Benign external hydrocephalus: a review, with emphasis on management

Abstract

Benign external hydrocephalus in infants, characterized by macrocephaly and typical neuroimaging findings, is considered as a self-limiting condition and is therefore rarely treated. This review concerns all aspects of this condition: etiology, neuroimaging, symptoms and clinical findings, treatment, and outcome, with emphasis on management. The review is based on a systematic search in the Pubmed and Web of Science databases. The search covered various forms of hydrocephalus, extracerebral fluid, and macrocephaly. Studies reporting small children with idiopathic external hydrocephalus were included, mostly focusing on the studies reporting a long-term outcome. A total of 147 studies are included, the majority however with a limited methodological quality. Several theories regarding pathophysiology and various symptoms, signs, and clinical findings underscore the heterogeneity of the condition. Neuroimaging is important in the differentiation between external hydrocephalus and similar conditions. A transient delay of psychomotor development is commonly seen during childhood. A long-term outcome is scarcely reported, and the results are varying. Although most children with external hydrocephalus seem to do well both initially and in the long term, a substantial number of patients show temporary or permanent psychomotor delay. To verify that this truly is a benign condition, we suggest that future research on external hydrocephalus should focus on the long-term effects of surgical treatment as opposed to conservative management.

Prevalence of Subdural Collections in Children with Macrocrania

“…A male predominance in both the overall group of patients with macrocrania and those with enlarged SS was noted, consistent with prior studies. 2 Subjects with macrocrania and enlarged SS were younger than those subjects with normal SS, a finding described in other studies of BESS. 2 Enlarged SS typically normalize by 2-3 years of age in BESS.…”

“…Children Ͼ24 months of age were excluded because BESS is typically much less prevalent after this time. 2 Subjects with technically nondiagnostic examinations were excluded.…”

“…In the setting of large or rapidly growing head circumference (HC), normal or mildly enlarged ventricles with enlargement of the SS, particularly over the frontal lobes, these children are usually diagnosed with "benign enlargement of the subarachnoid spaces" (BESS). [1][2][3][4][5] Children with BESS typically have no neurologic or long-term developmental abnormalities with resolution of clinical and imaging findings within the first 2 years of life. 6 Some investigators have suggested that children with macrocrania and enlargement of the SS may be at increased risk for subdural hemorrhage (SDH) after minimal or no trauma.…”

Benign External Hydrocephalus in Infants

“…Several authors describe a transient delay of psychomotor development during childhood. Although most children with external hydrocephalus seem to do well both initially and in the long term, an important number of patients show temporary or permanent psychomotor delay 8 .…”

“…The most specific neuroradiological feature in BEH is an extension of the subarachnoid spaces in the frontal lobes with a normal or only slight increase in ventricular volume as can be appreciated by transfontanellar ultrasound, MRI and CT scan. Transfontanellar ultrasonography can easily make the diagnosis of BEH by evaluating the skull-to-cortex distance that in children with this condition is greater than 5 mm 11 . Transfontanellar ultrasound is also useful in assessing the presence of ventriculomegaly in infants, especially allowing a differential diagnosis between a benign enlargement of the subarachnoid space and subdural fluid collection caused by meningitis, haemorrhage or trauma.…”