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Importance of sample size for the estimation of repeater F waves in amyotrophic lateral sclerosis.

Fang J, Liu MS, Guan YZ, Cui B, Cui LY - Chin. Med. J. (2015)

Bottom Line: For each group, the Index RN and Index Freps obtained from 20 and 100 stimuli were compared.In the P group, the Index RN (P = 0.004) and Index Freps (P = 0.001) obtained from 100 stimuli were significantly higher than from 20 stimuli.For F waves obtained from 20 stimuli, no significant differences were identified between the P and NP groups for Index RN (P = 0.052) and Index Freps (P = 0.079); The Index RN (P < 0.001) and Index Freps (P < 0.001) of the P group were significantly higher than the control group; The Index RN (P = 0.002) of the NP group was significantly higher than the control group.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100730, China.

ABSTRACT

Background: In amyotrophic lateral sclerosis (ALS), repeater F waves are increased. Accurate assessment of repeater F waves requires an adequate sample size.

Methods: We studied the F waves of left ulnar nerves in ALS patients. Based on the presence or absence of pyramidal signs in the left upper limb, the ALS patients were divided into two groups: One group with pyramidal signs designated as P group and the other without pyramidal signs designated as NP group. The Index repeating neurons (RN) and Index repeater F waves (Freps) were compared among the P, NP and control groups following 20 and 100 stimuli respectively. For each group, the Index RN and Index Freps obtained from 20 and 100 stimuli were compared.

Results: In the P group, the Index RN (P = 0.004) and Index Freps (P = 0.001) obtained from 100 stimuli were significantly higher than from 20 stimuli. For F waves obtained from 20 stimuli, no significant differences were identified between the P and NP groups for Index RN (P = 0.052) and Index Freps (P = 0.079); The Index RN (P < 0.001) and Index Freps (P < 0.001) of the P group were significantly higher than the control group; The Index RN (P = 0.002) of the NP group was significantly higher than the control group. For F waves obtained from 100 stimuli, the Index RN (P < 0.001) and Index Freps (P < 0.001) of the P group were significantly higher than the NP group; The Index RN (P < 0.001) and Index Freps (P < 0.001) of the P and NP groups were significantly higher than the control group.

Conclusions: Increased repeater F waves reflect increased excitability of motor neuron pool and indicate upper motor neuron dysfunction in ALS. For an accurate evaluation of repeater F waves in ALS patients especially those with moderate to severe muscle atrophy, 100 stimuli would be required.

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Twenty consecutive traces exhibiting absence of F wave during a train of 20 supramaxiamal stimuli to the left ulnar nerve at the wrist in a 50-year-old male patient of the P group. A number of repeater F waves were obtained during the following 80 supramaximal stimuli. Letters to the right of record identify waves on the basis of waveform and latency. (a) F waves recorded from 20 stimuli; (b) F waves recorded from 100 stimuli. Calibration: M response: 5 mV/division, 5 ms/division; F waves: 500 μV/division, 5 ms/division.
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Figure 2: Twenty consecutive traces exhibiting absence of F wave during a train of 20 supramaxiamal stimuli to the left ulnar nerve at the wrist in a 50-year-old male patient of the P group. A number of repeater F waves were obtained during the following 80 supramaximal stimuli. Letters to the right of record identify waves on the basis of waveform and latency. (a) F waves recorded from 20 stimuli; (b) F waves recorded from 100 stimuli. Calibration: M response: 5 mV/division, 5 ms/division; F waves: 500 μV/division, 5 ms/division.

Mentions: The absence of F waves in a series of 20 stimuli was noted in the left ulnar nerves of 7 ALS patients with the relative preservation of CMAP. For the 7 patients, the strength of the distal upper limb with moderate to severe muscle atrophy ranged from 2 to 4 grades according to the Medical Research Council scale. The CMAP amplitude of the 7 ALS patients were significantly lower than the other 43 ALS patients (P = 0.002). Four patients belonged to the P group while the other 3 patients belonged to the NP group. There was no significant difference between the 4 patients in the P group and the 3 patients in the NP group for disease duration and CMAP amplitude. In the following 80 stimuli, a number of F waves were recorded with increased repeater F waves in left ulnar nerves of the 4 patients in the P group, while none or just 1 F wave was recorded in the left ulnar nerves of the 3 patients in the NP group [Table 2, Figures 2 and 3].


