Neuroradiology Teaching

  Correct Answer! The image above shows loss of gray-white differentiation (cytotoxic edema) in the right operculum, insula, external/extreme capsule, and lentiform nucleus. Additionally, the right sylvian fissure is asymmetrically effaced. The findings are consistent with an acute infarct with the expected right MCA distribution.

  Correct Answer! The image above shows an extra-axial hemorrhage associated with an acute fracture. This association along with the lentiform shape of the hemorrhage support an epidural over subdural or subarachnoid hemorrhage. In contrast to the lentiform shape of epidural hemorrhage, subdural hematoma generally have a crescentic shape. While subdural hematoma do not cross the midline or tentorium, epidural hemorrhage do not cross suture line. Subdural hematomas are typically caused by injured bridging veins. Epidural hematoma are generally caused by arterial injury. Subarachnoid hemorrhage typically layers within sulci or the basal cisterns. It can be caused by trauma or rupture of an aneurysm.

  Correct Answer! Involvement of the petrous segment of the carotid canal is associated with a relatively high incidence of acute injury to the internal carotid artery (dissection, occlusion and pseudoaneurysm formation). Also, Venous sinus injuries are common with occipital skull fractures. However, mainly occipital condylar and cervical fractures are associated with injury to the vertebral arteries.

  Correct Answer! The fracture extends through the base of the odontoid process below the level of the transverse band of the cruciform ligament. Hangman's Fracture is a bilateral fracture of pars interarticularis.

• Type I
  • Rare
  • Fracture of the upper part of the odontoid peg
  • Above the level of the transverse band of the cruciform ligament
  • Usually considered stable
• Type II
  • Most common
  • Fracture at the base of the odontoid
  • Below the level of the transverse band of the cruciform ligament
  • Unstable
  • High risk of non-union
• Type III
  • Through the odontoid and into the lateral masses of C2
  • Relatively stable if not excessively displaced
  • Best prognosis for healing because of the larger surface area of the fracture

  Correct Answer! 

• A: A "Gibbus" deformity is commonly seen with tuberculosis, which is focal kyphosis.
• B: TB is one of the few organisms that does not tend to involve the intervertebral disc space for diskitis osteomyelitis in its early stages.
• C: Diskitis osteomyelitis with bilateral psoas abscesses should raise suspicion for tuberculosis.
• D: TB tends to involve multiple vertebral levels, rather than a single level.
• E: Calcifications within the abscesses of the iliopsoas are more commonly seen with granulomatous inflammation as is seen with tuberculosis.

  Correct Answer! 

• A: Edema and enhancement within the involved infected vertebra is frequently seen.
  B: Air within the intervertebral disc space is almost NEVER seen with diskitis osteomyelitis (emphasis on *almost*). If you have an MRI suspicious for osteomyelitis and you order a CT at the same time that demonstrates air, decrease your suspicion of osteomyelitis.
  C: Non-tuberculous diskitis osteomyelitis often presents with early endplate irregularity/destructive changes.
  D & E: There is frequently paraspinal/epidural soft tissue infection associated with discitis osteomyelitis.
   

  Correct Answer! 

• A: Histoplasmosis is more frequently seen in the patients exposed in the Ohio and Mississippi valleys. Most common sequela is calcified granulomas, less commonly pulmonary nodules. Chronic infection can mimic TB with upper lobe pulmonary fibrocavitary consolidation. Rarely, patients can have fibrosing mediastinitis -> pulmonary venous obstruction -> bronchial stenosis -> pulmonary artery stenosis. Affected lymph nodes tend to calcify.
• B: Brucellosis can look like TB in the spine, with both sparing the intervertebral disc space. Brucellosis can be associated with unpasteurized milk (such as from the Amish) or other farm exposures.
• C: Taenia soleum can be ingested as their larvae directly from undercooked pork (intestinal tapeworm). Cysticercosis refers to ingestion of eggs which then hatch within your body after which the larvae migrate throughout the body, forming encysted cysticerci. Adult onset seizures in a patient exposure to such risk factors should raise suspicion for these lesions.
• D: Malaria can be transmitted by anopheles mosquitos predominantly in sub-saharan Africa. Malaria can result in occlusion of capillaries in the brain, kidney, and lungs. CT findings can be normal or represent edema, particularly in the thalamus or white matter. On MRI petechial microbleeds can be seen in regions of infarcted tissue. Nonspecific T2 hyperintensities/FLAIR are also seen.

  Correct Answer! 

• A: Metastatic Disease - typically enhancing lesions.
• B: Sequestered Disc - The lesion is non-enhancing, isointense to disc, and extradural.
• C: Schwannoma - Typically enhance homogeneously.
• D: Meningioma - These lesions are usually intradural extramedullary with homogeneous enhancement.

  Correct Answer! 

• A: Right L5 nerve root has exited the canal under the right L5 pedicle.
• B: Right S1 nerve is the descending nerve root in the right lateral recess at this level and is most likely to be affected by this process.
  - Nerve exits below corresponding disc in T and L spine
  - Nerve exits above corresponding disc in C spine
• C: Left L5 nerve exits through the left L5-S1 neuroforamina
• D: Left S1 nerve is in the left lateral recess at this level but not affected by the process marked by the arrow