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BioMed Central
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Trials
Open Access
Study protocol
New therapeutic approach to Tourette Syndrome in children based
on a randomized placebo-controlled double-blind phase IV study of
the effectiveness and safety of magnesium and vitamin B6
Rafael Garcia-Lopez*1, Emilio Perea-Milla2,3, Cesar Ruiz Garcia4,
Francisco Rivas-Ruiz2,3, Julio Romero-Gonzalez5, Jose L Moreno6,
Vicente Faus6, Guadalupe del Castillo Aguas7 and Juan C Ramos Diaz8
Address: 1Department of Anaesthesia and Reanimation, Hospital Costa del Sol, Ctra Nacional 340, km 187, 29603 Marbella, Spain, 2Research
Support Unit, Hospital Costa del Sol, Ctra Nacional 340, km 187, 29603 Marbella, Spain, 3CIBER Epidemiología y Salud Pública (CIBERESP),
Spain, 4Department of Paediatrics, Hospital Costa del Sol, Ctra Nacional 340, km 187, 29603 Marbella, Spain, 5Department of Paediatrics,
Children's and Maternal Hospital in Granada, Av. Fuerzas Armadas n° 2, 18014 Granada, Spain, 6Department of Pharmacy, Hospital Costa del
Sol, Ctra Nacional 340, km 187, 29603 Marbella, Spain, 7CS La Carihuela, Torremolinos, Spain and 8Hospital de Antequera, Av. Poeta Muñoz
Rojas, 29200, Antequera, Spain
Email: Rafael Garcia-Lopez* - drgarcia.anest@telefonica.net; Emilio Perea-Milla - eperea@hcs.es; Cesar Ruiz Garcia - cejutwo@hotmail.com;
Francisco Rivas-Ruiz - frivasr@hcs.es; Julio Romero-Gonzalez - julio.romero.sspa@juntadeandalucia.es; Jose L Moreno - jlmharo@hcs.es;
Vicente Faus - vfaus@hcs.es; Guadalupe del Castillo Aguas - gdelcas@teleline.es; Juan C Ramos Diaz - juancarlosramosdiaz@yahoo.es
* Corresponding author
Abstract
Background: Tourette Syndrome (TS) is a neurological condition presenting chronic motor and
phonic tics, and important degree of comorbidity. Considered an uncommon illness, it first
becomes apparent during childhood. Current standard treatment only achieves partial control of
the condition, and provokes frequent, and sometimes severe, side effects.
Methods and design: Main aim:
To show that, with respect to placebo treatment, the combination of 0.5 mEq/Kg magnesium and
2 mg/Kg vitamin B6 reduces motor and phonic tics and incapacity in cases of exacerbated TS among
children aged 7–14 years, as measured on the Yale Global Tic Severity Scale (YGTSS).
Secondary aims:
Assess the safety of the treatment.
Describe metabolic changes revealed by PET.
Measure the impact of the experimental treatment on family life.
Methodology: Randomized, blinded clinical trials. Phase IV study (new proposal for treatment
with magnesium and vitamin B6). Scope: children in the geographic area of the study group.
Recruitment of subjects: to include patients diagnosed with TS, in accordance with DSM-IV criteria
(307.23), during a period of exacerbation, and provided none of the exclusion criteria are met.
Instrumentation: clinical data and the YGTSS score will be obtained at the outset of a period of
exacerbation (t0). The examinations will be made after 15 (t1), 30 (t2), 60 (t3) and 90 days (t4).
Published: 10 March 2009
Trials 2009, 10:16 doi:10.1186/1745-6215-10-16
Received: 15 September 2008
Accepted: 10 March 2009
This article is available from: http://www.trialsjournal.com/content/10/1/16
© 2009 Garcia-Lopez et al; licensee BioMed Central Ltd.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0),
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Trials 2009, 10:16 http://www.trialsjournal.com/content/10/1/16
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PET will be performed at the t0 and t4. We evaluated decrease in the overall score (t0, t1, t2, t3,
t4), PET variations, and impact made by the treatment on the patient's life (Psychological General
Well-Being Index).
Discussion: Few clinical trials have been carried out on children with TS, but they are necessary,
as current treatment possibilities are insufficient and often provoke side effects. The difficulty of
dealing with an uncommon illness makes designing such a study all the more complicated. The
present study seeks to overcome possible methodological problems by implementing a prior, phase
II study, in order to calculate the relevant statistical parameters and to determine the safety of the
proposed treatment. Providing a collateral treatment with magnesium and vitamin B6 could
improve control of the illness and help reduce side effects.
This protocol was approved by the Andalusian Government Committee for Clinical Trials (Spain).
This study was funded by the Health Department of the Andalusian Regional Government and by
the Healthcare Research Fund of the Carlos III Healthcare Institute (Spanish Ministry of Health).
