Results The current ‘ban’on monopolar use appears to be
extrapolated from the use of medical diathermy, a very differ-
ent modality. At no point did the implant site temperature
rise more than 2.4°C. Microscopic analysis post procedure
revealed no thermal damage.
Conclusions Electrocautery in the context of DBS is safer than
P35 ABILITY TO QUANTIFY
ELECTRODE TRAJECTORY PROXIMITY TO VESSELS
ACROSS IMAGING PROTOCOLS
Wellcome/EPSRC Centre for Interventional and Surgical Sciences (WEISS),
University College London, London, UK;
Department of Clinical and Experimental Epilepsy,
University College London, London, UK and National Hospital for Neurology and
Neurosurgery, Queen Square, London, UK;
Wellcome/EPSRC Centre for Interventional and
Surgical Sciences (WEISS), University College London, London, UK and Department of
Clinical and Experimental Epilepsy, University College London, London, UK;
Biomedical Engineering and Imaging Sciences, St Thomas’Hospital, King’s College London,
Objectives Automated planning of stereoelectroencephalography
(SEEG) electrode trajectories is dependent on vessel segmenta-
We quantify imaging protocols ability to measure trajec-
Design Retrospective analysis.
Subjects Ten consecutive patients were selected whom had
SEEG implantation (95 electrodes) and Digital Catheter Sub-
traction Angiography (DSA) with catheterization of carotid or
vertebral arteries, post-gadolinium T1-weighted (GAD), phase-
contrast MR angiography and MR venography (MR) acquired.
Methods SEEG trajectories were planned manually with DSA.
Minimum distance to vessels and risk
were computed for
each trajectory using vessel segmentation from GAD, MR, or
DSA. Vessel size was considered by including DSA vessels
diameters above 1, 2, 3, or 4 mm.
Results Minimum distance to a vessel was 6.2±3.9 mm
(GAD), 2.5±1.6 mm (MR), and 1.5±1.2 mm (DSA). Based on
DSA vessel size minimum distances were 2.0±1.5 mm
(DSA >1 mm), 3.4±2.6 (DSA >2 mm), 6.6±4.6 mm
(DSA >3 mm), and 11.8±7.9 mm (DSA >4 mm). Risk was
0.4±0.4 (GAD), 0.8±0.4 (MR), and 1.1±0.2 (all DSA), 1.0
±0.2 (DSA >1 mm), 0.7±0.4 (DSA >2 mm), 0.4±0.5
(DSA >3 mm), and 0.2±0.3 (DSA >4 mm).
Conclusions DSA is best able to segment vessels. MR has met-
rics similar to DSA vessels above 2 mm. GAD has metrics sim-
ilar to DSA vessels above 3 mm.
P36 A 1 AND 5 YEAR OUTCOME ANALYSIS OF EPILEPSY
SURGERY IN ADULTS AND CHILDREN
Salford Royal Foundation Trust, Salford, UK;
Royal Manchester Children’s Hospital, Manchester, UK
Objectives To evaluate the efficacy of epilepsy surgery at
1 year following surgery and to assess sustainability of seizure
control at 5 years post-surgery. To find prognostic factors for
good surgical outcomes.
Design Retrospective case notes analysis.
Subjects 82 consecutive patients operated on for epilepsy by a
single surgeon between 2008–2013.
Methods Patients were identified in pre-existing hospital data-
bases and included if 5 year follow-up was available. Their
clinical records were accessed via the electronic patient records
system at each site. The Engel Classification was used to grade
seizure outcome at years 1 and 5 post-surgery. We classified
Engel Class I and II as a good outcome and Engel class III
and IV as a poor outcome. Case notes were also examined to
find prognostic factors for a good long-term surgical outcome.
Results 86.4% of patients had a good outcome 1 year post-
surgery and 77.9% had a good outcome at 5 years. The sur-
gery site (temporal or otherwise) and the presence of a good
outcome at year one were found to contribute significantly to
odds of a good outcome at year 5. The ability to wean off
medication is also commonly an important factor for patients
and 24.4% of patients were AED free at 5 years.
Conclusions Surgery is an effective management option for
intractable epilepsy in suitably selected patients with complete
or near complete seizure cessation in about 80% of the
patients and about a quarter of the patients no longer requir-
P37 DO ALL NOTOCHORDAL LESIONS REQUIRE PROTON
BEAM RADIOTHERAPY? A CASE SERIES OF
King’s College Hospital, London, UK;
University of Manchester, Manchester,
Objectives Ecchordosis physaliphora (EP) is a benign, usually
asymptomatic, notochord tumour but may also present with a
spontaneous CSF fistula. Differentiating EP from its more
aggressive counterpart, chordoma is challenging but important
as the clinical course and management differ significantly, with
the latter requiring proton beam radiotherapy. This case series
aims to further inform this discussion.
Design Case series.
Subjects Patients with suspected EP from 2015–2018.
Methods Retrospective analysis.
Results Six patients were identified. Four presented with sus-
pected CSF leak. MRI revealed a T1-hypointense and T2-
hyperintense clival lesion without enhancement. CT showed
pneumocephalus, a clival defect and no mass lesion. All under-
went endoscopic endonasal repair of CSF fistula with biopsy.
Histology revealed physaliphorous cells with no mitoses;
immunohistochemistry confirmed notochord origin (EMA,
S100, CD10 and/or MNF116) and low proliferation index. In
2 patients, EP was found incidentally on imaging and these
lesions have remained static on follow-up.
Conclusions In the absence of a clival mass, notochord rem-
nant lesions with benign histopathology can be treated as EP
and patients can avoid radiotherapy. The diagnosis of EP,
however, remains challenging as no distinctive histopathologi-
cal marker exists to differentiate it from chordoma and until
a genetic or immunohistochemical marker is identified, the
diagnosis rests solely on the presence or absence of a mass on
e34 J Neurol Neurosurg Psychiatry 2019;90(3):e1–e53
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