Halo Sign

Halo sign, or double-ring sign was taught as a method to determine whether bloody discharge from the ears or nose contained CSF. This test uses the principle of chromatography: different components of a fluid mixture separates as they are absorbed through a material.

“acute halo sign in the setting of trauma indicates a dural leak and a bony defect/fracture occurrence… the halo sign may be seen when cerebrospinal fluid separates from blood on filter paper or on bed linen”

The picture above was published in Emergency Medicine in 2008 showing that blood and CSF separates on bed linen – forming a “halo ring sign”

The value of this sign has been debated and considered neither sensitive nor specific for CSF. It is consistently visible when CSF was mixed with blood at a concentration of 30-90%. Therefore, the absence of halo sign does not exclude a CSF leak, as a CSF:blood mixture <30% would not produce this sign.

Furthermore, other fluids mixed with blood can also produce the characteristic halo / double- ring, including:

• normal rhinorrhea fluid
• tap water
• saline

This sign can occur on bed linen, on filter paper, on absorbent paper and coffee filters.

References:

Burns, B. (2008). Images in Emergency Medicine. Annals Of Emergency Medicine, 51(6), 704-706. doi: 10.1016/j.annemergmed.2007.08.028

Ray, A. (2009). Halo Sign Is Neither Sensitive Nor Specific For Cerebrospinal Fluid Leak. Annals Of Emergency Medicine, 53(2), 288. doi: 10.1016/j.annemergmed.2008.06.474

Classification and Severity of Diabetes Insipidus

Interesting classification of DI, taken from Neurology India, groups DI into mild and severe based on some clinical and lab findings.

 

 

This was their protocol for diagnosis and management of DI in patients who underwent craniopharyngioma surgery.

 

Protocol for diabetes insipidus

• Diagnosis:  UO > 4ml/kg/h over 6 h perior OR Na >145 mEq/L with USG <1.005
• Monitoring
  • if drowsy, unable to drink – measure Is and Os hourly, sum every 6 hours
  • Foley until UO reasonably controlled
  • intraop Na if surgery >6h determines type of IV fluids and if pitressin required in OR
  • measure Na q6h day 1
  • measure Na q12h day 2 until stable x 3 days
  • measure Na daily x 1 week
• Treatment
  • Fluids until patient is awake and demonstrates intact thirst mechanism
    • 0.45% saline when UO 4-6 ml/Kg/h
    • D5W when UO >6ml/kg/h
  • DDAVP
    • day 1 – 5 unit IV boluses of pitressin
    • started as early as possible, usually on 2nd day, oral DDAVP 100 ug tablets of fractions of tablets
• Adequacy of control
  • based on serum Na rather than Is and Os
    • check frequency >150 or <130 or inc/dec by >10mEg/L in 1 day

 

Other pearls:

• Adipsia may be complication of hypothalamic damage
  • diminished thirst sensation
  • higher risk of developing hpyernatremia
  • require round the clock DDAVP
  • need to be trained to drink 2-3L water per day
  • gradually resolves with partial or complete thirst recovery by 9 months
• Polydipsic with high UO
  • patient compensating with increased PO intake, normal or low Na
  • at risk for water intoxication or hyponatremia
  • use oral rehydration solution rather than plain water

 

Reference:

Chacko, AriG et al. “Evaluation Of A Protocol-Based Treatment Strategy For Postoperative Diabetes Insipidus In Craniopharyngioma”. Neurology India 63.5 (2015): 712.