Transient Bulging of the Fontanelle in Infants after a Febrile Illness without Central Nervous System Infection

Sul Hee Bae; Young Ok Kim; Sang Jung Kim; Young Jun Son; Young Jong Woo

doi:10.4068/cmj.2010.46.2.117

Abstract

Increased intracranial pressure in infants with open cranial sutures can cause bulging of the anterior fontanelle. This condition is referred to as transient bulging of the fontanelle (TBF) if the bulging anterior fontanelle regresses spontaneously and no specific causes, such as central nervous system infection or a space-occupying lesion, can be identified. This is a different form of idiopathic intracranial hypertension that occurs during infancy. We encountered three infants with TBF who presented with irritability and a bulging anterior fontanelle after a febrile illness. There was no evidence of a central nervous system infection or a space-occupying lesion in any of the three infants. All three patients had normal cerebrospinal fluid (CSF) findings; negative blood, urine, and CSF cultures; and normal brain imaging studies. Associated infections were confirmed in two cases (rotaviral enteritis in one patient and exanthema subitum in the other). The bulging anterior fontanelle improved rapidly after lumbar puncture and resolved completely within 5 days. We report these three patients with TBF along with a review of the medical literature.

Introduction

Bulging of the fontanelle in infants with open cranial sutures is generally regarded as a sign of increased intracranial pressure (ICP).1 The condition is usually associated with serious central nervous system (CNS) pathology, such as meningitis, cerebral hemorrhage, brain abscess, hydrocephalus, or tumors.2 Without any evidence of clinical, laboratory, or radiological intracranial pathology, an increased ICP can be diagnosed as idiopathic intracranial hypertension (IIH), pseudotumor cerebri, or transient bulging of the fontanelle (TBF) of infancy.1,3

Several cases of bulging of the fontanelle or IIH have been reported in children after a febrile illness, such as roseola infantum (also known as exanthema subitum), otitis media, upper respiratory infections,4 or vaccinations.1 In this report, two of the three patients had associated infections (rotaviral enteritis in one patient and exanthema subitum in the other). We report these three cases of TBF subsequent to a previous febrile illness that resolved spontaneously after lumbar puncture (Table 1).

Case Report

1. Patient 1

A 7-month-old girl was admitted to the hospital with a 3-day history of fever and a bulging anterior fontanelle that had been noticed by her parents. Her symptoms included vomiting, poor oral intake, and irritability. Her birth and prior history were noncontributory. Her growth parameters and development were within normal limits. A physical examination revealed a tense and bulging anterior fontanelle with no other abnormal findings (Fig. 1). The patient was initially believed to have meningitis. Therefore, the cerebrospinal fluid (CSF) as well as routine laboratory tests, including blood cell counts and blood chemistry and urine analysis, were evaluated. The CSF opening pressure on lumbar puncture was <20 cmH₂O. The laboratory tests and CSF showed no abnormal findings (Table 1). The blood, CSF, urine, and stool cultures were negative for microorganisms. The brain computed tomography (CT) showed no abnormal findings. Lumbar puncture relieved the bulging of the anterior fontanelle immediately. On the second day of admission, the fever subsided, and on the third day, erythematous nonpruritic maculopapular skin appeared on the trunk and spread to the legs, lasting for 2 days. The patient was discharged on the fifth day and was followed up in the outpatient department (OPD) without recurrence of the anterior fontanelle bulging.

2. Patient 2

A previously healthy 5-month-old girl presented with a 1-day history of fever, vomiting, and irritability. The physical examination revealed anterior fontanelle bulging but no other abnormal findings. The routine laboratory tests upon admission showed no abnormalities in the blood cell count, blood chemistry (including plasma glucose, electrolytes, and C-reactive protein), urine analysis, or CSF examination (Table 1). The CSF opening pressure on lumbar puncture was <20 cmH₂O. There were no signs of infection in the blood, CSF, or urine cultures. Head ultrasonography showed a 1-cm left subependymal cyst but no space-occupying lesion. The anterior fontanelle bulging was reduced promptly after lumbar puncture upon admission, and the fever resolved the next day. The patient was discharged on the third day and followed-up at the OPD for 1 month without recurrence of the bulging of the fontanelle.

