Keywords
deep brain stimulation - electrode lead - infection - intractable wound - cutaneous
fistula - intrawound continuous negative pressure and irrigation therapy - reconstruction
- pericranial flap - scalp flap
Introduction
Deep brain stimulation (DBS) therapy involves electrical stimulation of the subthalamic
nucleus and the globus pallidus, and it is widely used for Parkinson's disease.[1]
[2] However, wound infection and dehiscence may occur in rare cases, and such infection
can be very difficult to treat, with removal of the electrode leads being necessary.[3]
[4] In 2006, we reported the usefulness of a pericranial flap for reconstruction of
the dura mater.[5] In 2007, intrawound continuous negative pressure and irrigation treatment (IW-CONPIT)
was reported,[6] after which this method has been applied to treat infected and/or intractable wounds
at various sites. In 2016, the efficacy of IW-CONPIT using a closed system was reported
for controlling infection of all layers of the cranium combined with cerebrospinal
fluid leakage.[7] We applied these methods (pericranial flap reconstruction and IW-CONPIT) in two
patients with wound infection after implantation of DBS systems (Medtronic Inc., Minneapolis,
Minnesota, United States), allowing infection to be managed without removal of the
electrode leads so that DBS therapy could subsequently be continued ([Table 1]).
Table 1
Summary of patient characteristics and surgical interventions
|
Patient no.
|
Age (y/Sex)
|
Time to fistula, (mo)
|
Infectious agent
|
Primary intervention
|
Secondary intervention
|
Duration of continuous irrigation and negative pressure
|
Follow-up
|
|
1
|
61/F
|
6
|
MRSA
|
Scalp undermining and pericranial flap
|
None
|
7 d
|
18 mo, no recurrence
|
|
2
|
67/F
|
4
|
MRSA
|
Bi-pedicled scalp flap, right-thigh split-thickness skin graft
|
None
|
7 d
|
19 mo, no recurrence
|
Abbreviation: MRSA, methicillin-resistant Staphylococcus aureus.
Case 1
History and Presentation
A 61-year-old woman developed a cutaneous fistula at 6 months after surgery for placement
of DBS electrodes to treat Parkinson's disease at the Neurosurgery Department of another
hospital. The patient was referred to our department because the fistula persisted.
At initial examination, a cutaneous fistula was seen in a scar on the forehead. Drainage
of pus was observed, and a silicon cap for fixing the electrode was visible inside
the fistula ([Fig. 1A–F]).
Fig. 1 Patient 1: photographs and diagram. (A) Preoperative photograph in the frontal view. Cutaneous fistula (white arrow) on the forehead draining pus. (B) Preoperative photograph in the lateral view. White arrowheads: track of the electrode
lead under the skin. (C) Preoperative anteroposterior X-ray film showing the temporal and parietal electrode
leads. (D) Preoperative noncontrast head computed tomography (CT) showing the temporal and parietal
electrode leads. (E) Preoperative bone image CT showing the silicon cap and the burr hole. (F) Diagram of the fistula. A silicon cap for fixing the electrode lead was located just
under the fistula: (a) Cutaneous fistula; (b) Scalp; (c) Bone; (d) Electrode lead;
(e) Dura mater; (f) Infected granulation tissue; (g) Cap for fixing the electrode
lead; (h) Bone to be removed during debridement (shaded area). (G) Intraoperative view of the DBS electrode lead fixed with a titanium miniplate and
two 3-mm screws. Debridement was conducted without removing the electrode lead. To
prevent scar contracture and hair loss, a zigzag incision was made in the scalp to
raise the pericranial flap. Arrow: lead entering the burr hole in the cranium. (H) Diagram after debridement of granulation tissue and smoothing of the rim of the bone
defect: (a) Cutaneous fistula; (b) Scalp; (c) Bone; (d) Electrode lead; (e) Dura mater.
(I) Design of the pericranial flap with a pedicle on the parietal side. White arrowheads:
incision line for the flap. Black dashed circle: bone to be removed around the fistula.