Trial Registration: Current Controlled Trials ISRCTN41082378
Background
Tourette Syndrome (TS) is a condition that was first
described in 1885 by Gilles de la Tourette as a clinical sit-
uation with significant tics, coprolalia and inappropriate
behaviour. For several decades, it was considered a psychi-
atric disorder. This situation changed in the 1960s with
advances in our understanding of neuroleptic drugs that
made it possible to achieve some improvement in the
symptoms presented by TS, now viewed as a neurological
disorder. This observation constituted the beginning of
the search for neurobiological factors for TS [1].
TS is currently considered a neurological condition with a
genetic background and varying degrees of penetration,
presenting chronic motor and phonic tics, sometimes
accompanied by a comorbid pathology, and with a natu-
ral rhythm of remissions and exacerbations [2,3].
Diagnosis of TS is a clinical decision; it is defined as the
presence of motor and phonic tics with an evolution
exceeding one year, appearing during infancy or child-
hood (always before the age of 18 years) and often accom-
panied by a comorbid neurological disorder. This
accompanying pathology is not always present, but nor-
mally determines the severity of the complaint. It consists
of the existence of an attention deficit/hyperactivity disor-
der (ADHD), an obsessive/compulsive disorder (OCD) or
other behavioural disorders such as poor control of
impulses or a tendency to self-harm [2].
Tics are believed to be the most frequently occurring neu-
rological disorder during childhood (up to 4%). Some
authors have calculated the prevalence of TS to be 4–5
cases per 10,000 persons, counting all ages, but it is more
frequent among children, affecting almost 1% of the juve-
nile population [4-7]. It predominantly affects males
(75%). There is a clear tendency for various members of
the same family to be affected, with varying degrees of
severity, and it has been related with many chromosome
sites, including 11q23. Symptoms among children are
more intense when the transmission is bilinear (maternal
and paternal) [2,8,9].
Tics can be motor and/or phonic, and may not initially be
recognized as such. They begin as simple motor tics, fre-
quently expressed by blinking or sniffing, while complex
motor tics take the form of coordinated movements of the
neck or unusual facial expressions. The presence of phonic
tics is a diagnostic criterion; sometimes, these are simple,
such as the emission of guttural sounds, while less fre-
quently they take complex forms like echolalia or copro-
lalia, which are the most striking manifestations of the
disorder. Although rare, the latter can have very negative
consequences for the social and emotional life of the
child.
Tics first appear at around the age of seven, beginning as
simple ones and subsequently becoming more complex.
By definition, they are long-lasting (more than one year's
duration). They tend to worsen and improve over periods
of two to three months. New tics may appear and others
disappear, or reappear later. In general, tics evolve from
simple to more complex forms, and from the head to the
lower limbs. Great distress is caused to the child, who tries
to suppress them, and may succeed for a limited time,
after which they may suddenly reappear, stronger than
ever. When tics are severe, they interfere with the life of the
child [1,10].
The natural evolution of TS generally begins with ADHD
at an early age (three or four years), with the first tics as
such appearing at seven or eight years, first in the form of
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simple motor tics affecting the face, and then complex,
intense and verbal. Subsequently, OCD may appear. The
condition worsens at the age of ten to fourteen years, and
usually improves by sixteen to twenty years. Fifty per cent
of such patients are free of tics by the age of eighteen years,
while the remainder continue to present the symptoms
during adult life, although generally in a less intense,
more manageable form that enables them to adjust and
enjoy a normal social, family and emotional life [2]. Typ-
ically, the condition worsens in situations of stress or
when catecolaminergic or corticoid medication is taken.
The pathogenesis of the complaint is not well understood,
although family incidence is evident. The natural evolu-
tion during puberty, together with the greater incidence of
tics among boys, are suggestive of a hormonal influence.
One factor suggested is that of a synaptic neurotransmitter
disorder resulting from the disinhibition of the cortical
striatal thalamic circuit, on the basis of the relative degree
of control achieved with neuroleptic medication [11-13].
Other possibilities suggested by the comorbid symptoma-
tology (ADHD and OCD) are the basal ganglia (caudate
nucleus) and the lower prefrontal cortex. However, post-
mortem examinations have failed to reveal specific altera-
tions. No models of TS have been observed among
animals. Neuroimaging studies are usually normal,
although the presence of tics has been related to the pres-
ence of asymmetry in the basal ganglia [14]. It has been
suggested that a disorder of the central neurotransmitters
may give rise to TS, as a response to the modulation of the
dopaminergic system; also mentioned as possible causes
have been low levels of serotonin, glutamate and AMP; on
occasion, too, PET has revealed an increased density of
transported presynaptic dopamine and of D2 postsynap-
tic dopamine receptors [15-17]. Autoimmune phenom-
ena have also been observed in this respect, with the
presence of antineuronal antibodies against beta-haemo-
lytic streptococci, as the case in other neurologic disorders
(such as Sydenham chorea). It is in this context that the
PANDAS syndrome (Paediatric autoimmune neuropsychiat-
ric disorders associated with streptococcal infections) has been
reported, although in the latter case, the appearance of tics
is much more brusque [18]. The results of complementary
studies of TS children are usually normal.