3. Patient 3

A 10-month-old boy visited the emergency department with a 4-day history of fever, irritability, and a bulging anterior fontanelle that was associated with coughing, vomiting, and diarrhea. His prior history was noncontributory and his growth parameters were in the normal range. The physical examination was normal except for a hard and tense bulging anterior fontanelle at rest. The routine laboratory findings upon admission showed no abnormalities in blood cell counts, blood chemistry (including plasma glucose, electrolytes, and C-reactive protein), urine analysis, or CSF analysis. Although the results of the CSF cell count, protein, glucose, Gram stain, and rapid bacterial antigen test were normal, the CSF opening pressure on a lumbar puncture was 20 cmH₂O upon admission (Table 1). No bacterial organisms were detected in the blood, CSF, urine, stool, or throat swab cultures. However, a rotavirus was detected in the loose stool by latex agglutination. The ophthalmologic examination showed no papilledema. The brain CT was normal. On the second hospital day, the fever and irritability improved, and the bulging fontanelle also appeared to improve but not completely. Accordingly, on the fourth day, a second lumbar puncture was performed because of continued bulging of the fontanelle, which resulted in rapid resolution, even though the opening CSF pressure on the second procedure had reached 30 cmH₂O. The patient was discharged on the sixth hospital day and was followed up in the OPD over the next 21 days without a recurrence of the fontanelle bulging.

Discussion

Idiopathic intracranial hypertension or pseudotumor cerebri (PTC) is characterized by increased intracranial pressure in the absence of any intracranial lesions,1,3 meningitis, intracranial tumors, hydrocephalus, intracranial infections, dural sinus thrombosis, or hypertensive encephalopathy.1,5,6 IIH can occur at all ages but is found more frequently in obese women or during pregnancy.3 Although there are no specific diagnostic criteria for pediatric IIH,2 a diagnosis of IIH in adults is usually established when the following modified Dandy criteria are met:7 (A) signs and symptoms of increased intracranial pressure; (B) absence of localized findings on the neurological examination; (C) absence of deformity, displacement, or obstruction of the ventricular system in otherwise normal diagnostic studies, except for increased CSF pressure; (D) alert and oriented patient; and (E) no other cause of the increased intracranial pressure identified.

A patient affected by IIH may present with headache, nausea, and vomiting, which are nonspecific symptoms of increased intracranial pressure.3,6,7 Other reported symptoms include blurred vision, diplopia, photophobia, stiff neck,3,6 increasing head size, light-headedness, myalgia, and head tilt.2 However, although rarely reported during the first year of life,8 infants with IIH present with unusual signs or symptoms, such as somnolence, apathy, irritability, or bulging of the anterior fontanelle.2 In infancy, IIH leads to TBF because there are open cranial sutures. The presence of TBF in the absence of any intracranial lesions or CNS infection is indicative of IIH during infancy.1,3

The pathogenesis of IIH or TBF is unknown. IIH is not a disorder with a single causative factor.3 In theory, IIH may be caused by the following factors: parenchymal edema,6 increased cerebral blood volume,3,6 excessive CSF production,6 compromised CSF resorption,9 and venous outflow obstruction.3,6 Some studies have reported TBF or IIH in association with vaccination,1 otitis media,4,9 roseola,4 gastroenteritis, pharyngitis, acute upper respiratory infections,4,9 chickenpox,3 measles,9 and other medical problems including endocrine abnormalities or drugs.2 However, there are no case-control studies to date with definitive causes in children.2

Spontaneous recovery from IIH can occur.2 Some studies have confirmed that spontaneous resolution of IIH appears to be more common in children than in adults.6 In some children, IIH resolves after a single lumbar puncture that reduces the intracranial pressure.1,10 However, children with IIH should be followed as carefully as adults because of the potential for permanent visual loss.3,6 Until recovery, the treatment for IIH depends on the symptoms, and is either medical or surgical, focusing primarily on normalizing the ICP.3 Traditionally, oral acetazolamide, a carbonic anhydrase inhibitor, has been the medication of choice for inhibiting CSF production.3,6 Corticosteroids have also been reported to improve IIH.3,6

In this report, all three infants had a previous febrile illness that was believed to be a viral infection. In two of them, an associated infection was confirmed (rotaviral enteritis in one patient and exanthema subitum in the other) and no other medical diseases were indicated. It is possible that the increased intracranial pressure occurred transiently and was associated with a viral infection without an underlying disease. The bulging anterior fontanelle resolved completely within 5 days after the diagnostic lumbar puncture without other specific treatments, and there was no recurrence during the follow-up period.

In summary, three infants had episodes of TBF without an abnormal intracranial pathology. All had normal blood, CSF, and serum chemistry findings as well as negative blood, urine, and CSF cultures. The cause of the increased intracranial pressure was not found, but all episodes were associated with a febrile illness, in which associated infections were demonstrated in two patients. The patients were diagnosed with TBF of infancy, which is a different form of IIH. These cases show that a nonspecific febrile illness can interfere transiently with the CSF dynamics.