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Posterior fossa extraaxial hematoma may result from small tentorium tears, ruptures of bridging veins, or due to occipital diathesis. A history of birth trauma is often present. Posterior fossa hematoma may present with coma, eye deviation (not altered by lateral head rotation to provoke the doll's head phenomenon or cold caloric testing), and pupillary abnormalities. This presentation may occur after a symptom-free period or immediately after birth. The neonate may develop retrocollis or opisthotonos. Bradycardia and apnea are usually terminal events. Posterior fossa hematoma is diagnosed by CT or MRI of the brain. Treatment is surgical.
Other posterior fossa lesions that may present with signs of mass effects are pontine gliomas and brainstem hemorrhage. They are diagnosed by MRI of the brain. Treatment is dictated by the cause.

Developmental Abnormalities
Cleland-Chiari malformation has three major elements: brainstem displacement, cerebellar dysplasia, and elongation of the fourth ventricles. This anomaly may be associated with myelomeningocele and hydrocephalus. Cleland-Chiari malformation is characterized by feeding difficulties and a weak cry due to medullary dysfunction. Frequent episodes of crying and apnea may occur. Laryngeal stridor may occur during crying and feeding. The diagnosis is established by MRI of the brain (Figure 27.1).

Figure 27.1. Cleland-Chiari malformation. Elongation of the brainstem and beaking of the posterior midbrain.

 

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ventriculus III corporis callosi cervico-medullary junction "kink" elongated fourth ventricle medulla oblongata pons elongated mesencephalon (midbrain) beaked tectum large massa intermedia of the thalamus Two options: (1) click on figure; or (2) pause pointer on structures indicated by arrows (figure must be centered).