Rapid neurological deterioration associated with minor head trauma in chronic hydrocephalus

Atlantoaxial Subluxation Secondary to Unstable Os Odontoideum in a Patient With Arrested Hydrocephalus Due to Congenital Aqueductal Stenosis: A Case Report

BACKGROUND

In a small percentage of children born with congenital hydrocephalus, enlargement of the head and the presence of ventriculomegaly may halt and ultimately stabilize the condition designated as arrested hydrocephalus. Arrested hydrocephalus in children is typically due to congenital aqueduct stenosis, which can be described appropriately as a stasis existing within the channel between the third and fourth ventricles. Os odontoideum (OO) is an uncommonly occurring pathology at the craniovertebral junction. Although the clinical and radiologic features of its existence and the therapeutic options for its pathology have been widely discussed within the medical literature, its true etiology has been a source of divisive debate, proposing both a traumatic as well as a congenital mechanism. The etiology of OO has been heartily debated in the literature for several years as well. Most authors have come to support a posttraumatic causality. However, strong evidence exists to support a congenital origin to this rarely observed malformation.

METHODS

Within this case study we present a 24-year-old woman with atlantoaxial subluxation that exists secondary to an orthotropic OO. The patient had a history of arrested hydrocephalus due to congenital aqueductal stenosis beginning in early childhood. She presented with normal intelligence and was neurologically without deficits before the occurrence of an atlantoaxial dislocation. Unfortunately, the pathology was initially misdiagnosed as a decompensation state of the arrested hydrocephalus, and after 8 months the patient became wheelchair bound. Following this unfortunate event the correct diagnosis was ultimately uncovered. Subsequently a C2-1 instrumentation procedure resulted in excellent alignment and fusion.

CONCLUSIONS

To the best of our knowledge, this is the first example of an aqueduct stenosis in the setting of an existing OO, a combination that might be another clue in favor of a congenital etiology.

Helmetlike skull deformity with a large arachnoid cyst

BACKGROUND

It is not difficult to find localized skull ballooning or macrocrania in patients with intracranial arachnoid cysts. However, there have been no previous reports regarding large localized skull protuberant deformities resembling a war helmet. The authors report with a review of literature a case of an adult with helmetlike skull deformity resulting from a large supratentorial arachnoid cyst.

CASE DESCRIPTION

A 35-year-old man presented with a large head deformity since his early childhood that had been the result of gradual progression from infantile macrocrania. He also had mental retardation, sixth cranial nerve palsy with recent aggravation of headache, reduced activity, poor voiding control, and walking disturbance. Magnetic resonance imaging of the head showed hydrocephalus with a large supratentorial arachnoid cyst located in the bilateral parietooccipital area compressing the hemisphere anteriorly, and the tentorium and cerebellum inferiorly. Magnetic resonance venogram demonstrated low-lying short transverse and lateral sinuses, and the superior sagittal sinus and falx were displaced to the right side. Radioisotopic cisternogram showed nonfilling of the isotope in the bilateral parietooccipital area. Cerebrospinal fluid pressure measured by lumbar puncture was 17 cm H(2)O. We tentatively diagnosed the condition as normopressure hydrocephalus with a large supratentorial arachnoid cyst. His headache, reduced activity, poor voiding control, and walking disturbance improved after a cystoperitoneal shunt.

CONCLUSIONS

This might suggest that large arachnoid cysts found in childhood should be treated for prevention of skull deformity and late aggravation of increased intracranial pressure.

Chronic hydrocephalus in adults

Chronic hydrocephalus is a complex condition, the incidence of which increases with increasing age. It is characterised by the presence of ventricular enlargement in the absence of significant elevations of intracranial pressure. The clinical syndrome may develop either as a result of decompensation of a "compensated" congenital hydrocephalus, or it may arise de novo in adult life secondary to a known acquired disturbance of normal CSF dynamics. The latter may be due to late onset acqueductal stenosis or disruption of normal CSF absorptive pathways following subarachnoid hemorrhage or meningitis ("secondary" normal pressure hydrocephalus (NPH)). In some cases the cause of the hydrocephalus remains obscure ("idiopathic" NPH). In all forms of chronic hydrocephalus the clinical course of the disease is heavily influenced by changes in the brain associated with aging, in particular cerebrovascular disease. Recent research has challenged previously held tenets regarding the CSF circulatory system and this in turn has led to a radical rethinking of the pathophysiological basis of chronic hydrocephalus.