Treatment of TS is symptomatic. The tics are treated with
neuroleptic blockers of dopamine receptors (D2), such as
haloperidol. In recent years, other atypical neuroleptic
drugs (pimozide, risperidone) have been incorporated
into the treatment; these present fewer side effects,
although they are not totally free of adverse reactions [19].
Some side effects, such as tardive dyskinesia may be severe
and difficult to treat [20]. Clonidine (often with methyl-
phenidate) is commonly used to treat Tourette's syn-
drome [1,2]. These drugs have been applied both singly
and in combination, and in short term treatments (coin-
ciding with periods of exacerbation) and long term ones
[21-23].
ADHD is treated with amphetamines (methylphenidate)
[24]. OCD is alleviated with the administration of antide-
pressives to inhibit serotonin reuptake (fluoxetine)
[25,26].
In addition to pharmacological treatment, it is very
important to provide suitable educational counselling for
the child and his/her family. Cognitive-behavioural ther-
apy can achieve an improvement in the comorbid pathol-
ogy, especially as regards the obsessive-compulsive
disorder [10].
Background to the study
Other than in scientific texts, there exist anecdotal com-
munications of the experiences of parents of TS children,
reporting a significant decrease in the number and severity
of tics suffered when certain multivitamin and mineral
compounds were taken. This improvement, apparently,
was notable but not total, and the symptoms generally
reappeared when these substances ceased to be adminis-
tered. This kind of communication constitutes a new
physiopathological viewpoint, according to which a mag-
nesium insufficiency might be the principal causative fac-
tor and the common pathway leading to the symptoms of
TS and its comorbid pathology [27].
We wish to study whether any benefit is gained from the
oral administration of magnesium and vitamin B6 to TS
children. Both substances are commonly included in vita-
min supplements for children and adults, they are consid-
ered very safe and may be acquired without a medical
prescription.
Magnesium pidolate is taken as a syrup, at home. It is con-
traindicated for persons with illnesses such as decompen-
sated or acute renal insufficiency, myasthenia gravis,
diabetes or Cushing's disease. It should be utilized with
care for patients with irregular calcium metabolism. The
excipient may provoke allergic reactions, including
asthma, especially among persons allergic to acetylsali-
cylic acid. No side effects have been described for thera-
peutic dosages. It should not be administered in
conjunction with calcium (dairy products), which is prej-
udicial to its absorption.
Pyridoxine alpha-ketoglutarate could also be taken as a
syrup, at home. No contraindications or side effects have
been described, for therapeutic or even greater dosages. Its
excipient, too, may give rise to allergic reactions, includ-
ing anaphylaxia and bronchial spasms, especially among
patients with a previous history of allergy or of asthma. It
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should not be mixed with other medicines, in order to
preserve its absorption capacity.
We have designed a clinical trials to evaluate the effects of
magnesium and vitamin B6 supplements on the clinical
condition of children with TS. This supplementation is
authorized for children and already commercially availa-
ble; therefore, our aim in the present study is to confirm a
possible new indication. The study should include chil-
dren up to the age of 14 years, diagnosed with TS; this age
limit was chosen as it is then when a standstill or remis-
sion of the symptoms may occur. The minimum duration
of treatment and follow-up for these children should be
three months, in view of the natural evolution of the ill-
ness, with spontaneous remissions and exacerbations. The
symptoms most easily measured are the presence and
severity of tics.
We present a new therapeutic approach to TS, based on
the hypothesis that a deficit of vitamins or oligoelements,
or a reduction of their activity, aggravates this pathology
and often provokes severe comorbidity. Moreover, we
take into account that current treatment protocols are fre-
quently ineffective among many children and present
important potential side effects.
Thus, we propose the following:
Main goal – to show that, with respect to placebo treat-
ment, the combination of 0.5 mEq/Kg magnesium and 2
mg/Kg vitamin B6 reduces motor and phonic tics and inca-
pacity in cases of exacerbated TS among children aged 7–
14 years.
Secondary goals – to assess the safety of the treatment, in
terms of adverse events; to describe metabolic changes
resulting from the treatment, as revealed by PET; and to
measure the impact of this treatment on the quality of
family life.
Methods and design
Design
Type of clinical trials
Blind, randomized clinical study, Phase IV (new indica-
tion for supplementary magnesium and vitamin B6).
This study began in October 2007 and is currently in
progress.
Recruitment of patients
The patients to be included are those diagnosed with TS,
according to DSM-IV (307.23) criteria [28], currently in a
phase of exacerbation. The primary healthcare paediatri-
cians in the whole region were informed about the EECC,
so that patients could be referred to the clinics where the
study was being carried out. The doctors responsible for
making the scale evaluation when a patient was included
in the study referred him/her to the pharmacy department
to be included in one of the two study groups, using the
randomization table. Informed consent must be obtained
from parents or guardians, and none of the exclusion cri-
teria must be present. (See Figure 1).
