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From the Departments of Neurology (M.W.H., G.R.) and Neurosurgery (G.E.V.), University of Rochester School of Medicine and Dentistry, NY.
Address correspondence and reprint requests to Dr. Marc W. Halterman, Department of Neurology, University of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Box 673, Rochester, NY 14642 Marc_Halterman{at}urmc.rochester.edu
Idiopathic aqueductal stenosis (AS) may account for up to 59% of cases presenting with triventricular noncommunicating hydrocephalus.1 The clinical presentations associated with triventricular hydrocephalus differ depending on age at onset and the acuity of obstruction. Acute syndromes include Parinaud's syndrome (vertical gaze restriction, lid retraction, and pupillary abnormalities), the rostral midbrain syndrome (upward gaze palsy, retraction nystagmus, pyramidal and extrapyramidal signs), and deficits in arousal. In the very young, chronic diencephalic compression can produce the bobble-head doll syndrome (high frequency head movements, limb ataxia, tremor, and cognitive deficits). Resolution of transtentorial pressure gradients by CSF diversion typically produces rapid improvement.2
We describe an adult patient with upper extremity tremor due to decompensated hydrocephalus from AS, who demonstrated improvement following endoscopic third ventriculostomy.
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CASE REPORT |
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 Top. CASE REPORT DISCUSSIONREFERENCES |
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At presentation the tremor was unchanged, but his academic performance had declined and he had frequent headaches. He denied nausea, visual disturbances, weakness, or problems with bladder control. On examination, head circumference measured 62 cm and mild frontal bossing and hypomimia were present. Recall at 5 minutes was impaired (one of three objects), he could not complete serial sevens, and he was unable to provide the date. Language function was intact. Funduscopy was benign, pupils were 3 mm and reactive, and versions were preserved without nystagmus. Strength was full throughout with a spastic catch elicited on elbow extension bilaterally. Neither postural nor rest tremor was elicited, but finger-to-nose testing elicited a bilateral, 4 Hz action tremor, which was worse on the right (see video 1 on the Neurology Web site at www.neurology.org). A postural tremor was present in the right leg with standing. Stride length, arm swing, tandem gait, and turns were preserved.
MRI of the brain demonstrated expanded lateral ventricles, midbrain compression, low lying cerebellar tonsils, and transependymal interstitial edema (figure 1). The cortical mantle was thinned and the fourth ventricle was preserved. While CSF flow studies demonstrated flow across the foramen magnum along both anterior and posterior aspects of the cranio-cervical junction (figure 2A), cross sectional phase contrast MRI documented absent flow in the aqueductal canal, supported by the appearance on sagittal high resolution gradient echo imaging. There were no areas of abnormal gadolinium enhancement. These features were consistent with the diagnosis of AS.3
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Endoscopic third ventriculostomy was performed to arrest progression of the hydrocephalus.4 Ventriculographic guidance provided visualization of the distended architecture of the lateral ventricle and vascular structures (figure 1D). Six months postoperatively, the patient could hold a drinking glass without spilling, and his headaches had resolved. Follow-up MRI studies demonstrated an open ventriculostomy site (figure 2B), and decompression of the lateral ventricles with expansion of the cortical mantle (figure 2, C and D). On examination, the patient's free-recall and dysmetria (video 2) had improved.
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DISCUSSION |
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Top.CASE REPORTDISCUSSIONREFERENCES |
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For all causes of obstructive hydrocephalus, age at the time of diagnosis also exhibits a bimodal distribution with an early peak between months 1 and 4 (23% of cases) with a broader distribution spanning ages 8 to 17. A retrospective analysis of 213 patients (age 1 month to 18 years) with obstructive hydrocephalus found headache, vomiting, psychomotor retardation, and gait disturbances to be the most common presenting symptoms.1 Patients under the age of 30 with chronic AS (present for greater than 6 months) most often complain of headache, while patients over age 63 exhibit dementia, gait disturbance, and urinary incontinence.6 Of note, tremor was present in only 12.5% (3/25) of cases and was seen later in the disease course. Also, patients initially diagnosed and treated for triventricular hydrocephalus can present with parkinsonism without tremor, which responds to dopaminergic therapy and shunt revision.7
Surgical options for AS include shunting, choroid plexectomy, third ventriculostomy, and aqueductoplasty. Intervention may be warranted if a pattern of gradual clinical decline and transependymal edema on imaging are present. Endoscopic third ventriculostomy (ETV) creates a communication between the third ventricle and the subarachnoid space, and is an option in patients older than 6 months of age.8 In a retrospective analysis with 42 months of follow-up, investigators demonstrated that ETV provided durable patency in 90% of patients with AS, excluding cases due to cysts, tumors, or post-hemorrhagic ventriculitis.9 Third ventriculostomy can be performed with success rates between 80 and 100%.10 In cases of late onset AS (n = 31) treated with ETV, improvement occurred in 84% of patients after 26 months.6
While stereotactic approaches have significantly reduced the procedure-related mortality associated with open third ventriculostomy (5% vs 27%), current techniques are associated with rare but fatal vascular injuries.4,11,12 While decompression of the third ventricle, upward deviation of the brainstem, and reduction in the size of the lateral ventricles are predictable changes postoperatively,13 clinical improvement can precede demonstrable radiographic improvement. Improved posture, gait, and cognition were achieved in greater than 50% of patients (32/58) within 2 weeks postoperatively when imaging data were largely unchanged.14
Our experience suggests that late onset AS should be considered in the differential diagnosis for new onset tremor in adolescence. Furthermore, this case supports a role for endoscopic third ventriculostomy in the treatment of AS.
Disclosure: The authors report no conflicts ofinterest.
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