Technique

A Modified Technique To Treat
Chronic and Subacute Subdural
Hematoma: Technical Note
Wilson T. Asfora, MD, FRCSC,* and Lisa Schwebach, BSc, MD†
*Section of Neurosurgery, University of South Dakota School of Medicine, Sioux Falls,
South Dakota, and †Creighton University School of Medicine, Omaha, Nebraska

Asfora WT, Schwebach L. A modified technique to treat chronic
and subacute subdural hematoma: technical note. Surg Neurol
2003;59:329 –32.
BACKGROUND

We present a patient on warfarin in whom a drainage port
system was attached to the skull, successfully draining a
subacute subdural hematoma.
CASE DESCRIPTION

An elderly male presented to our institution with right
hemiparesis a week following a motor vehicle accident.
He was on warfarin for recurrent pulmonary emboli and
suffered from severe coronary artery disease. Physical
examination demonstrated a grade 3/5 hemiparesis and a
computerized tomography (CT) scan confirmed the diagnosis of subacute subdural hematoma. He underwent
twist drill craniostomy and attachment of the subdural
evacuating port system. Recovery in this patient was
dramatic.
CONCLUSION

The subdural evacuating port system (SEPS) permits the
neurosurgeon to drain subacute or chronic hematomas by
a method that is minimally invasive, simple, and safe. The
SEPS appears to promote brain expansion without the potential biohazards of other standard techniques. © 2003
Elsevier Inc. All rights reserved.
KEY WORDS

Subdural hematoma, true closed system drainage, twist drill
craniostomy.

here exist numerous methods for the surgical
treatment of chronic and subacute subdural
hematomas [1,2,6,7,9,10]. These include burr hole
irrigation with or without subdural catheter placement, twist drill catheter insertion, and craniotomy.

T

Disclosure: The SEPS was developed with the assistance of Medical
Designs, LLC, Brandon, South Dakota. Dr Asfora has a licensing agreement
with Medical Designs, LLC, for the device described in this paper. US
Design Patent Number D435,291 covers the Subdural Evacuating
Port device.
Address reprint requests to: Dr Wilson T. Asfora, Sioux Falls Neurosurgical Associates, North Center, 1210 W. 18th Street, Suite 104, Sioux Falls,
SD 57104-4650.
Received June 8, 2001; accepted November 26, 2002.
© 2003 Elsevier Inc. All rights reserved.
360 Park Avenue South, New York, NY 10010 –1710

Steroids are occasionally used. All are acceptable;
their use is a matter of personal preference. The
variety of surgical strategies, however, is testimony
to their frequent failure and potential for complications. Burr hole irrigation often allows entrainment
of air into the subdural space. Pneumocephalus,
even in the absence of tension, increases morbidity
and headache. A variety of catheters have been
inserted into the subdural space, either through
burr holes or twist drill holes. These may impale
brain parenchyma or injure tenuous bridging veins.
Application of suction to a catheter in the subdural
space may result in brain or meninges plugging its
perforations. Larger catheters may provoke seizures when abutting cortex. They may act as bacterial conduits, increasing the risk of subdural empyema. In our method, a hollow screw (port) is
threaded to the skull through a twist drill opening,
not entering the subdural space. The port is then
connected to a Jackson-Pratt-type suction reservoir, thereby establishing a true closed drainage
system that is established to evacuate the subacute
and chronic subdural hematomas. Although this is
similar to an existing system, there are significant
design differences [4]. Our system introduces a
mild, uniform, negative pressure throughout the
subdural space, thus promoting slow drainage of
the fluid collection and the gradual decompression,
re-expansion, and recovery of the brain.

Device Description and
Insertion Technique
The subdural evacuating port system (SEPS) consists of a stainless steel evacuating port (Figure 1),
stainless steel drill bit with safety stop collar, set
screw and Allen wrench, silicone tubing, a silicone
suction reservoir bulb, and flexible ruler. The evac0090-3019/03/$–see front matter
doi:10.1016/S0090-3019(03)00039-9

330 Surg Neurol
2003;59:329 –32

1

Asfora and Schwebach

Subdural evacuating port.

uating port is a 6 mm outside diameter tube, 4.5 cm
in length with a pair of wings extending from the
exterior surface to facilitate manual insertion. The
evacuating port has self-tapping threads on the
proximal end and a series of annular barbs on the
distal end. The 5.8 mm drill bit is used to create a
twist drill hole through the outer and inner tables of
the patient’s skull. After opening the dura with an
electrocoagulator, the evacuating port is threaded
into the opening of the skull with a clockwise twisting motion. One end of the silicone tubing is attached to the suction reservoir bulb. A low negative
pressure (ⱕ2.5 cm Hg) is applied by gently squeezing the reservoir bulb, and this, in turn, allows for
external drainage of subdural fluid and the gradual
decompression, re-expansion, and recovery of the
brain.

Case Report
A 69-year-old male was referred to our facility with
a history of progressive weakness and a decreasing
level of consciousness. He had been involved in a
motor vehicle accident approximately one week
prior. He was taking warfarin, 10 mg daily, for recurrent pulmonary emboli and suffered from
chronic coronary artery disease. Physical examina-

tion revealed drowsiness, inability to obey commands, and global dysphasia. Cranial nerve function was normal and there was grade 3/5
hemiparesis of the right arm and leg. Laboratory
tests confirmed coagulopathy and two units of fresh
frozen plasma were administered. The CT scan
showed a large, subacute subdural on the left with
18 mm of shift. (Figure 2A). The patient was taken to
the operating room that day and had a left frontal
twist drill craniostomy performed under local anesthesia. The dura was opened, the port screwed into
the skull, and the closed suction drainage system
established. Surgical time was rapid, approximately
5 minutes. Postprocedure the patient’s level of consciousness and hemiparesis improved rapidly. The
port system was removed within 48 hours from
initial procedure with the wound being closed with
a single stitch. Follow-up examination and CT scan
2 months later were within normal limits (Figure
2B).

