Bulging Fontanelle

Bulging FontanelleWe are all very smart people (objectively, this is a true statement).  Sometimes, however, we can outsmart ourselves.  Don’t strain yourself too much to determine how the laws of thermodynamics may have lead a neonate to be febrile; rather, just do the LP! Additionally, don’t do complex calculus on the results from the traumatic LP; just count the number of white blood cells and be conservative.  If you want to contemplate the utility of urine studies based on duration of illness, that is an excellent use of your neurons; however, overanalyzing what to do with the child who has a Bulging Fontanelle and Fever will not leave you feeling smarter.

 

Bulging Fontanelle: Basics

  • There are 6 Fontanelles, but only two are clinically apparent.
    • Anterior: 4-6 cm in dimension; closure – 4th – 26th month of life
    • Posterior: 1-2 cm in dimension; closure – 1st – 2nd month of life
    • Mastoid x 2, Sphenoid x 2
  • Position of child matters:
    • You should palpate the fontanelle with the child in upright position.
    • Feeling the fontanelle with child supine may cause it to feel full when it is not truly abnormal.
  • Position of the fontanelle matters:
    • The fontanelle should normally be slightly sunken relative to the upper table of the skull.
    • A fontanelle that is even with the upper level of the skull or above it is abnormal.
  • Pulsations are normal – usually represent peripheral pulses.

 

Bulging Fontanelle: Common Benign Causes

Before we get too crazy… let us be reasonable and consider some common causes… but, know that these should be transient.

  • Supine (or Trendelenburg) Position
    • Gravity works
    • Hydrostatic pressure will cause a supine child’s fontanelle to be “full.”
  • Coughing
  • Vomiting
  • Crying
  • Recent Vaccinations have also been associated with bulging fontanelle, but no causal link known and often determined after ruling out badness. [Sreedhar, 2013; Freedman, 2005]

 

Bulging Fontanelle: Super Bad

  • Meningitis/Meningoencephalitis
  • Space Occupying Lesion (ex, AVMs, tumors, intracranial abscess)
  • Intracranial Hemorrhage (ex, Non-accidental trauma, Trauma)
  • Hydrocephalus
  • Hypoxic-Ischemic Injury

 

Bulging Fontanelle: Other Badness

 

Bulging Fontanelle: Evaluation

  • Step 1: Be Reasonable.
    • Ensure that we are not dealing with one of the Common Benign Causes.
  • Step 2: Let’s not outsmart ourselves!
    • Yes, there are cases of benign idiopathic intracranial hypertension… [Goldberg, 2013; Barry, 1989]
    • Yes, there are potential non-emergent causes…
    • Yes, work-ups often reveal no significant pathology, thankfully, but the potential to miss mass or meningitis is real.
  • Step 3: Image brain.
    • In extremely well appearing and afebrile children, may consider close outpatient follow-up and possible MRI.
    • If you are even slightly uncertain about the wellness of the child, don’t outsmart yourself… get the image now.
      • One study found 36% of patients with bulging fontanelles had abnormal neuro-imaging. [Tu, 2005]
      • High risk factors were: Fever and Age < 2 months OR Abnormal Neuro Finding
  • Step 4: Consider the Lumbar Puncture
    • Yes, a small percentage of febrile children with bulging fontanelle have bacterial meningitis, but a more substantial percentage (26.7%) have viral meningitis. [Shacham, 2009]
    • Again… don’t outsmart yourself… if there is no contraindication, get the CSF. [Beri, 2011]
    • Measuring an opening pressure can also add valuable information.

