J Korean Child Neurol Soc.  2011 Dec;19(3):231-239.

A1 Segment Hypoplasia/aplasia Detected by Magnetic Resonance Angiography in Neuropediatric Patients

• Han YK
• Kim S
• Yoon CS
• Lee YM
• Kang HC
• Lee JS
• Kim HD

Abstract

PURPOSE
A variation in the circle of Willis is not so common, but the most frequent type is hypoplasia/aplasia of the precommunicating anterior cerebral arteries (A1 segment). We aimed to examine the incidence and the clinical significance of A1 segment hypoplasia/aplasia in neuropediatric patients.
METHODS
We retrospectively studied children with A1 segment hypoplasia/aplasia in brain magnetic resonance angiography (MRA) and compared the clinical and radiological aspects between children with A1 segment hypoplasia/aplasia alone and with other variations in the circle of Willis.
RESULTS
Among 301 patients, 34 patients (11.3%) had A1 segment hypoplasia/aplasia. They presented neurological symptoms such as chronic headache, dizziness and visual disturbance. Seven (20.6%) had family history of neurological illness. Twenty seven (79.4%) had A1 segment hypoplasia/aplasia only, and seven (20.6%) had another vascular abnormality. Seven (20.6%) showed abnormal brain magnetic resonance angiography (MRI) results, cerebral atrophy being the most frequent (n=5, 14.7%). The incidence of abnormal brain MRI was 11.1% (n=3) in single vascular abnormality and 57.1% (n=4), significantly higher (p-value 0.02) in combined abnormality group.
CONCLUSION
Structural alterations in the cerebral vasculature in children have important pathophysiological and clinical implications. Evaluation of variations in the circle of Willis, especially of A1 segment hypoplasia/aplasia using MRA is recommended.

Keyword

Circle of Willis; A1 segment; Hypoplasia; Aplasia; Magnetic resonance angiography

MeSH Terms

Anterior Cerebral Artery
Atrophy
Brain
Child
Circle of Willis
Dizziness
Headache Disorders
Humans
Incidence
Magnetic Resonance Angiography
Magnetic Resonance Spectroscopy
Magnetics
Magnets
Retrospective Studies