Study subjects
Patients
Patients diagnosed with TS, aged 7–14 years, either sex,
with a minimum score of 40 points on the Yale Global Tic
Severity Scale (YGTSS) [29], among whom the onset of
clinical exacerbation has been observed.
Selection criteria
Criteria for inclusion
- Aged 7 – 14 years, either sex. This is the age bracket dur-
ing which the natural course of the illness is most exacer-
bated. Before the age of 7 years, the tics may not yet have
appeared (this generally occurs at the age of 5 – 7 years).
After 14 years, symptoms tend to stabilise.
- Informed consent of the child's parents or guardians,
and reasoned agreement with the child.
- Clinical diagnosis of TS, according to Diagnostic and Sta-
tistical Manual of Mental Disorders – Fourth Edition
(DSM-IV) criteria.
- Score of 40 or more on the YGTSS.
Criteria for exclusion
- Severe ADHD or OCD, not clinically controlled.
- Severe TDAH or TOC, not clinically controlled.
- Autism.
- Unrelated depression.
- Allergy to acetylsalicylic acid (due to the excipients
used).
Randomization criteria
- Criteria set out above (age, diagnosis, consent).
- Evidence of exacerbation (Score ≥40 on the YGTSS).
- No contraindication due to the exclusion criteria.
- Patients who fulfil these criteria will be included, ran-
domly, in one of the groups.
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Patients flowchartFigure 1
Patients flowchart.
RECRUITMENT OF PATIENTS
Age: 7-14 year s
Diagnosis of TS following DSM -IV cr it er ia
Infor m ed consent by par en ts
No criter ia for exclu sion ma tched
Exacer b ation a ccor d ing to pa r ent s
CONFIRMATION OF EXACERBATION
Evaluat ion of YGTSS b y r esear cher
If YGTSS 40
Enter the Tr ial (t 0)
Randomization, blinding, and
tr eat ment a llocation
EXPERI MENTAL GROUP
Magnesium pidolat e
solution 0.5 mEq/kg/d ay
Pyr oxidin e alpha-ketogluta r ate
solution 2 mg/k g/day
CONTROL GROUP
Pla cebo: solu tion simu lating
Magnesium p idolate
Pla cebo: solu tion simu lating
Pyr oxidin e alpha-ketogluta r ate
WITH DRAW AL OF PAT IENTS : side effects or worsening.
In both groups:
Concurrent medication permitted
t0 (star t, exacer bat ion) YGTSS (40) PET PG WBI
t1 (15 days) YGTSS
t2 (30 days) YGTSS
t3 (60 days) YGTSS
t4 (90 days) YGTSS PE PGW BI
DATA ANALYSIS
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Randomization, blinding and assignment to treatment group
Randomization will be centralized and performed imme-
diately after the inclusion of an eligible patient. The allo-
cation envelopes will be serially numbered to ensure that
allocation concealment is maintained within the phar-
macy department at each hospital. A set of opaque enve-
lopes marked with the letter A or B will be used to include
patients in either the experimental or the control group.
These envelopes will be kept in the pharmaceutical
department responsible for dispensing the corresponding
medication. Randomization to either the treatment or the
placebo group will only be performed when a patient, suf-
fering exacerbated TS, is considered eligible to receive the
medication included in this study.
Instrumentation
The clinical data and the YGTSS score at the onset of the
period of exacerbation of the clinical condition (t0) will
be noted. The parents/guardians will be informed, and on
receipt of their informed consent, the previously rand-
omized medication will be provided. This medication is
to be taken at the patient's home, and follow-up will be
performed, at the healthcare clinic, at 15(t1), 30(t2),
60(t3) and 90(t4) days. PET will be performed at the start
and end of the experimental period, for 15 patients. The
psychological impact of the treatment on the families con-
cerned will be measured using the Psychological General
Well-Being Index (PGWBI) [30].
Evaluations
The clinical diagnosis of TS will be confirmed, and the
YGTSS score ascertained, so that the patient may be
included in the study and any subsequent fall in the glo-
bal score recorded (at t0, t1, t2, t3 and t4). Metabolic
changes in baseline and post-treatment PET will be
recorded. The PGWBI will be determined at the start and
end of the study period.
Withdrawal of individual patients
Patients may withdraw from the study at any time, for any
reason and without suffering any sanction for doing so.
The researcher-collaborator, after consulting with the
principal investigator and the study coordinator, may also
interrupt the treatment programme if the fact of continu-
ing this treatment, in his/her opinion, would be prejudi-
cial to the patient's welfare. If a patient withdraws or is
withdrawn from the study, follow-up to day 90 should be
continued whenever possible.
Follow-up of patients who withdraw from the study
Any patients whose treatment is withdrawn will continue
to be followed up until the event in question is resolved
or until, in the researcher's opinion, important changes in
the patient's health state are unlikely to occur. The follow-
up reports at 15, 30, 60 and 90 days will be completed for
all patients who received medication (including placebo)
during this study.
