Page 48 - NNS 2014 Program & Abstract Book

locomotor training. Recent attempts have been made in both animal

and human studies to further augment locomotor functioning in SCI

using afferent stimulation, either at the level of the dorsal roots using

transcutaneous spinal cord stimulation (TSCS) or with peripheral

nerve stimulation. The goal of this project was to develop a method to

optimize the stimulation parameters used to best improve stepping in

different individuals with incomplete SCI.

Tonic TSCS and/or phasic tibial nerve stimulation (TNS) was ap-

plied to subjects during stepping in the Lokomat gait orthosis at dif-

ferent frequencies (TSCS or TNS) and for different durations during

different portions of the gait cycle (TNS). Stimulation occurred in an

open-loop format initially and then was controlled based on force

feedback from the Lokomat (less force needed from the robot was

better) and on electromyography (EMG) from 8 leg muscles (the more

appropriate the timing of muscle EMG, the better). The optimization

algorithm then determined the best stimulation parameters to generate

the most normal muscle activity and the least robotic forces.

We have found that TSCS can modulate stepping in a stimulation

frequency dependent manner and can not only improve activation

patterns between muscles, it can reduce pathological states like clo-

nus. We also found that TNS was best at augmenting muscle acti-

vations and modulating force parameters when applied at frequencies

above 75 Hz, for less than 15% of the gait cycle, and timed at the

stance to swing transition.

With the development of optimization algorithms for neuromodu-

lation, we should be able to individualize, and adjust based on on-

going recovery, a novel intervention to facilitate the nervous system

that remains after incomplete SCI to best augment walking function.

Key words

human, locomotion, neuromodulation, robotics

OC6-03

INTRACRANIAL PRESSURE TREATMENT TAILORED TO

TRANSCRANIAL DOPPLER-DERIVED COMPLIANCE AND

PERFUSION

Kapinos, G.

1–3

, Sadoughi, A.

2

, Ullman, J.S.

1–3

, Narayan, R.K.

1–3

1

Hofstra North Shore-LIJ School of Medicine, Dept. of Neurosurgery,

Hempstead, USA

2

North Shore University Hospital, Manhasset, USA

3

Cushing Neuroscience Institute, Manhasset, USA

Transcranial Doppler (TCD)-derived parameters can classify pa-

tients into four categories: a group of patients at risk of raised in-

tracranial pressure (ICP) could benefit from ICP reduction by

osmotherapy alone, another group could benefit from blood pressure

augmentation alone, a third group would benefit from dual-targeted

treatment, while a fourth group with normal physiology could re-

ceive no treatment.

TCD was performed for non-invasive ICP monitoring in 5 patients

in our ICU with cerebral edema and risk for ICP-related ischemia,

but who were non-surgical or at high bleeding risk for ven-

triculostomy. Cases were 1 hepatic failure and 1 meningitis, both

with global cerebral edema (GCE) and hemispheric hematoma with

midline shift (MLS), 1 moderate traumatic brain injury (TBI) and 2

hypertensive hematomas with mass effect. TCD was used to derive

pulsatility index (PI) as a surrogate marker for brain compliance and

end-diastolic velocity (EDV) reflecting adequacy of cerebral perfu-

sion pressure (CPP). We applied therapeutic choices according to the

4 described categories to specifically address the cerebral needs of

each group.

One patient had no change in management because of normal PI

and EDV. Two received hypertonic saline along with induced hy-

pertension. One patient received mannitol and had vasopressors ta-

pered off to address break-through pressure edema. One patient

received hemodynamic augmentation for CPP amelioration. All pa-

tients had normalization of PI and EDV within our target range within

an hour of the tailored therapy. No patient had neurological deterio-

ration, worsening of GCE, MLS, new hemorrhage or developed in-

farcts within 48 h of our repeated interventions.

TCD was helpful to tailor a better suited therapeutic intervention

within this novel treatment paradigm. We propose to refine goal-

directed therapies for the pleiomorphic entity of cerebral blood flow

compromise instead of focusing solely on elevated ICP.

Key words

cerebral perfusion, compliance, goal-directed therapy, transcranial

doppler

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