Bulging fontanelle: Difference between revisions

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== Pathophysiology==
==Background==
[[File:Sutures from top.png|thumb|Neonatal suture anatomy.]]
*Fontanelles are fibrous, membrane-covered gaps between cranial bones<ref>Kiesler J, Ricer R. The abnormal fontanel. Am Fam Physician. 2003 Jun 15;67(12):2547-52. PMID 12825844</ref>
*A newborn has six fontanelles: anterior, posterior, two mastoid, and two sphenoid
**Anterior and posterior are the most prominent
**The posterior fontanelle usually closes by 1-2 months of age
**The anterior fontanelle usually closes between 7-19 months of age
*A bulging fontanelle represents [[Management of Elevated Intracranial Pressure|increased intracranial pressure]], which may be transient and either benign or malignant
*Key EM concern: [[meningitis (peds)|meningitis]] is the most critical diagnosis to rule out in a febrile infant with a bulging fontanelle<ref>Freedman SB, et al. 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</ref>
*Meticulous history and physical is essential to guide management


Fontanelles are fibrous membrane-covered gaps between cranial bones. A newborn has six fontanelles: anterior, posterior, two mastoid, and two sphenoid. The most prominent are the anterior and posterior fontanelles
==Clinical Features==
===Normal Fontanelle===
*Soft, flat, or slightly concave when infant is upright and calm
*May briefly bulge with crying, coughing, or Valsalva maneuver — this is normal and transient
*Sunken fontanelle suggests [[dehydration]]


A bulging fontanelle represents [[Management of Elevated Intracranial Pressure|increased intracranial pressure]], which may be transient, benign, or malignant. The most commonly considered etiologies include [[Meningitis]], space-occupying lesion, cerebral edema, and [[Intracranial Hemorrhage (Main)|hemorrhage]] (spontaneous, non-accidental, or traumatic). A meticulous history and physical is essential to guide management of these infants.
===Abnormal (Bulging) Fontanelle===
*Tense, convex, non-pulsatile fontanelle when infant is calm and upright
*May feel firm or "full" to palpation
*Assess with infant calm and in upright position (crying and supine position can cause false bulging)


*The posterior fontanelle usually closes by 1-2 months of age.
===Associated Findings===
*Fever + bulging fontanelle → meningitis until proven otherwise
*Irritability, high-pitched cry, poor feeding, vomiting
*Lethargy, altered mental status, seizures (late signs)
*"Sunset" eyes (downward gaze deviation — hydrocephalus)
*Split sutures, rapidly increasing head circumference (increased ICP, hydrocephalus)
*Bruising, retinal hemorrhages → consider [[non-accidental trauma|NAT]]
*Papilledema (though difficult to assess in infants)


*The anterior fontanelle usually closes between 7-19 months of age.
===Red Flags===
*Fever + bulging fontanelle (meningitis — requires LP)
*Altered mental status or seizures
*Rapidly enlarging head circumference
*Signs of non-accidental trauma (bruises, retinal hemorrhages)
*Focal neurologic deficits
*Apnea or bradycardia


== Differential Diagnosis ==
==Differential Diagnosis==
*[[Meningitis (Peds)|Meningitis]]
===Infectious (Most Urgent)===
*[[Encephalitis]]
*'''[[Meningitis (Peds)|Meningitis]]''' — must rule out in febrile infant
*Meningo-encephalitis
*[[Encephalitis]] / meningoencephalitis
*[[Congestive Heart Failure]]  
*[[Brain abscess]]
*Space-occupying lesions
 
*Thyroid disorders
===Increased ICP===
*[[Intracranial Hemorrhage (Main)|Intracranial Hemorrhage]]
*[[Hydrocephalus]] (congenital or acquired)
*Parathyroid disorders
*[[Intracranial Hemorrhage (Main)|Intracranial hemorrhage]] (traumatic or non-accidental trauma)
*[[Brain Abscess]]
*[[Intracranial mass|Space-occupying lesions]] (tumor)
*[[Diabetic Ketoacidosis]]
*Dural sinus thrombosis
*Hypervitaminosis A
*[[Idiopathic Intracranial Hypertension|Idiopathic intracranial hypertension (pseudotumor cerebri)]]
*Anemia
 