Suspension of the study
Should there occur severe adverse events related to the
administration of the treatment, the study will be inter-
rupted, and the researchers and the coordinator will
decide whether to continue or not. Ultimate responsibil-
ity for this decision will rest with the coordinator. The rel-
evant clinical research ethics committees and the
healthcare authorities shall be informed of any decisions
taken to interrupt, abandon or continue the study.
Ethical criteria
Applicable regulations
The study will be carried out in accordance with the prin-
ciples of the Helsinki Declaration, specifically the EMEA/
CPMP declaration on the use of the placebo in clinical tri-
als, with respect to the revised Helsinki Declaration, and
in accordance with the guideline for Good Clinical Prac-
tice (CPMP/ICH/135/95 – 17 July 1996), as well as local
regulations.
Recruitment
The study protocol was submitted to the Ethics Commit-
tee of the Hospital Costa del Sol (Marbella, Spain) for
approval. Implementation of the study began after the
Spanish national healthcare authorities formally
approved it. Although patients will be informed that they
are free to abandon the study at any time, we shall seek to
recruit those offering the maximum probability of
remaining within the study until its conclusion.
Informed consent for minors
After identifying candidate patients for inclusion in the
clinical trial, the children will be given an oral and written
explanation of the study. The parents/guardians will be
provided with all available information and any comple-
mentary information they might require, and they will be
given an information sheet so that their informed consent
for the child to participate in the trial may be obtained.
Once this has been signed, the form should be given to the
researcher when the child attends the clinic for treatment
of exacerbated TS (t0).
Liability for injury
An insurance policy for civil liability will be subscribed to
cover any injuries that may arise from the performance of
the study.
Treatment details
Dosage and administration of medication
The medication used in the trial will be administered
orally, at the patients' homes. The following medication
will be provided:
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Magnesium pidolate 0.5 mEq/Kg/day, divided to be taken
twice daily. This should not be taken in conjunction with
calcium or dairy products.
Pyroxidine alpha-aketoglutarate 2 mg/Kg/day, once daily.
Preparation and labelling of treatment procedures
The medication for the trials will be prepared, labelled
and stored by the pharmaceutical service. The active prin-
ciples of the treatment group were obtained via commer-
cially available drugs. The placebo used was created in the
hospital's pharmacy department, emulating the excipients
and volume of the experimental medication. Procedures
for reducing the volume of medication per pack will be
implemented in accordance with ICH requirements. The
study coordinator will supervise all procedures applied in
this respect.
Other medication allowed
The patients will continue taking their usual medication
to control TS symptoms or associated comorbid patholo-
gies. Moreover, they will continue receiving any pre-exist-
ing psychological support treatment.
In addition, they will continue taking any medication pre-
scribed prior to their entering the study, for any other con-
current illness.
Specific methods
Evaluation of effectiveness
The clinical evaluation of the patients' tics will be carried
out by applying the Yale Global Tic Severity Scale (YGTSS)
[29]. This scale has been validated for the study of motor
and phonic tics for children with TS, in comparison with
other scales such as the Shapiro Tourette Syndrome Sever-
ity Scale and the Tourette Syndrome Global Scale. It was
designed for studying TS and other disorders that provoke
tics, and functions by evaluating the number, frequency,
intensity, complexity and degree of interference of motor
and phonic tics. The YGTSS is applied by means of a semi-
structured interview with multiple informants (generally,
the parents) who assess the child's tics over a period of at
least one week. The translation into Spanish and its adap-
tation to local conditions were previously validated by the
authors of the present paper, in a prior study [31].
Measurement instruments
The Yale Global Tic Severity Scale. The Spanish version
of the YGTSS will be used. Scoring on this scale ranges
from 0 to 100 points. A score of 40 or more on the YGTSS
at t0 is defined as a state of exacerbation and therefore a
necessary condition for the patient's inclusion in the
study.
PET will be carried out at the beginning and end of the
study in order to detect metabolic changes that may be
related to the effectiveness of the treatment. Qualitative
changes in the metabolism pattern within the prefrontal
cortex and in the basal nuclei will be evaluated. This will
be complemented with a quantitative study of the nor-
malized rates of metabolism in such zones.
The Spanish version of the Psychological General Well-
Being Index will be calculated for the parents, at the
beginning and end of the study in order to assess the psy-
chological repercussions of the treatment on family life
[30,32]. This scale indicates the subjective feelings and
psychological well-being (or otherwise) during the past
week.
Adverse events
Any adverse event notified spontaneously by the subject,
or observed by the researcher or by the research team will
be recorded on the form designed for this purpose. The
researcher will classify the intensity of adverse events in
accordance with the following scale:
- Mild: some discomfort experienced but not such as to
interrupt normal daily activity.
- Moderate: sufficient discomfort to reduce or notably
affect normal daily activity.
