Effect of Deep Brain Stimulation on Parkinsonian Tremor
The recordings of this database are of rest tremor velocity in the index
finger of 16 subjects with Parkinson's disease (PD) who receive chronic
high frequency electrical deep brain stimulation (DBS) either uni- or
bi-laterally within one of three targets:
- Vim = the ventro-intermediate
nucleus of the thalamus (n=3),
- GPi = the internal Globus pallidus (n=7), or
- STN = the subthalamic nucleus (n=6).
This surgical procedure involves implanting an electrode into
subcortical structures (Vim, GPi or STN) for long-term stimulation at
frequencies greater than 100 Hz. The mechanism by which high frequency
DBS suppresses tremor and reduces other symptoms in PD is unknown.
Parkinson's disease is characterized by the progressive loss of dopamine
neurons in the substantia nigra of the midbrain, and is associated with
motor symptoms including tremor (usually rest tremor, though sometimes
postural tremor), bradykinesia and rigidity. In
Parkinson's disease, tremor becomes more regular or harmonic, its
frequency is shifted to a lower range (typically 4-6 Hz), its amplitude
increases, the shape of its oscillations changes, and it fluctuates over
time. These changes are subtle and intermittent at first, becoming more
permanent and obvious as the disease progresses.
Figure 1. Two seconds of Parkinsonian rest tremor velocity
(metres/second) recordings from subject g2 (stimulator implanted in the
GPi) under four conditions: (a) no stimulation and no medication, (b)
deep brain stimulation and no medication, (c) no stimulation and 150%
medication, (d) deep brain stimulation and 150% medication. Note the
zoomed vertical scale in (b), (c) and (d).
Chronic high frequency deep brain stimulation of the Vim can decrease
tremor amplitude in a spectacular way. Deep brain
stimulation of the GPi and STN have been shown to relieve not only
tremor but also other symptoms of PD such as rigidity and dyskinesia.
See Figure 1 for an example of the effect of deep brain stimulation of
the GPi on tremor.
Figure 2. Velocity laser recording of rest tremor.
The raw data were obtained using a
low intensity velocity-transducing laser that was directed at a piece of
reflective paper on the subject's index finger tip (Figure 2), with the output
voltage proportional to the velocity of the finger.
DBS/Medication Conditions:
Tremor was recorded for approximately 60 seconds under various
conditions:
- two conditions of DBS (on-off) and two conditions of medication
(L-dopa on-off)
[total: 55 recordings of approx 60 seconds each]
- every 15 minutes when DBS was stopped for 60 minutes (medication off)
[total: 46 recordings of approx 60 seconds each]
Please note that not all subjects were tested under all conditions.
For the "medication off" condition, the subject did not take
any medication for at least 12 hours. For the "medication on"
condition, the subject took 150% of his or her morning dose of
dispersible Modopar and testing began after the neurologist determined
the medication had taken effect (approximately 40 minutes).
Subjects:
The 16 subjects can be divided into two groups:
- Subjects 1-8 with high amplitude tremor (HAT) who are receiving DBS
to relieve tremor (Group 1), and
- Subjects 9-16 with low amplitude tremor (LAT) who are receiving DBS to
relieve other symptoms such as rigidity or dyskinesias (Group 2).