 

References

Raju SS1, Chacko B. Transient bulging fontanelle after measles vaccination. Indian Pediatr. 2014 Aug;51(8):673. PMID: 25129011. [PubMed] [Read by QxMD]
Goldberg EM1. Fever and bulging fontanelle mimicking meningitis in an infant diagnosed with benign intracranial hypertension. Pediatr Emerg Care. 2013 Apr;29(4):513-4. PMID: 23558272. [PubMed] [Read by QxMD]

Shacham S1, Kozer E, Bahat H, Mordish Y, Goldman M. Bulging fontanelle in febrile infants: is lumbar puncture mandatory? Arch Dis Child. 2009 Sep;94(9):690-2. PMID: 19531528. [PubMed] [Read by QxMD]

Freedman SB1, Reed J, Burwen DR, Wise RP, Weiss A, Ball R. Transient bulging fontanelle after vaccination: case report and review of the vaccine adverse event reporting system. J Pediatr. 2005 Nov;147(5):640-4. PMID: 16291356. [PubMed] [Read by QxMD]

Green AM, Walsh CB. Investigational protocols and physician liability. J Clin Psychopharmacol. 1992 Jun;12(3):210-2. PMID: 1629389. [PubMed] [Read by QxMD]
Barry W, Lenney W, Hatcher G. Bulging fontanelles in infants without meningitis. Arch Dis Child. 1989 Apr;64(4):635-6. PMID: 2751342. [PubMed] [Read by QxMD]
Silver W, Kuskin L, Goldenberg L. Bulging anterior fontanelle. Sign of congestive heart failure in infants. Clin Pediatr (Phila). 1970 Jan;9(1):42-3. PMID: 5410370. [PubMed] [Read by QxMD]

Sean Fox

I enjoy taking care of patients and I finding it endlessly rewarding to help train others to do the same. I trained at the Combined Emergency Medicine and Pediatrics residency program at University of Maryland, where I had the tremendous fortune of learning from world renown educators and clinicians. Now I have the unbelievable honor of working with an unbelievably gifted group of practitioners at Carolinas Medical Center. I strive every day to inspire my residents as much as they inspire me.

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9 Responses

  1. MM says:

    Interestingly, I just read your morsel as I had a 7week old patient present with enlarging posterior fontanelle to our ED – when you refer to neuroimaging, is CT adequate? And also, does this apply to posterior fontanelle issues also?

    • Sean Fox says:

      Yes, posterior fontanelle fullness would lead to similar considerations as anterior fontanelle fullness. As for imaging… It somewhat depends on your suspicion for the underlying cause as well as ease of outpatient imaging. If concern high for possible hemorrhage, I’d get CT. U/S is another option as the ventricles can be imaged via the open fontanelle, but may not view all areas well. Others advocate for MRI… I’d reserve this for lower concern for acute issues.

  2. Interesting post! Thanks for your sharing it!

  3. Holly N says:

    I have legal guardianship of a three year old niece and her 4 siblings.
    Yesterday they had a mandatory visit with their bio mother. The 15 yr old and mother got in a fight, n the bio mom pushed 3yrold hard into the arm of couch. She has been complaining of headaches since returning. Her soft spot on top of her head is very firm and seems to be bulging since last combing her hair. Any thoughts!? I can’t seem to find any answers online other then trama can cause bulging. What should I do!?????

    • Sean Fox says:

      Holly N, officially I cannot give medical advice out over the Internet. I will say that it would be unusual for a 3 year old to have an open fontanelle still (the front one usually has closed by 2 years of age). If you are concerned, you should bring the child to the primary care physicians.
      Thank you, Sean

  4. milder says:

    Hi my son’s fontanelle when he asleep it’s bulging and wen he wakes up it’s normal is there a problem . He was addmited once and they did all kind of test even a lumber punsher and he didn’t have meningitis.

    • Sean Fox says:

      Thank you for your comment. Officially, I cannot provide medical advice; however, as was noted in the post, Gravity Works… so when an infant is lying down, the “column of water” (Cerebral Spinal Fluid) will cause a bulging of the fontanelle and that is normal. When an infant sits/ is held up right, then the pressure should decrease and the fontanelle should return to the normal position. It is when the fontanelle is bulging while in upright position, or when it is associated with other physical abnormalities, that this should raise the most concern.
      -sean

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