American Journal of Neuroradiology 27:74-75, January 2006
© 2006 American Society of Neuroradiology
TECHNICAL NOTE
BRAIN
Imaging Characteristics of the Subdural Evacuating Port System, a New Bedside Therapy for Subacute/Chronic Subdural Hematoma
S.S. Lollis,
M.L. Wolak and
A.C. Mamourian
Section of Neurosurgery, Dartmouth-Hitchcock Medical Center, Lebanon, NH
Section of Neuroradiology, Dartmouth-Hitchcock Medical Center, Lebanon, NH
Address correspondence to: Alexander C. Mamourian, Section of Neuroradiology, Dartmouth-Hitchcock Medical Center, Lebanon, NH 03756
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Abstract
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SUMMARY: The Subdural Evacuating Port System is a new device
intended to simplify the treatment of subacute/chronic subdural
hematomas. The appearance of the winged canula positioned with
its tip in the diploic space overlying the subdural space should
allow the radiologist to identify it correctly. Its radiographic
features are described here to help the radiologist comment
on appropriate placement, and avoid mistaking it for a misplaced
subdural drain.
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Introduction
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The Subdural Evacuating Port System (SEPS) is a new therapy
(Medical Designs, LLC, Sioux Falls, SD) designed to treat subacute
or chronic subdural hematomas.
1,
2 It can be placed at the bedside
and permits drainage of fluid during a period of hours to days.
The purpose of this report is to describe the imaging characteristics
of this device.
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Case Report
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An 81-year-old man presented to our facility with 4 weeks of
progressive gait instability and poor coordination of the left
upper extremity. These symptoms began shortly after he fell
on an icy pavement, striking his right parieto-occipital region.
A head CT scan revealed a right convexity subdural hematoma
with mass effect on the adjacent brain. The neurosurgical service
was consulted, and they decide to treat the patient with the
SEPS.
Description of the Device
The SEPS consists of a stainless steel evacuating port, radiolucent silicone tubing, and a bulb suction device. It can be placed at the bedside by using a technique similar to that employed for the placement of a subarachnoid bolt used for intracranial pressure monitoring. After localizing the subdural collection by using superficial landmarks and making an appropriate skin incision, the surgeon places a single burr hole in the calvarium using a manual drill with a 5.8-mm drill bit. The dura is then opened and the metal evacuating port is manually screwed into the hole in the skull so that the tip is positioned in the diploic space, not extending beyond the inner table. The external portion of the evacuating port is then connected to the silicone tubing and bulb suction apparatus. Negative pressure (
2.5 cmHg) is applied by using a bulb for a variable time period, typically 24–48 hours, but until drainage of subdural fluid has ceased. The system is then removed and the skin sutured is closed.
Imaging Characteristics
The SEPS can be distinguished radiographically from a typical, bolt-type intracranial pressure monitor. First, the SEPS evacuating port is larger, measuring 4.5 cm in length and 6 mm in tip width (Fig 1). It has metal wings, giving it the appearance of a cross on reformatted images (Fig 2). Second, the evacuating port consists entirely of stainless steel; typical intracranial pressure monitors consist of a metal central core, with radiolucent wings to assist in placement. The SEPS is also easily distinguished from subdural catheters. The evacuating port is anchored into the diploic space and represents the most medial end of the device (Figs 3 and 4)—ie, there is no subdural catheter extending along the surface of the brain.
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Fig 1. A, This image shows the metal device that is screwed into the burr hole. The threaded end (black arrow) is self-tapping. The notched tubing (white arrow) is then attached to the silicone tubing.
B, This reformat of the CT data shows the metal insertion portion of the device orientation perpendicular to the skull.
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Fig 2. Oblique (A) and A-P (B) views, reformatted from CT data on a 3D workstation (Vitrea), demonstrate the winged canula and its relationship to the skull.
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Fig 3. The bone image from that same study shows the tip of the device positioned in the diploic space of the right calvaria (arrow).
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Fig 4. The reformatted 2D image demonstrates the relationships of the subdural hematoma (short arrows) and the device positioned in the skull (long arrow).
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Discussion
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Although several surgical options exist for treatment of subacute
and chronic subdural hematomas, recent studies suggest that
optimal management involves twist-drill catheter placement and
drainage via a closed external drainage system.
3 This procedure
can be performed either in the operative theater or at the bedside.
The drainage system typically consists of a radiopaque catheter
placed in the subdural compartment, which is connected to a
Jackson-Pratt-type suction reservoir via a radiolucent connector
tube. The SEPS is a new approach to treatment of subdural hematomas.
The decision to use the SEPS may be based on several potential
advantages over twist-drill catheter placement and drainage.
The SEPS introduces mild, uniform negative pressure throughout
the subdural space without direct contact with the brain, cortical
or bridging vessels, or vascularized hematoma membranes. The
risk of catheter-related parenchymal injury and iatrogenic hemorrhage
are theoretically reduced. It is likely that radiologists practicing
at neurosurgical centers will see an increasing number of CT
scans after placement of this system. The system has unique
imaging characteristics that distinguish it from bolt-type intracranial
pressure monitors, as well as subdural catheters. It is important
to be able to recognize the SEPS and comment on its appropriate
placement.
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References
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- Asfora WT, Schwebach L. A modified technique to treat chronic and subacute subdural hematoma: techincal note. Surg Neurol 2003;59:329–32[Medline]
- Asfora WT, Schwebach L, Louw D. A modified technique to treat subdural hematomas: the Subdural Evacuating Port System. S D J Med 2001;54:495–98[Medline]
- Williams GR, Baskaya MK, Menendez J, et al. Burr-hole versus twist drill drainage for the evacuation of chronic subdural hematoma: a comparison of clinical results. J Clin Neurosci 2001;8:551–54[Medline]
Received June 7, 2005;
accepted after revision July 20, 2005.
TOP
Abstract
Introduction