Discussion
Unlike other comparable devices [8,9], the SEPS
does not enter the intracranial space. The proximal
tip of the evacuating port remains within the bone,
similar to the Camino bolt (Integra NeuroCare, San

Chronic Subdural Hematomas and SEPS

(A) Preoperative CT of patient with subacute subdural hematoma. (B) Postoperative CT of same
patient.

2

Diego, CA) used for intracranial pressure monitoring. The inner diameter of our port is 5 mm, in
contrast with the 2.3 mm of the screw described by

Surg Neurol 331
2003;59:329 –32

Emonds et al [4]. They report this to be a disadvantage and do not recommend its use for large blood
clots. Drainage catheter-type devices that are in
direct contact with the brain or well-vascularized
outer membranes may be associated with more
subdural rebleeding than devices that are not in
direct contact with the brain, bridging veins, or
subdural membranes, particularly if negative pressure is applied. Adhesions can also form between
these catheters and the subdural membranes if left
in place for prolonged periods. Our SEPS technique
also differs from other drainage procedures in that
the subdural space is not irrigated during or after
the procedure, which significantly reduces operating room time. Irrigation has not been shown to
improve outcomes [8]. There are no leaks around
the subdural port or its bulb and tubing. This reduces the risk for infection and maintains a fairly
constant negative pressure in the closed drainage
system. The fluid drainage may be continuous or
intermittent and is gradual and independent of
gravity. It is therefore not necessary to keep patients flat in bed for extended periods of time. Patients are allowed to increase activity as tolerated,
typically beginning on the first day following the
SEPS surgery. Additionally, to maximize effectiveness, the port should be positioned over the point
at which the subdural collection is at its greatest
thickness; otherwise loculation may occur. If on
preoperative CT or magnetic resonance imaging
(MRI) the hematoma is noted to be loculated, the
use of additional ports may be considered. The
SEPS should remain in place until the hematoma
stops draining, generally 24 to 48 hours. If the patient has not improved neurologically and the initial
postoperative CT scan shows significant mass effect, alternative treatments (craniotomy, burr hole,
etc.) should be considered if the patient has stabilized medically.
To date we have treated 32 patients who presented with chronic, subacute, and acute-onchronic subdural hematoma by means of one or
multiple subdural evacuating ports. Follow-up has
ranged from one to 24 months. In 26 patients
(81.2%) the postoperative course was uneventful
with complete evacuation of the hematomas, resolution of symptoms, and no adverse sequelae reported by either the patient or his/her referring
physicians. A follow-up CT carried out the day following the procedure revealed significant residual
subdural hematoma with mass effect in three patients. Needle aspiration of residual hematoma
through the SEPS to unplug the port was successfully carried out in two of these patients without
further recurrence of the hematoma. The third pa-

332 Surg Neurol
2003;59:329 –32

Asfora and Schwebach

tient was taken to surgery for a craniotomy that
revealed multiple layers of subdural membranes;
the SEPS was patent. In another three patients
(9.4%), recurrence of the hematoma was noted
within 1 to 2 months. Of these three patients (9.4%),
one was treated by percutaneous aspiration of the
recurrent hematoma through the previous twist
drill hole site, while the other two patients, in view
of an acute subdural hematoma component, were
treated by standard craniotomy.
In our experience, we feel that the SEPS is a viable
alternative in treating patients with chronic, subacute, and acute-on-chronic subdural hematoma,
especially it they are fully anticoagulated, or in
whom general anesthesia is contraindicated because of an unstable medical situation. It has also
worked as a temporary measure in a more acute
setting in an attempt to decrease intracranial pressure until the patient can undergo standard
craniotomy.

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The relationship between brain surface elastance and
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6. Hamilton MG, Frizzell JB, Tranmer BI. Chronic subdural hematoma: the role of craniotomy re-evaluated.
Neurosurgery 1993;33(1):67–72.
7. Hubschmann Otakar R. Twist drill craniostomy in the
treatment of chronic and subacute hematomas in severely ill and elderly patients. Neurosurgery 1980;
6(3):233–6.
8. Suzuki K, Sugita K, Akai T, Takahata T, Sonobe M,
Takahashi S. Treatment of chronic subdural hematoma by closed system drainage without irrigation.
Surg Neurol 1998;50:231–4.
9. Tabaddor K, Shulmon K. Definitive treatment of
chronic subdural hematoma by twist-drill craniostomy and closed system drainage. J Neurosurg 1977;
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10. Weir BKA. Results of burr hole and open and closed
suction drainage for chronic subdural hematomas in
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REFERENCES

COMMENTARY

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The authors have presented a modified extracranial
bolt method for drainage of chronic subdural hematomas. This technique appears to have benefits
over conventional burr hole drainage with or without irrigation in patients at increased risk for bleeding or pneumocephalus.
Jeffrey E. Pearce, M.D.
Neurosurgeon
Bellevue, Washington

n honest man is not the worse because a dog barks at him.

A

—Danish Proverb