- Severe: provoking incapacity to work or perform normal
daily activity.
The periodicity of the event will be classified in accord-
ance with the following scale:
- Single occurrence: just one event, of limited duration.
- Intermittent: various episodes of an event, each one of
limited duration.
- Persistent, unlimited: an event that has persisted over time,
and is of indefinite duration.
For each adverse event, its relation with the medication
taken (definitive, probable, possible, improbable, none),
in the researcher's opinion, as well as any action taken as
a result, will be recorded on the data collection form. The
occurrence of an adverse event that is fatal, potentially
fatal or incapacitating, or that requires or prolongs hospi-
talization, or that provokes severe congenital anomalies
will be recorded as a "severe" adverse event (SAE).
All SAEs and unexpected adverse pharmacological reac-
tions (UAPR), defined as adverse events whose nature or
intensity is not in accordance with any adverse event
expected, will be notified by the researcher to the study
coordinator by phone, mail or fax as soon as is reasonably
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possible, but in any case within 24 hours of their occur-
rence.
Follow-up after occurrence of an adverse event
All adverse events will be observed until their remission or
stabilization. Depending on the circumstances, this obser-
vation might necessitate evaluation by and/or referral to
the patient's GP or to a specialist.
Procedures and control
Selection of subjects
Patients diagnosed with TS will be included in a prelimi-
nary "potential subjects" group. Before undertaking any
selection activity, written informed consent, signed and
dated, must be obtained from the parents or guardians.
The patients will be informed, before any action is taken,
of the purposes and structuring of the study, and any
doubts that might be expressed will be answered. It will be
stressed that they have the unconditional right to with-
draw from the study at any time. They will be asked to
return to the healthcare clinic to begin the study proce-
dure when they believe the child is entering a period of
exacerbation of TS.
Study periods
t0 Entry into the study
When the child's parents/guardians consider a period of
exacerbation is beginning, they enter the active phase of
the study. The YGTSS score is assessed, taking into account
that a score of at least 40 is a prerequisite for entry into the
study.
The baseline PET is carried out for patients included in
the study.
The PGWBI for the parents/guardians is calculated.
t1 At 15 days.
The YGTSS is calculated.
t2 At 30 days
The YGTSS is calculated.
t3 At 60 days
The YGTSS is calculated.
t4 At 90 days. End of study period.
The YGTSS is calculated.
PET control.
PGWBI for parents/guardians.
Data analysis
Calculation of the statistical power; establishing the sample size;
safety
The sample size was established by means of a prior pilot
scheme based on a phase II effectiveness trial, with 10
patients monitored over 3 months. There was found to be
an improvement of 50% on the baseline YGTSS score
(mean total number of tics 12.9 (SD = 11.20) in the exper-
imental group vs. 26.7 (SD = 7.38) in the control group).
For the present study, we calculated a mean score of total
tics of 13 (SD = 10) after 3 months for the experimental
group, and of 23 (SD = 10) for the control group, for a
level of significance of 0.05 and a statistical power of 0.8,
taking the least favourable case. On the basis of these data,
17 patients per group (34 in total) were needed. This sam-
ple size was then over-dimensioned to allow for a possible
dropout rate of 10%, and so the minimum sample size
was calculated to be n = 38 (19 patients per group).
General considerations
A descriptive statistical analysis will be performed, using
statistics of central trend and dispersion for the quantita-
tive variables, and frequency distributions for the categor-
ical ones, carried out separately for the experimental and
control groups. The baseline variables will be compared
using these techniques. A flow diagram will be drawn to
show the sequence from the initially eligible population
to the one finally included in the study (refusals, drop-
outs, lost to follow-up, etc.), in accordance with the crite-
ria of the CONSORT guidelines.
A comparison will be made of between-group differences
between the initial and final measurements for the diverse
elements of the Yale Scale, using unpaired nonparametric
tests. For the final within-group comparison, paired non-
parametric tests will be used non-parametric Repeat meas-
ures with adjustments for baseline imbalances and scores.
The same analysis will be performed for the index of psy-
chological well-being, measuring the repercussions of the
treatment on family life.
The principal outcome variable (POV) will be taken as the
change in the global score on the Yale Scale, adjusted for
the baseline values. A simple linear regression model will
be made for this POV, and the level of significance set at p
< 0.05. Subsequently, a multiple linear regression model
will be created, including the variable "Experimental/
Control Group", and adjusting for any baseline variables
that might be unbalanced. Statistical adjustment was per-
formed by means of a multivariate model including the
variable group (experimental and control) and concomi-
tant treatment (Yes/No).
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The safety of the treatment will be described in terms of
the percentage of adverse events, and according to levels
of assignation of responsibility.
Discussion
TS is considered to be a rare neurological illness, although
increasingly high rates of prevalence are being reported in
current studies. The condition is seldom diagnosed, due
to ignorance of its existence and characteristics [7]. Until
very recently, TS was only recognized as such for the most
severe cases, in which there was an important degree of
functional limitation and very evident coprolalia.