*[[Lead Toxicity|Lead encephalopathy ]]
===Metabolic/Endocrine===
*[[Leukemia (Peds)|Leukemia]]
*[[Diabetic ketoacidosis]]
*Inborn errors of metabolism
*[[Inborn errors of metabolism]]
*Thyroid disorders (hypothyroidism)
*Parathyroid disorders (hypoparathyroidism)
*[[Vitamin A toxicity|Hypervitaminosis A]]
*[[Uremia]]
*[[Uremia]]
*Trauma
*[[Roseola Infantum]]
*[[Vaccination Schedule|Vaccinations]]
*Shigella
*[[Idiopathic Intracranial Hypertension|Idiopathic Intracranial Hypertension (Pseudotumor Cerebri)]]
*Dural sinus thrombosis
*Viral syndromes
*Hydrocephalus
==Treatment==
Standard approach:


#[[Head CT]] followed by [[Lumbar Puncture]] if not contraindicated by CT findings
===Other===
#Record opening and closing pressures in children is warranted
*[[Leukemia (Peds)|Leukemia]] (bone marrow infiltration)
*[[Anemia]] (severe)
*[[Lead toxicity|Lead encephalopathy]]
*[[Congestive Heart Failure]] (with cerebral venous congestion)
*[[Roseola infantum]] (benign, self-limited — may cause transient bulging fontanelle)
*Post-[[Vaccination Schedule|vaccination]] (benign, self-limited — rare)
*[[Shigella]] (meningismus without meningitis)
*[[Viral syndrome]]s


''for a well appearing, asymptomatic, afebrile child with bulging fontanelle, an observation period may be appropriate.  In these stable children, if a subacute condition such as an asymptomatic space-occupying lesion is likely, he may benefit from admission and MRI''
===Benign/Transient===
*Crying, Valsalva, supine positioning (normal variant — resolves when calm and upright)


== Sources==
==Evaluation==
Baqui AH, de Francisco A, Arifeen SE, Siddique AK, Sack RB. Bulging fontanelle after supplementation with 25,000 IU of vitamin A in infancy using immunization contacts. Acta Paediatr. 1995 Aug;84(8):863-6.
===Assessment===
*Examine fontanelle with infant calm and upright
*Head circumference and comparison to prior measurements
*Full neurologic exam (tone, reflexes, mental status)
*Fundoscopic exam if possible (retinal hemorrhages → NAT)
*Assess vital signs including temperature


Beri S, Hussain N. Bulging fontanelle in febrile infants: lumbar puncture is mandatory. [Letter]. Arch Dis Child. 2011; 96 (1):109.
===Standard Approach===
*[[Head CT]] (non-contrast): evaluate for hemorrhage, hydrocephalus, mass, edema
**Obtain before LP if concern for mass lesion or elevated ICP
*'''[[LP]]''' (lumbar puncture): if not contraindicated by CT findings
**Opening pressure, CSF cell count, glucose, protein, Gram stain, culture
**Send viral studies if encephalitis suspected
**Consider HSV PCR in neonates
*[[CBC]], [[BMP]], blood cultures
*Blood glucose
*Consider metabolic workup if no infectious or structural cause identified


Biswas AC, Molla MA, Al-Moslem K. A baby with bulging anterior fontanelle. Lancet. 2000; 356(9224):132.
===When to Obtain Imaging Before LP===
*Focal neurologic deficits
*Papilledema
*Signs of severely elevated ICP (altered mental status, bradycardia, hypertension)
*History of shunt (shunt malfunction)
*History of CNS disease or mass


Long SS. Transient bulging fontanelle after immunization. J Pediatr. 2005; 147(5):A3
==Management==
*Treat underlying pathology
*Suspected meningitis: empiric antibiotics should NOT be delayed for imaging or LP
**<1 month: [[ampicillin]] + [[cefotaxime]] (or [[ceftriaxone]] if >28 days) +/- acyclovir
**1-3 months: [[vancomycin]] + [[ceftriaxone]] (or cefotaxime)
**>3 months: [[vancomycin]] + [[ceftriaxone]]
*Elevated ICP: see [[Management of Elevated Intracranial Pressure]]
**Head of bed elevation 30 degrees
**Neurosurgical consultation for hydrocephalus or mass
*Herpes encephalitis: IV [[acyclovir]] — start empirically in neonates with any suspicion
*Intracranial hemorrhage: neurosurgical consultation, correct coagulopathy


Opfer K. The bulging fontanelle. Lancet. 1963 Jan 12;1(7272):116.
==Disposition==
===Admit===
*All infants with bulging fontanelle + fever (pending LP results and cultures)
*Suspected meningitis or encephalitis
*Intracranial hemorrhage or mass
*New hydrocephalus
*Non-accidental trauma (also alert child protective services)
*Altered mental status or seizures


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.
===Discharge===
*Discharge is rare — only if clearly benign and transient cause identified (e.g., post-vaccination in well-appearing infant with normal exam)
*Must have reliable caregivers and immediate return access
*Return precautions: fever, poor feeding, irritability, vomiting, seizure, lethargy


