of other related developmental defects. The prognosis for infants may be worse than for adults. Prognosis:

15. Figure 1. Arnold-Chiari Malformation T1-weighted sagittal image demonstrates downward herniation of the cerebellar tonsils (arrow) through the foramen magnum into the upper cervical spinal canal with compression of the medulla oblangata.

16. SYRINGOMYELIA / HYDROMYELIA

17. Syringomyelia refers to any fluid-filled cavity within the spinal cord. A cavity in the cord may be due to central canal dilatation (hydromyelia) or a cavity eccentric to the central canal (syrinx). It is difficult to differentiate between these two entities. Description:

18. Approximately 50% of syringomyelia are congenital (Chiari malformation). Acquired cases are the result of intramedullary tumors, trauma, infarctions, and hemorrhage. In some cases there is no known cause. Etiology:

19. Approximately 90% occur in associated with an Arnold-Chiari Type I malformation, but also may include, myelomeningocele, basilar skull impression (platybasia), atresia of the foramen of Magendie, or Dandy-Walker cysts. Epidemiology :

20. Depends on the extent of the syrinx. The patient may experience sensory loss (loss of pain and temperature), muscle atrophy (lower neck, shoulders, arms, and hands), and thoracic scoliosis. Signs and Symptoms :

21. Imaging Characteristics: • MRI is the modality of choice for diagnosing of syringomyelia. CT • Postmyelogram CT demonstrates a contrast filled syrinx surrounded by the hypodense spinal cord.

22. MRI • Signal intensity of a syrinx may be isointense to CSF on T1-weighted images. • Signal intensity of a syrinx would be isointense to CSF on T2-weighted images.

23. Surgical drainage of the syrinx is the suggestive treatment. Treatment:

24. Variable, depending on the extent of the syrinx. Prognosis:

25. A B Figure 1. Syringomyelia Sagittal T1W (A) shows abnormal low intramedullary signal and cord expansion. The abnormal fluid within the spinal cord is hyperintense on the sagittal T2W image (B).

26. Figure 2. Syringomyelia Axial T2W of the cervical spine shows hyperintense fluid in the spinal cord (arrow) consistent with a syrinx.

27. TETHERED CORD

28. A tethered cord is a condition in which the conusmedullaris is prevented from ascending to its usual position at the level of L1-L2. It is tethered at an abnormally low position by a tight, short, thickened filumterminale, fibrous bands, intradurallipoma, or some other intraduralabdnormality. Description:

29. This congenital abnormality is seen in neonates. Etiology and Epidemiology:

30. Patient presents with muscle weakness, abnormal lower limb reflexes, bowel and bladder dysfunction, back pain, and scoliosis. Signs and Symptoms :

31. Imaging Characteristics: • MRI is the modality of choice for diagnosis of a tethered cord. MRI • Tip of the conusmedullaris is below the level of L2. • T1-weighted axial shows a thickened (>2 mm in diameter). • The conusmedullaris may be tethered by a spina bifida occulta and/or intradurallipoma (posteriorly displaced by fat), glial cells, and collagen.

32. Surgery in infancy or early childhood is required to prevent progressive neurologic deficit. Treatment:

33. Depends on the extent of the tethered cord and the age of the young child at the time of diagnosis and treatment. Prognosis:

34. Figure 1. Tethered Cord Axial contrasted CT scan through pelvis shows abnormal fat density within the sacral spinal canal consistent with terminal lipoma.

35. A B Sagittal T2W (A) and coronal oblique T1W (B) images through lumbar spine demonstrates thickened terminal filum and a terminal lipoma. Note: extension of fat through spinal dysraphism into spinal canal. Figure 2. Tethered Cord

36. SPINE DEGENERATIVE

37. Herniated Disk • Spinal Stenosis • Spondylolisthesis DEGENERATIVE

38. HERNIATED DISK

39. A herniated disk is also referred to as a ruptured or protuded disk. A herniated disk occurs when part or the entire nucleus pulposus (the soft, gelatinous, central portion of an intervertebral disk) is forced through the disk’s weakened or torn outer ring (annulus fibrosus). This extruded herniated disk may impinge upon spinal nerve roots as they exit from the spinal canal or on the spinal cord itself. Description:

40. Herniated disks may result from severe trauma or strain, or may be related to intervertebral joint degeneration. In older patients with degenerative disk disease, minor trauma may cause herniation. Etiology:

41. About 90% of herniated disks occur in the lumbosacral spine, with the majority of these occuring at L5-S1, and rest at either L4-L5 or L3-L4. A small percent of herniated disks involve the cervical spine, with the majority of these being at C5-C6 and C6-C7. Only 1% to 2% of herniated disks occur in the thoracic spine. Epidemiology :

42. Patients with lumbosacral herniated disks will present with low back pain, radiating to the buttocks, legs and feed, usually unilaterally. Sensory and motor loss, muscle weakness, and atrophy of the leg muscles may be experienced if a lumbar spinal nerve root is compressed. Cervical disk herniations present with pain in the neck and upper extremeties and weakness, and neurologic deficits, such as muscle spasms, numbness, and tingling are common symptoms. Signs and Symptoms :

43. Imaging Characteristics: • As a result of excellent soft tissue resolution and multiplanar imaging, MRI is the imaging modality of choice for diagnosing herniated disk.

44. MRI and CT • Demonstrate disc degeneration. • Herniated disc usually laterized to one side compressing the thecal sac and nerve root. • Free disc fragments may migrate superiorly or inferiorly.

45. Conservative treatment consists of bed rest, heat, exercise, and medication ranging from anti-inflammatory drugs to muscle relaxants. Patients not responding to conservative treatment may require surgical intervention. Treatment:

46. Prognosis is very mixed, dependent on the severity of damage, the quality and skill of surgical intervention, the age, size, and weight of the patient, and whether there is a physically active or sedentary lifestyle. Prognosis:

47. T1-weighted sagittal MR image shows herniated disc at the L5-S1 level. Figure 1. Herniated Disk

48. Figure 2. Herniated Disc T1-weighted axial MR image demonstrates right-sided herniated disk at the L5-S1 level compressing the right side of the thecal sac and nerve root.

49. T2W sagittal MR of L5-S1 verify disc bulge. End-plate hyperintensity about this disc space was degenerative Figure 3. Herniated Disk

50. SPINAL STENOSIS