PICA infarction


  • A 35 years old man
  • Known case of DM, HPT
  • Also previously diagnosed as retroviral +ve
  • Presented with sudden onset of headache and generalized body weakness
  • Clinical examination shows GCS 15/15, no muscle weakness
Urgent plain CT brain soft tissue window on the day of admission
Non-contrast CT brain soft tissue window 2 days after admission
Contrast-enhanced CT brain soft tissue window 2 days after admission

CT findings:

  • Initial CT brain done on admission shows no significant finding
  • A repeat CT brain with contrast done 2 days later
  • The CT scan show hypodensity at the posterior inferior part of both cerebellum
  • It is well-defined and do not show enhancement post contrast
MRI brain done on day 5 of admission
DWI and ADC sequences

MRI findings:

  • The cerebellar changes seen as hypointense on T1, hyperintense on T2 and FLAIR (yellow arrows)
  • Involving posterior and inferior cerebelli, more on the right side
  • It shows restricted diffusion
  • No significant mass effect is seen

Diagnosis: PICA (posterior inferior cerebellar) infarction.


  • Cerebellar infarction is relatively uncommon and account forĀ  about 2% of all cerebral infarction
  • PICA is one of the three main arteries that supply the cerebellum
  • PICA is the largest branch of vertebral artery and supplies posterior inferior cerebellum, inferior cerebellar vermis and lateral medulla
  • Vertigo, nausea and truncal ataxia are the most common presenting features
  • MRI is far superior to CT in the sensitivity of acute ischaemic stroke across all vascular territories.
  • In the acute phase T2WI will be normal, but in time the infarcted area will become hyperintense.
  • The hyperintensity on T2WI reaches its maximum between 7 and 30 days. After this it starts to fade.
  • DWI is already positive in the acute phase and then becomes more bright with a maximum at 7 days.
  • DWI in brain infarction will be positive for approximately for 3 weeks after onset
  • ADC will be of low signal intensity with a maximum at 24 hours and then will increase in signal intensity and finally becomes bright in the chronic stage.




Author: radhianahassan