The file subject_description.txt
contains information on the 16 subjects:
| Information | Description |
|---|
| SUBJECT | 2 character subject identification:
Stimulation target (v=Vim, s=STN, g=GPi), and
Subject number (1-16) |
| AGE | Age at the time of testing (years) |
| GENDER | Male (n=11) or female (n=5) |
| STIM TARGET | Vim = ventro-intermediate nucleus
of the thalamus
GPi = internal Globus Pallidus
STN=subthalamic
nucleus |
| BI/UNI-LATERAL | Bilateral stimulation (n=12) or
unilateral stimulation (n=4) |
| EFF FREQ | Frequency (Hz) of effective
stimulation (> 100 Hz) |
| INEFF FREQ | Frequency (Hz) of so-called ineffective
stimulation (< 100 Hz) |
| INTENSITY | Stimulation intensity (V) |
| PULSE WIDTH | Stimulation pulse width (µsec) |
| MODE | Cont = continuous
stimulation,
Cycl=cyclic stimulation (e.g. 1 minute on, 1 second
off) |
| STIM CONTACTS | Listed in order of proximal
distal direction on quadripolar stimulating electrode:
- negative polarity
+ positive polarity
. not stimulated
|
| YEAR DIAGNOSED | Year diagnosed with
Parkinson's disease |
| YEAR DBS RIGHT | Year of right brain DBS surgery |
| YEAR DBS LEFT | Year of left brain DBS surgery |
| TOT DAILY MED | Total medication of morning,
noon and evening doses (mg) |
| 150% SINGLE DOSE | Dose taken before testing
"medication on" condition (mg) |
Filename Structure:
The file name structure of the records is:
- 2 character subject identification: stimulation target (v=Vim,
s=STN, g=GPi) and subject number (1-16)
- 1 character tremor type: r = resting tremor
- 1 character DBS condition: e = effective (> 100 Hz), o = no
stimulation
- (optional) 2 character time since stimulator arrest: if a 2 digit
number follows the DBS condition, it indicates the number of minutes
since the stimulation was stopped
- 1 character medication condition: n= medication on, f=medication
off
- 3 character extension indicates the side tested: let = left index
finger tremor, rit = right index finger tremor
Filename Examples:
- s6ren.let contains a recording
(approx. 60 sec) of rest tremor in the left index finger of subject 6 in
the "dbs on and medication on" condition: the subject had
taken 150 % of his or her morning dose of L-dopa and was receiving
"effective" stimulation of the STN.
- v4rof.rit contains a recording
(approx. 60 sec) of rest tremor in the right index finger of subject 4
in the "dbs off and medication off" condition: the subject was
off medication for at least 12 hours and the subject's stimulator
(implanted in the Vim) was switched off.
- g1r30of.rit contains a recording
(approx. 60 sec) of rest tremor in the right index finger of subject 1 at
30-minutes after the stimulator (implanted in the GPi) was switched off.
Also, this subject was off medication for at least 12 hours.
Tremor Recordings:
The rest tremor recordings can be classified as one of 8 categories, for
subjects with high amplitude tremor (HAT) and for subjects with low
amplitude tremor (LAT):
- ren: Deep brain stimulation on, Medication on
HAT subjects: n=5 recordings
LAT subjects: n=8 recordings
- ref: Deep brain stimulation on, Medication off
HAT subjects: n=5 recordings
LAT subjects: n=8 recordings
- ron: Deep brain stimulation off, Medication on
HAT subjects: n=7 recordings
LAT subjects: n=8 recordings
- rof: Deep brain stimulation off, Medication off
HAT subjects: n=6 recordings
LAT subjects: n=8 recordings
- r15of: Deep brain stimulation off for 15 minutes,
Medication off
HAT subjects: n=3 recordings
LAT subjects: n=8 recordings
- r30of: Deep brain stimulation off for 30 minutes,
Medication off
HAT subjects: n=4 recordings
LAT subjects: n=8 recordings
- r45of: Deep brain stimulation off for 45 minutes,
Medication off
HAT subjects: n=3 recordings
LAT subjects: n=8 recordings
- r60of: Deep brain stimulation off for 60 minutes,
Medication off
HAT subjects: n=4 recordings
LAT subjects: n=8 recordings
| Total: | HAT subjects: n=37 recordings
LAT subjects: n=64 recordings |
The file file_description.txt
contains a summary of recordings per subject in each category.
Reference:
Beuter, A., Titcombe, M.S., Richer, F., Gross, C., Guehl, D., 2001.
Effect of deep brain stimulation on amplitude and frequency
characteristics of rest tremor in Parkinson's disease.
Thalamus & Related Systems, Volume 1 (3): 203-211
(published by Elsevier Science).