Although this situation is changing, TS is still considered
an uncommon disease.
Few clinical studies have been made with children,
because, in addition to the normal difficulties arising in
this kind of study (with adults), legal considerations must
be borne in mind, due to the logical necessity to protect
minors. Nevertheless, such studies are clearly needed [33].
TS is a neurological illness, and its physiopathological and
inherited alterations, as well as aggravating environmen-
tal factors, are increasingly well understood [10]. Effective
treatment is provided by dopamine post-synaptic D2
receptor-inhibiting neuroleptic agents [34,35]. Other
types of medication, such as anti-epileptic drugs, have
also been applied, although the evidence of their effective-
ness is less apparent [36,37]. However, the control of TS
symptoms provided by the latter kind of treatment is only
partial, and side effects such as sedation and dysphoria are
common, as are others that are potentially very serious
(tardive dyskinesia, arrhythmia or sudden death)
[20,38,39]. In view of these considerations, many other
forms of treatment have been studied, of varying nature
and effectiveness; these include drugs that act on the cen-
tral nervous system, botulinum toxin, acupuncture, plas-
mapheresis, conventional neurosurgery and, more
recently, deep brain stimulation [40-45]. This diversity
suggests that the illness is, as yet, poorly controlled, espe-
cially in the most severe cases.
The possibility of a complementary treatment with mag-
nesium and vitamin B6 would represent an important
improvement in controlling the illness, by reducing the
need for neuroleptic drugs and other medication; it would
also reduce the amount and severity of side effects.
The alternative therapy proposed in this paper is based on
theoretical principles, but also on specific communica-
tions and on a prior study, on which the present protocol
is based [27].
In clinical terms, magnesium deficiency is related to neu-
romuscular hyperexcitability, and may give rise to convul-
sions, chorea and athetoid movements. It has also been
related to biochemical and genetic alterations that may
provoke the symptoms evidenced by children with TS
[46].
The enzyme kynureninase requires the presence of both
magnesium and pyridoxal phosphate, and so in cases of
hypomagnesemia there are high levels of kynurenines in
the blood – which is the case with TS. Abnormally high
levels of kynurenines provoke anxiety, an increased
release of noradrenaline, locomotory hyperactivity, tics,
increases in quinolinic acid, heightened sexual activity
among females, reduced levels of serotonin and blocking
of the GABA receptors. Therefore, this enzyme has been
related to the presence of tics, anxiety and coprolalia-
copropraxia [47].
A deficit of magnesium reduces the activity of vitamin B6,
by inhibiting the activity of the alkaline phosphatase
required to achieve its active form in the tissues, pyridoxal
phosphate. A deficit of vitamin B6 activity has been related
with raised levels of kynurenines, spasmodic movements,
abnormal movements of the head, hyperirritability,
increased sympathetic stimulation and heightened sensi-
tivity to glucocorticoids. The symptoms worsen in situa-
tions of stress and with the administration of
catecolamines and glucocorticoids [48].
Magnesium deficit increases NMDA receptor activity, pro-
ducing greater neural excitability. In consequence, there is
heightened anxiety and orofacial tardive dyskinesia, an
increased release of dopamine, more defensive behaviour
and greater modulation of serotonin receptors. Further-
more, other symptoms may be affected, such as migraine,
which is more frequent among patients with TS [49].
This situation also raises the levels of substance P, and is
associated with defensive behaviour, heightened response
to stress and to allergenic phenomena.
It should be noted, however, that to date no clinical trials
have been published corroborating this hypothesis [50].
In view of the fact that current treatment with neuroleptic
medication only achieves partial effectiveness and may
cause severe side effects, we believe there is reason to carry
out clinical trials with the proposed, less aggressive, sub-
stances [38].
The composition of multivitamin and mineral com-
pounds is very diverse, but from a theoretical standpoint,
taking into account their pharmacological properties and
following the hypothesis set out above, we consider that
clinical trials should be focused firstly on the administra-
tion of magnesium and vitamin B6. Both substances
present a wide therapeutic margin and have very few side
Trials 2009, 10:16 http://www.trialsjournal.com/content/10/1/16
Page 10 of 12
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effects; moreover, they are authorized for similar indica-
tions among children and have a long history of therapeu-
tic use.
Magnesium ions are fundamentally intracellular or
located in the bones, with only 1% being extracellular; in
consequence, magnesium levels in plasma do not accu-
rately reflect the content in the body. Traditionally, it has
been used intravenously to treat severe nutritional deficit,
as an antiarrhythmic agent and in cases of eclampsia-
preeclampsia. Orally-administered magnesium has been
used as a nutritional supplement. It can be given to chil-
dren. It is contraindicated in cases of acute or chronic
decompensated renal insufficiency, myasthenia gravis,
diabetic coma and Cushing's disease. The recommended
physiological dose is 0.2–0.5 mEq/kg/day [51].
