Surgical management of cervicomedullary compression in achondroplasia

Abstract

Achondroplasia is often associated with cervicomedullary dysfunction. MRI sagittal imaging was performed to determine whether surgical intervention was necessary to relieve cervicomedullary compression. Cervicomedullary compression was classified into severe and mild types based on the ratios of the brain stem diameter at the foramen magnum, the site of the most severe stenosis to the diameter at the pontomedullary junction and C3 level, where it is normal. This classification was found to be closely correlated with the severity of clinical symptoms and important in determining whether surgical intervention is necessary. Moreover, since the incidence of sudden death is high in patients aged 4 years or younger with achondroplasia, surgical intervention should be considered in all such patients if cervicomedullary compression is present.

The use of gated cine phase contrast and MR venography in achondroplasia

“…Foramen magnum decompression is performed by removal of the posterior lip of the foramen magnum but does not address the exoocciput [14,22]. The posterior arch of C-1 is often removed at the same time along with the ligamentum flavum and dura [14,22]. Dural fenestration and patch angioplasty may be performed if the underlying dural appears to be restrictive at surgery.…”

“…In the other four patients with brain stem compression there was osseous overgrowth of the posterior lip of the foramen magnum, with minimal impingement on the ventral surface of the brain stem. The variability in the site of brain stem compression explains why removal of the posterior lip of the foramen magnum relieves the brain stem compression in some patients while in others removal of the posterior arch of C-1 and regional ligaments is necessary [14,22]. Clinical symptoms suggestive of brain stem compression are often respiratory and include sleep apnea, snoring, and respiratory distress.…”

“…Clinical symptoms suggestive of brain stem compression are often respiratory and include sleep apnea, snoring, and respiratory distress. However, central sleep apnea may not be indicative of brain stem compression and the pattern and location of brain stem compression does not correlate with symptoms [22].…”

“…There is an ongoing debate in the literature about the etiology of hydrocephalus in achondroplasia [13,16,19,21,22]. In 1996, Yamada stated that hydrocephalus could be relieved by foramen magnum decompression [22].…”

“…Infants and young children with achondroplasia may be referred for cranial MR imaging for excessive snoring, sleep apnea, or other symptoms suggestive of brain stem compression, or to allay parental concerns. The MR appearance of the cranio-vertebral junction in achondroplasia has been described [12,22].…”