Delayed Cerebral Ischemia (Definition)



Delayed Cerebral Ischemia:

Focal (hemiparesis, aphasia, hemianopia, or neglect) or global (2 points decrease on GCS) neurological impairment lasting for at least 1 hour and/or cerebral infarction, which:
▪ Is not apparent immediately after aneurysm occlusion
▪ Is attributable to ischemia
▪ Is not attributed to other causes (i.e. surgical complication, metabolic derangements) after appropriate clinical, imaging, and laboratory evaluation


Cerebral infarction:

Presence of cerebral infarction on CT or MR scan of the brain within 6 weeks after SAH, or on the latest CT or MR scan made before death within 6 weeks, or proven at autopsy; that is:
▪ Not present on the CT or MR scan between 24 and 48 hours after early aneurysm occlusion
▪ Not attributable to other causes such as surgical clipping or endovascular treatment
▪ Not due to a nonischemic lucency related to a ventricular catheter, intraparenchymal hematoma, or brain retraction injury



Francoeur, Charles L. and Stephan A. Mayer. “Management Of Delayed Cerebral Ischemia After Subarachnoid Hemorrhage”. Critical Care 20.1 (2016): n. pag. Web.

Reflection Coefficient

Movement of solutes across the blood brain barrier depends on the reflection coefficient of the solute.  Reflection coefficient is defined as the selectivity of the blood brain barrier to a particular substance.  Molecules with a reflection coefficient of 1 are excluded by the blood brain barrier.  As shown in the table below, sodium chloride is effectively “reflected back” or excluded by the blood brain barrier compared to the other osmotic compounds listed.



Qureshi, Adnan I. and Jose I. Suarez. “Use Of Hypertonic Saline Solutions In Treatment Of Cerebral Edema And Intracranial Hypertension”. Critical Care Medicine 28.9 (2000): 3301-3313.

Definitions for ICU Infections

Bloodstream infections – (+) blood cultures without evidence of a separate primary source


  • ≥10,000 CFUs, or
  • (+) urinalysis (i.e. (+) leukocyte esterase or nitrate or >5 WBC/mL) and ≥1000 CFU.


  • new infiltrate on CXR and (+) sputum culture or change in respiratory status (increased ventilator support or oxygen requirements)

Sinusitis – purulent nasal discharge with corresponding CT imaging

Ventriculitis – (+) CSF culture

CDAD – diarrhea with (+) C. difficile toxin PCR



Halvorson, Karin et al. “Procalcitonin Is A Poor Predictor Of Non-Infectious Fever In The Neurocritical Care Unit”. Neurocritical Care (2017).  Epublished.

Semantic Paraphasia

meaning of the word is related to that of the intended word

6 different types:


  • Coordinate semantic paraphasias  – same category (tiger for lion)
  • Associate semantic paraphasias – related but not the same category (shoe for foot)
  • Superordinate semantic paraphasias – replaces specific with generalized (fruit for pear)
  • Subordinate semantic paraphasias – replace target word with one that is more specific (rose for flower)
  • Part-whole semantic paraphasias – replace the whole with the part (finger for hand) or part with the whole (leg for foot)
  • Visual semantic paraphasia – replace word with another word that shares same visual features (knife for nail)



Restricted diffusion in occipital lobe with extension to left pulvinar nucleus, with ADC correlation.The typical symptoms of thalamic aphasia consist of fluent output, semantic paraphasias, impairment of comprehension, and normal repetition.



Bruzzone, M. et al “Teaching Neuroimages: Aphasia after infarction of the left pulvinar nucleus.  Neurology 2016 August 23, 87 (8): e82.



Aneurysms in Arteriovenous Malformations


This figure illustrates the types of aneurysms that are associated with a brain AVM

  • A. distal flow-related aneurysm
  • B. distal flow-related aneurysm
  • C. nidal aneurysm
  • D. proximal flow-related aneurysm
  • E. non-flow-related aneurysm



  • Aneurysms – saccular luminal dilatations of the parent feeding vessel
  • Flow-related aneurysm – an aneurysm that lies on a pathway of an artery supplying the AVM
  • Nidal aneurysm – aneurysm that is contiguous with the vascular mass include in the AVM size measurement
  • Proximal aneurysms – located on the vessel or branch points of the circle of Willis or proximal to it (i.e. ICA, ACA, PPCA, A1 or P1, VA or BA)
  • Distal aneurysms – more distal locations beyond the circle of Willis.



“Reporting Terminology For Brain Arteriovenous Malformation Clinical And Radiographic Features For Use In Clinical Trials”. Stroke 32.6 (2001): 1430-1442. Web.

Sepsis Redefined

New recommendations for sepsis was published in the February 2016 issue of JAMA and highlighted at SCCMs 45th Critical Care Congress in Orlando, Florida.

Sepsis is defined as life-threatening organ dysfunction due to a dysregulated host response to infection.  Septic shock is defined as a subset of sepsis in which profound circulatory, cellular and metabolic abnormalities substantially increase mortality.

The new definitions were suggested to reflect the advances made in the pathophysiology, management and epidemiology of sepsis.

The term “severe sepsis” has been removed to highlight the fact that sepsis, by itself, is already a severe condition, making the term severe sepsis redundant.

Organ dysfunction is a key part in the definition of sepsis, and it is the main consideration that elevates uncomplicated infection to sepsis.  Suspicion of infection should prompt a search for organ dysfunction, and organ dysfunction should prompt a search for a focus of infection.

A new diagnostic tool, quickSOFA or qSOFA, was recommended, which consists of 3 simple bedside tests to identify patients at risk for sepsis.  This tool directs physicians to look for these signs: a change in mental status, decrease in SBP <100mm Hg or a respiratory rate >22/min.  Patients with 2 or more of these conditions are at higher risk of prolonged ICU stay or to die in the hospital.  For these patients, clinicians should investigate further for organ dysfunction, initiate or escalate therapy, and consider referral to critical care or increase frequency of monitoring.

The task force identified two new clinical criteria that should be used in diagnosing septic shock:  persistent hypotension requiring vasopressors to maintain MAP>/=65mmHg and blood lactate >2mmol/L despite adequate volume resuscitation.

The report has been designated as “Sepsis-3” (the first two were proposed in 1991 an 2001)