Shacham S, Kozer E, Bahat H, Mordish Y, Goldman M. Bulging fontanelle in febrile infants: is lumbar puncture mandatory? Arch Dis Child. 2009;94:690–692.
==See Also==
*[[Meningitis (peds)]]
*[[Management of Elevated Intracranial Pressure]]
*[[Hydrocephalus]]
*[[Non-accidental trauma]]
*[[Infant fever]]


==References==
<references/>


[[Category:Pediatrics]]
[[Category:Pediatrics]]
[[Category:Symptoms]]
[[Category:Neurology]]

Latest revision as of 10:44, 22 March 2026

Background

Neonatal suture anatomy.
  • Fontanelles are fibrous, membrane-covered gaps between cranial bones[1]
  • A newborn has six fontanelles: anterior, posterior, two mastoid, and two sphenoid
    • Anterior and posterior are the most prominent
    • The posterior fontanelle usually closes by 1-2 months of age
    • The anterior fontanelle usually closes between 7-19 months of age
  • A bulging fontanelle represents increased intracranial pressure, which may be transient and either benign or malignant
  • Key EM concern: meningitis is the most critical diagnosis to rule out in a febrile infant with a bulging fontanelle[2]
  • Meticulous history and physical is essential to guide management

Clinical Features

Normal Fontanelle

  • Soft, flat, or slightly concave when infant is upright and calm
  • May briefly bulge with crying, coughing, or Valsalva maneuver — this is normal and transient
  • Sunken fontanelle suggests dehydration

Abnormal (Bulging) Fontanelle

  • Tense, convex, non-pulsatile fontanelle when infant is calm and upright
  • May feel firm or "full" to palpation
  • Assess with infant calm and in upright position (crying and supine position can cause false bulging)

Associated Findings

  • Fever + bulging fontanelle → meningitis until proven otherwise
  • Irritability, high-pitched cry, poor feeding, vomiting
  • Lethargy, altered mental status, seizures (late signs)
  • "Sunset" eyes (downward gaze deviation — hydrocephalus)
  • Split sutures, rapidly increasing head circumference (increased ICP, hydrocephalus)
  • Bruising, retinal hemorrhages → consider NAT
  • Papilledema (though difficult to assess in infants)

Red Flags

  • Fever + bulging fontanelle (meningitis — requires LP)
  • Altered mental status or seizures
  • Rapidly enlarging head circumference
  • Signs of non-accidental trauma (bruises, retinal hemorrhages)
  • Focal neurologic deficits
  • Apnea or bradycardia

Differential Diagnosis

Infectious (Most Urgent)

Increased ICP

Metabolic/Endocrine

Other

Benign/Transient

  • Crying, Valsalva, supine positioning (normal variant — resolves when calm and upright)

Evaluation

Assessment

  • Examine fontanelle with infant calm and upright
  • Head circumference and comparison to prior measurements
  • Full neurologic exam (tone, reflexes, mental status)
  • Fundoscopic exam if possible (retinal hemorrhages → NAT)
  • Assess vital signs including temperature

Standard Approach

  • Head CT (non-contrast): evaluate for hemorrhage, hydrocephalus, mass, edema
    • Obtain before LP if concern for mass lesion or elevated ICP
  • LP (lumbar puncture): if not contraindicated by CT findings
    • Opening pressure, CSF cell count, glucose, protein, Gram stain, culture
    • Send viral studies if encephalitis suspected
    • Consider HSV PCR in neonates
  • CBC, BMP, blood cultures
  • Blood glucose
  • Consider metabolic workup if no infectious or structural cause identified

When to Obtain Imaging Before LP

  • Focal neurologic deficits
  • Papilledema
  • Signs of severely elevated ICP (altered mental status, bradycardia, hypertension)
  • History of shunt (shunt malfunction)
  • History of CNS disease or mass

Management

Disposition

Admit

  • All infants with bulging fontanelle + fever (pending LP results and cultures)
  • Suspected meningitis or encephalitis
  • Intracranial hemorrhage or mass
  • New hydrocephalus
  • Non-accidental trauma (also alert child protective services)
  • Altered mental status or seizures

Discharge

  • Discharge is rare — only if clearly benign and transient cause identified (e.g., post-vaccination in well-appearing infant with normal exam)
  • Must have reliable caregivers and immediate return access
  • Return precautions: fever, poor feeding, irritability, vomiting, seizure, lethargy

See Also

References

  1. ↑ Kiesler J, Ricer R. The abnormal fontanel. Am Fam Physician. 2003 Jun 15;67(12):2547-52. PMID 12825844
  2. ↑ Freedman SB, et al. 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
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