(J) Elevated pericranial flap. Asterisk (*): body of the flap. (K) Covering the fistula site, electrode lead, and bone with the pericranial flap. Asterisk
(*): pericranial flap transposed over the bone defect and electrode lead. (L) Appearance at the end of surgery. Initiation of intrawound continuous negative pressure
and irrigation therapy. Black arrow: irrigation tube. Dashed white arrows: suction
tube. Black arrowhead: fistula left open without suturing. (M) Diagram at completion of surgery with intrawound continuous negative pressure and
irrigation therapy: (a) Cutaneous fistula; (b) Scalp; (c) Bone; (d) Electrode lead;
(e) Dura mater; (f) Transplanted pericranial flap; (g) Irrigation tube; (h) Suction
tube. Dashed red arrow: direction of saline flow. (N) Postoperative photograph in the frontal view. There is no depression at the flap
donor site. (O) Postoperative photograph in the lateral view. No recurrence of infection or the fistula.
Black arrowhead: completely epithelialized cutaneous fistula. (P) Postoperative anteroposterior X-ray film showing no migration or retraction of the
leads. (Q) Postoperative noncontrast CT showing no intracranial hemorrhage. (R) Postoperative bone image CT showing no dead space at the fistula site.
Operation
After re-opening the wound via the previous incision line, infected granulation tissue
was detected around the silicon cap and along the electrode line. The silicon cap
was removed, but the electrode lead was left in situ to continue DBS therapy for Parkinson's
disease ([Fig. 1G]). Debridement of the infected granulation tissue was performed and the edges of
the bone defect left after component removal were smoothed ([Fig. 1H]). A pedicled pericranial frontalis muscle flap was harvested from the parietal region
on the healthy (right) side, and was used to cover the electrode lead and fill the
dead space in the bone defect ([Fig. 1I–K]). The edges of the debrided fistula showed very poor circulation. Because the pericranial
flap was placed under the fistula, there was no bone exposure; hence, healing by secondary
intention was deemed possible and the fistula was left open without suturing ([Fig. 1L]). To prevent postoperative infection, two drains were placed between the pericranial
flap and the bone, and closed IW-CONPIT was initiated with saline at 2,000 mL/d ([Fig. 1L,M]).[6] After conducting IW-CONPIT for 1 week, the drains were removed since there were
no signs of infection.
Postoperative Course
The postoperative course was good and the fistula showed epithelialization by 2 weeks
after surgery. There has been no relapse of the fistula or infection during follow-up
for 1.5 years. In addition, a depression has not developed at the previous site of
the fistula or at the frontalis muscle donor site, with the cosmetic outcome being
satisfactory ([Fig. 1N–R]). It was also possible to continue DBS therapy for Parkinson's disease.
Case 2
History and Presentation
A 67-year-old woman with Parkinson's disease developed wound dehiscence at 4 months
after surgery for implantation of DBS electrodes at another hospital. At initial examination,
drainage of pus from a cutaneous fistula and exposure of a silicon cap were observed
([Fig. 2A–C]).
Fig. 2 Patient 2: Preoperative photographs and preoperative computed tomography (CT). (A) Preoperative photograph in the frontal view. Two cutaneous fistulae can be seen over
the frontal lobe. A silicon cap for fixing the electrode lead was present under the
fistula. Black arrows: cutaneous fistulae. (B) Lateral X-ray film showing the parietal electrode leads. (C) Preoperative noncontrast head CT showing the parietal electrode leads and the dead
space around the silicon cap. (D) Preoperative photograph from above showing the incision line for debridement around
the fistula. (E) Design of the bi-pedicled scalp flap. Black asterisk (*): body of the scalp flap.
Black arrowheads: incision line for the scalp flap. (F) After transferring the bi-pedicled scalp flap. Black arrow: direction of flap movement.
†: pericranium; periosteum, and loose connective tissue exposed after flap transfer.
(G) Diagram of the fistula site: (a) Cutaneous fistula; (b) Scalp; (c) Electrode lead;
(d) Bone; (e) Dura mater; (f) Bone to be removed during debridement (red shaded area); (g) Bi-pedicled scalp flap. Black arrow: direction of flap movement. Red line:
incision line for the flap; (h) Pericranium exposed by flap transfer. (H) Photograph at the end of surgery. The bi-pedicled scalp flap has been used to cover
the fistula, electrode lead, and bone. Solid arrow: irrigation tube. Dotted arrow:
suction tube. Asterisk (*): split skin graft on the pericranium. (I) Diagram at completion of surgery with intrawound continuous negative pressure and
irrigation therapy: (a) Transplanted bi-pedicled flap covering the cutaneous fistulae;
(b) Scalp; (c) Electrode; (d) Bone; (e) Dura mater; (f) Irrigation tube; (g) Suction
tube. Dashed red arrow: direction of saline flow; (h) Pericranium at the flap harvest
site; (i) Split skin graft. (J) Photograph at 7 months after surgery. There is no recurrence of the fistulae or infection.
