- Department of Neurosurgery, Virginia Commonwealth University, Medical College of Virginia, Richmond, Virginia, USA
- Department of Emergency Medicine, Virginia Commonwealth University, Medical College of Virginia, Richmond, Virginia, USA
Rafael A. Vega
Department of Neurosurgery, Virginia Commonwealth University, Medical College of Virginia, Richmond, Virginia, USA
DOI:10.4103/2152-7806.116151Copyright: © 2013 Vega RA This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
How to cite this article: Vega RA, Buscher MG, Gonzalez MS, Tye GW. Sonographic localization of a nonpalpable shunt: Ultrasound-assisted ventricular shunt tap. Surg Neurol Int 06-Aug-2013;4:101
How to cite this URL: Vega RA, Buscher MG, Gonzalez MS, Tye GW. Sonographic localization of a nonpalpable shunt: Ultrasound-assisted ventricular shunt tap. Surg Neurol Int 06-Aug-2013;4:101. Available from: http://sni.wpengine.com/surgicalint_articles/sonographic-localization-of-a-nonpalpable-shunt-ultrasound-assisted-ventricular-shunt-tap/
Background:Patients frequently present to the emergency department (ED) for evaluation of cerebrospinal fluid (CSF) shunt malfunction, often requiring urgent management. A typical evaluation in the emergency room setting includes a thorough history and physical examination, noncontrasted head computed tomography (CT), shunt series, and occasionally a ventricular shunt tap.
Case Description:We present the case of a 53-year-old male who initially presented to the ED in acute status epilepticus. His history was notable for seizures and multiple craniectomies and cranioplasties with subsequent placement of a ventriculoperitoneal shunt secondary to traumatic brain injury. Imaging in the ED suggested possible shunt failure. No previous imaging was available for comparison, and therefore a ventricular shunt tap was attempted. Initially, the tap could not be performed, as the shunt was not palpable secondary to the thickness of his scalp and location of the reservoir near his complex cranial reconstruction site. We report, for the first time, the utility of emergency ultrasound (EUS) to aid in such an encounter.
Conclusion:EUS revealed the exact location of his shunt reservoir, and therefore enabled the shunt tap, which ultimately led to the discovery of the patient's proximal shunt failure in a setting that may have otherwise been missed. The patient underwent urgent shunt revision with a good outcome.
Keywords: Hydrocephalus, shunt failure, ultrasound guidance, ventricular shunt tap
Patients frequently present to the emergency department (ED) for evaluation of cerebrospinal fluid (CSF) shunt malfunction, possible causes of which include disconnection, calcification, and migration of the shunt from its intended position and blockage.[
A 53-year-old male with a past medical history significant for hypertension, noninsulin-dependent diabetes mellitus, alcohol abuse, seizures, and traumatic brain injury secondary to a fall, necessitating several decompressive craniectomies, bilateral cranioplasties and a left occipital ventriculoperitoneal (VP) shunt (Rickham reservoir), initially presented to an outside institution obtunded and in acute status epilepticus. Seizures were initially generalized tonic-clonic, and then later right-sided convulsions with eye deviation. His seizures were aborted with intravenous lorazepam and fosphenytoin. A head CT was obtained at that time that was suggestive of hydrocephalus, which prompted transfer to our facility.
Upon arrival to our ED the patient was noted to have residual focal right arm and facial twitching, for which he was reloaded with antiepileptic agents. The patient was new to our institution, and no prior imaging was available to aid in determining if he had acute hydrocephalus. A shunt series obtained in the ED showed no signs of discontinuity throughout the shunt system. Therefore, we attempted to perform a VP shunt tap to assess intracranial pressure and determine if he had either proximal or distal shunt failure. Initially, on examination his shunt reservoir was not palpable. This was likely secondary to the large thickness of his scalp and the location of his Rickham reservoir near a burr hole cover and along a raised ridge from his left cranioplasty site [
Axial sections from a noncontrast enhanced computed tomographic images of the head (bone window). The complexity of the bilateral cranioplasties can be appreciated in these images. The left occipital Rickham reservoir is located medial to the burr hole cover and ridge from the left cranioplasty
We utilized the ED's portable ultrasound machine (Edge ® model; SonoSite, Incorporated), typically used in the ED for other procedures, to quickly assist us with imaging through the scalp. Using a 6 cm, 13-6 MHz linear transducer, visualization in both the short-axis and long-axis views allowed for a thorough examination and confirmation of the exact placement of the Rickham reservoir [
Shunting of the ventricular system for diversion of CSF fluid in patients with hydrocephalus remains the most prominent and accepted treatment of choice.[
Patients frequently present to the ED for evaluation of ventricular shunt malfunction; symptoms most often include headaches, lethargy, nausea, vomiting, irritability, and fever.[
A diagnostic modality that has long been available is the ventricular shunt tap. Although not always utilized, this minimally invasive technique has the ability to measure an opening intracranial pressure and assess proximal and distal catheter function.[
Invasive procedures are frequently performed in the ED. In recent years emergency ultrasonography has become a valuable tool, allowing procedures once guided by physical exam and surface anatomy to be done under ultrasound guidance (dynamic guidance) or ultrasound assistance (static guidance).[
The literature continues to be sparse with respect to sonographic evaluation of VP shunts. Previous reports describe the use of Doppler ultrasound to both directly and indirectly evaluate VP shunt function by looking at flow patterns in areas of turbulence.[
We describe a technique in which the application of EUS enabled our team to determine the precise location of a shunt reservoir in a patient with a complex cranioplasty presenting with signs concerning for shunt malfunction. This simple and fast approach allowed for the accurate guidance of a ventricular shunt tap, in a setting where it may have otherwise been too difficult and consequently missed. Using ultrasound to visualize the site of a ventricular shunt reservoir in real-time has numerous clinical applications, which includes obtaining CSF fluid for analysis of cytology or infection, evaluation of shunt function, the injection of intrathecal medication (antibiotics or chemotherapeutic agents), and as a therapeutic temporizing measure to allow for function of a distally occluded shunt.
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