The occipital condyle is frequently being drilled to expose lesions ventral to the brainstem. From our study, it is evident that the occipital condyle can be safely drilled for a distance of 12 mms from the posterior margin before encountering the hypoglossal canal. In 20% of the skulls the occipital condyle protrudes significantly into the foramen magnum. Wide and sagittally inclined occipital condyles, medially protruberant occipital condyles along with a foramen magnum index of more than 1.2 will require much more extensive bony resection than otherwise. With the availability of recent imaging techniques, it is possible to anticipate the extent of bony resection required in an individual case by using the above mentioned morphometric features.

No abstract

Hydrocephalus is known to be associated with syringomyelia; however, the association between arrested hydrocephalus and syringomyelia has been reported only once before. This presyrinx state is a recently recognized condition that is known to resolve with proper treatment. This case report highlights a rare association between arrested hydrocephalus and the presyrinx state and outlines the implications for treatment and etiopathogenesis. A 6-year-old girl with arrested hydrocephalus presented with a recent history of difficulty in walking despite no antecedent trauma or infection. An examination revealed macrocrania and features of cervical myelopathy, and magnetic resonance (MR) imaging revealed panventriculomegaly with evidence of the presyrinx state on both T1- and T2-weighted images of the cervical spine. The patient underwent a procedure to insert a ventriculoperitoneal shunt that used a mediumpressure system. After the shunt was inserted, the patient's myelopathic symptoms gradually improved over a period of 6 months. Postoperative MR images obtained 1 year later revealed decompression of the ventricular system and complete resolution of the presyrinx state in the cervical spinal cord. Decompensation in arrested hydrocephalus is a well-known phenomenon. This case illustrates the concept that the presyrinx state may be one of the manifestations of decompensated arrested hydrocephalus. The importance of early recognition of this condition and its implications for the pathogenesis of syringomyelia are discussed.

No abstract

We report a case of spontaneous temporary resolution of congenital hydrocephalus due to drainage into the subdural space, which is not a physiological space for cerebrospinal fluid (CSF). This is the first report of spontaneous drainage of CSF into the subdural space, and we term it “ventriculosubdurostomy.” We highlight the fact that spontaneous resolution of hydrocephalus due to drainage into a nonphysiological CSF space is temporary.