Black arrowhead: site where the fistulae previously existed. (K) Postoperative lateral X-ray film showing no migration or retraction of the leads.
(L) Postoperative CT showing no intracranial hemorrhage and no dead space at the fistula
site.
Operation
A fusiform skin incision was made to resect the cutaneous fistula, revealing that
the old surgical wound was filled with infected granulation tissue ([Fig. 2D]). As was done for Case 1, the cap was removed while retaining the electrode lead.
Debridement of infected granulation tissue was performed and the edges of the bone
defect were smoothed. Then the wound was closed by using a bi-pedicled flap raised
from the right side ([Fig. 2E–G]), while the donor site was covered with a skin graft. Closed IW-CONPIT was initiated
immediately after surgery ([Fig. 2H,I]) and was continued for 1 week, following which the drains were removed because there
were no signs of infection.
Postoperative Course
At 1 year and 7 months after wound healing, there has been no recurrence of the fistula
or infection ([Fig. 2J–L]). In addition, DBS therapy has been continued for Parkinson's disease.
Discussion
Parkinson's disease is caused by degeneration of dopaminergic cells in the substantia
nigra of the midbrain, with the consequent lack of dopaminergic stimulation causing
motor symptoms such as tremor, muscle rigidity, and akinesia. Anticholinergics and
levodopa preparations are used as standard medical treatment, but control of symptoms
such as wearing-off and dyskinesia is problematic. DBS therapy was reported by Benabid
et al in 1987,[1] and it is a treatment for various neurological diseases that involves electrical
stimulation of the globus pallidus, thalamus, or subthalamic nucleus via implanted
electrodes. In patients with Parkinson's disease, DBS therapy can be effective for
akinesia and rigidity, as well as for wearing-off symptoms, and it is currently the
mainstream surgical treatment for this disease.[2] However, the risk of infection and exposure always exists when devices are implanted
surgically. In principle, infections that do not respond to conservative treatment
require removal of the implanted device,[3]
[4] making it impossible to continue DBS therapy.
We encountered three problems when managing the patients presented here. First, wound
healing was prevented by the presence of the implanted devices and infected granulation
tissue. Second, there was a risk of creating dead space under the scalp if the wound
was simply closed after debridement of granulation tissue. Third, it was important
to retain the electrode leads for future performance of DBS, despite the intractable
wound infection.
These three problems were managed as follows: First, the nonessential parts of the
DBS system were removed and thorough debridement was performed. Second, the edges
of the bone defect were smoothed to promote adherence of the skin flap. Then we covered
the electrode lead by using a local flap such as a pericranial flap or bi-pedicled
scalp flap with good blood supply.[8] Flaps such as galeal, temporalis fascial, or pericranial flaps are reliable, thin,
and supple, as well as having a good arc of rotation and minimal donor site morbidity.[9] These flaps can also be raised in the vicinity of the operative field, which is
convenient for the neurosurgeon.[10] In Case 1, we used a thin and flexible pericranial flap to fill the dead space while
covering the electrode lead. In Case 2, a bi-pedicled flap with good mobility was
transferred freely to broadly cover the bone defect without suturing under tension.
Finally, postoperative closed IW-CONPIT was performed with a high volume of saline
for infection control.[6] In 1997, vacuum-assisted closure was reported as an effective method for increasing
granulation tissue formation in subacute and chronic wounds.[11] However, this method has no suppressive effect on wound infection. On the other
hand, IW-CONPIT is designed for infected wounds and can be used to treat intractable
wound infection at various sites.[12]
[13] The key points of IW-CONPIT are reducing bacteria in the wound by continuous irrigation
for 24 hours per day and elimination of dead space by negative pressure. IW-CONPIT
can be supplemented by flap transplantation. In our patients, adhesion between a local
flap with a good blood supply and the tissues around the fistula was promoted by maintenance
of negative pressure using IW-CONPIT, resulting in control of wound infection.
If infection occurs following implantation of a DBS device, taking these measures
can make it possible to eliminate wound infection while retaining the electrode lead
in situ, allowing DBS therapy to be continued.
