[Abstract Title]. - Society for Neuroscience

Time: Sunday, November 16, 2008, 1:00 pm - 5:00 pm
Program#/Poster#: 272.2/II1
Topic: D.12.b. Diseases
Support: Cleveland Clinic grant (RPC6700)
Department of Defense grant (DAMD17-01-1-0665)
NIH grant (NS37400)
Title: Motor task failure in cancer related fatigue is more attributed to central than muscular
fatigue
Authors: *V. SIEMIONOW 1,2 , K. KISIEL-SAJEWICZ 1,4 , A. WYANT 1 , V. K.
RANGANATHAN 2 , J. HOU 2 , D. SEYIDOVA-KHOSHKNABI 3 , M. T. DAVIS 3 , T. D.
WALSH 3 , G. H. YUE 1,2 ;
1 Dept Biomed Eng, 2 Physical Med. and Rehabil., 3 Harry R. Horvitz Ctr. for Palliative Med.
Taussig Cancer Ctr., The Cleveland Clin., Cleveland, OH; 4 Kinesiology, Fac. of Physiotherapy,
Univ. Sch. of Physical Educ., Wroclaw, Poland
Abstract: Our group observed impaired neuromuscular junction (NMJ) transmission function
and worsened central fatigue with minimal muscle fatigue during voluntary motor activities in
patients with cancer-related fatigue (CRF). Based on these findings, we hypothesized that muscle
signals during prolonged motor activities in CRF would experience less changes compared with
healthy controls. Twelve patients with CRF and 12 age- and gender-matched healthy controls
performed a sustained isometric elbow flexion contraction of the right arm at 30% maximal level
(S30) until self-perceived exhaustion. During the S30, surface EMG signals of the elbow flexor
and extensor muscles and elbow flexion force were recorded. EMG amplitude and power at
peak, median and mean frequencies were analyzed at the beginning (non-fatigue condition) and
end (fatigue condition) of the S30. Similar to the reports in the literature, the median frequency
decreased with muscle fatigue in both groups. However, the value of the median frequency in
CRF under the non-fatigue condition was similar to the median frequency in controls under the
fatigue condition of the S30. The power at both the peak and median frequencies was similar
between the two groups at the beginning of the S30 but the patients experienced a significantly
smaller increase in median power of the frequency spectrum (from 1.92 mV 2 to 8.23 mV 2 ) than
the control subjects (from 2.21 mV 2 to 13.87 mV 2 ) at the end of the S30. Similarly, the mean
power of the spectrum increased from 0.273 mV 2 to 1.029 mV 2 for CRF group and 0.362 mV 2 to
3.76 mV 2 for controls. Furthermore, the amplitude (root mean square) of the EMG was similar
between the two groups at the beginning of the S30 but it had a significantly smaller increase at
the end of the S30 in CRF versus control group. Finally, at the end the S30, frequencies of the
peak and median power, the power values, and EMG amplitude in CRF were not much different
from the corresponding values of the controls at the beginning of the S30. These findings suggest
that although the CRF patients and controls had a similar level of perceived fatigue (they felt
exhausted and terminated the S30), the level of muscle fatigue at the end of the S30 was less in