Importance of sample size for the estimation of repeater F waves in amyotrophic lateral sclerosis.

Fang J, Liu MS, Guan YZ, Cui B, Cui LY - Chin. Med. J. (2015)

Twenty consecutive traces exhibiting absence of F wave during a train of 20 supramaxiamal stimuli to the left ulnar nerve at the wrist in a 50-year-old male patient of the P group. A number of repeater F waves were obtained during the following 80 supramaximal stimuli. Letters to the right of record identify waves on the basis of waveform and latency. (a) F waves recorded from 20 stimuli; (b) F waves recorded from 100 stimuli. Calibration: M response: 5 mV/division, 5 ms/division; F waves: 500 μV/division, 5 ms/division.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4836257&req=5

Figure 2: Twenty consecutive traces exhibiting absence of F wave during a train of 20 supramaxiamal stimuli to the left ulnar nerve at the wrist in a 50-year-old male patient of the P group. A number of repeater F waves were obtained during the following 80 supramaximal stimuli. Letters to the right of record identify waves on the basis of waveform and latency. (a) F waves recorded from 20 stimuli; (b) F waves recorded from 100 stimuli. Calibration: M response: 5 mV/division, 5 ms/division; F waves: 500 μV/division, 5 ms/division.
Mentions: The absence of F waves in a series of 20 stimuli was noted in the left ulnar nerves of 7 ALS patients with the relative preservation of CMAP. For the 7 patients, the strength of the distal upper limb with moderate to severe muscle atrophy ranged from 2 to 4 grades according to the Medical Research Council scale. The CMAP amplitude of the 7 ALS patients were significantly lower than the other 43 ALS patients (P = 0.002). Four patients belonged to the P group while the other 3 patients belonged to the NP group. There was no significant difference between the 4 patients in the P group and the 3 patients in the NP group for disease duration and CMAP amplitude. In the following 80 stimuli, a number of F waves were recorded with increased repeater F waves in left ulnar nerves of the 4 patients in the P group, while none or just 1 F wave was recorded in the left ulnar nerves of the 3 patients in the NP group [Table 2, Figures 2 and 3].

Bottom Line: For each group, the Index RN and Index Freps obtained from 20 and 100 stimuli were compared.In the P group, the Index RN (P = 0.004) and Index Freps (P = 0.001) obtained from 100 stimuli were significantly higher than from 20 stimuli.For F waves obtained from 20 stimuli, no significant differences were identified between the P and NP groups for Index RN (P = 0.052) and Index Freps (P = 0.079); The Index RN (P < 0.001) and Index Freps (P < 0.001) of the P group were significantly higher than the control group; The Index RN (P = 0.002) of the NP group was significantly higher than the control group.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100730, China.

ABSTRACT

Background: In amyotrophic lateral sclerosis (ALS), repeater F waves are increased. Accurate assessment of repeater F waves requires an adequate sample size.

Methods: We studied the F waves of left ulnar nerves in ALS patients. Based on the presence or absence of pyramidal signs in the left upper limb, the ALS patients were divided into two groups: One group with pyramidal signs designated as P group and the other without pyramidal signs designated as NP group. The Index repeating neurons (RN) and Index repeater F waves (Freps) were compared among the P, NP and control groups following 20 and 100 stimuli respectively. For each group, the Index RN and Index Freps obtained from 20 and 100 stimuli were compared.

Results: In the P group, the Index RN (P = 0.004) and Index Freps (P = 0.001) obtained from 100 stimuli were significantly higher than from 20 stimuli. For F waves obtained from 20 stimuli, no significant differences were identified between the P and NP groups for Index RN (P = 0.052) and Index Freps (P = 0.079); The Index RN (P < 0.001) and Index Freps (P < 0.001) of the P group were significantly higher than the control group; The Index RN (P = 0.002) of the NP group was significantly higher than the control group. For F waves obtained from 100 stimuli, the Index RN (P < 0.001) and Index Freps (P < 0.001) of the P group were significantly higher than the NP group; The Index RN (P < 0.001) and Index Freps (P < 0.001) of the P and NP groups were significantly higher than the control group.

Conclusions: Increased repeater F waves reflect increased excitability of motor neuron pool and indicate upper motor neuron dysfunction in ALS. For an accurate evaluation of repeater F waves in ALS patients especially those with moderate to severe muscle atrophy, 100 stimuli would be required.

Show MeSH
Related in: MedlinePlus