Vitamin B6 (pyroxidine) is a hydrosoluble vitamin with a
wide therapeutic margin. In clinical and pharmacological
trials, it has been shown to have interesting properties,
participating in oxidative deamination, transamination
and decarboxylation; it also participates in the decarboxy-
lation of glutamic acid to GABA, from DOPA to dopamine
and from 5-hydroxytrytophan to seratonin. It presents
anti-convulsant properties and seems to exercise a neuro-
protective and antitoxic effect. It can be administered to
children, and has been authorized for use to treat children
with alterations in character, language and behaviour;
learning difficulties; delayed learning to walk; convulsive
illnesses; intoxication of the central nervous system; trem-
bling; and Parkinson's disease. The dosage provided may
vary widely, as renal elimination ensures its toxicity is
minimal [52].
As the activity of magnesium is a consequence of its ion
fraction, it is mainly intracellular and bears little correla-
tion with the magnesium in serum. We do not believe
clinical conclusions can be drawn from the measuring of
magnesium levels in serum [53]. In the same way, deter-
mining the levels of vitamin B6 in serum would not be
useful, in view of the fact that the problem lies in the activ-
ity deficit [48].
The statistical parameters to be used in this protocol are
derived from the above-mentioned prior study carried out
by our research group; this was a phase II clinical trials of
the effectiveness and safety of the treatment in question. It
was useful for pre-determining the degree of improve-
ment that could be expected among the experimental
group and, therefore, the minimum sample size needed,
together with the mean and standard deviation values
measured on the YGTSS.
This prior study showed that the treatment produced a sig-
nificant decrease in the YGTSS score, with no side effects.
Nevertheless, this was a pilot study, with methodological
limitations that we seek to overcome in the present proto-
col [54].
In turn, the methodological instrument that will be used
was also developed in a previous study of ours, namely
the YGTSS translated into Spanish, adapted and validated
for the local population [31].
The population chosen for this study is deliberately
restricted, being limited to children aged 7–14 years,
which is the age group in which clinical exacerbation, in
theory, is greatest. By this limitation, we seek to obtain a
population group of very homogeneous characteristics
and, at the same time, one presenting severe symptoms,
defined as a high score on the YGTSS (≥40).
It may be difficult to recruit the necessary numbers of
patients for the sample size envisaged, given the nature of
the clinical condition, the relative rarity of its diagnosis
and the fact that children are involved. We hope to over-
come this difficulty by expanding the geographic scope of
the study and the number of medical personnel involved
in recruiting suitable patients.
The follow-up period of three months is based on the nat-
ural course of the illness, with exacerbations and remis-
sions lasting approximately this length of time. We
believe that if the patient enters the study at the onset of a
period of exacerbation, the YGTSS score will be high and
it will be easier to identify significant differences, with the
symptoms being controlled to a greater extent, and more
quickly, among the experimental group than among the
control group.
The reason for performing a PET on the experimental
group before and after the administration of the medica-
tion is to objectify the dopaminergic activity within the
basal nuclei and in the prefrontal cortex, as well as to
reveal any alterations occurring in these areas as a result of
the medication administered. However, these images are
of low specificity and might not enable clear-cut conclu-
sions to be drawn. Nevertheless, it seems reasonable to
attempt to support the results of the clinical evaluation
with these alternative, objective data. Be that as it may,
these images will be of use as a basis for subsequent stud-
ies [15,16].
It is also important to assess the repercussions on family
life (which tends to be greatly impaired in severe cases) of
an improvement in the control of TS symptoms among
children. The PGWBI reflects psychological well-being (or
otherwise); it is based on theories of evaluation of the
domestic environment and is an appropriate means of
determining the distortion produced by TS within the
Trials 2009, 10:16 http://www.trialsjournal.com/content/10/1/16
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household [30,32]. We have no doubt that a direct corre-
lation will be found between the children's symptoms and
the psychological well-being within the family home.
The joint application of these three measurement meth-
ods, namely the objectification of tics and incapacity, the
assessment of metabolic changes in the circuits of the
basal ganglia and of the cortex, and the evaluation of
stress within the family, will enable us to reach an objec-
tive judgement as to the effectiveness of the treatment
being tested.
In summary, treatment for TS continues to present impor-
tant shortcomings and further clinical trials are necessary
in this respect, especially among children.
Abbreviations
ADHD: Attention deficit/hyperactivity disorder; CON-
SORT: Consolidated Standards of Reporting Trials; DSM-
IV: Diagnostic and Statistical Manual of Mental Disorders;
GABA: Gamma aminobutyric acid; MPA: Monophosphate
adenosine; NMDA: N-methyl-D-aspartate; OCD: Obses-
sive compulsive disorder; PANDAS: Paediatric autoim-
mune neuropsychiatric disorder associated with
streptococcal infection; PGWBI: Psychological General
Well-Being Index; POV: Principal outcome variable; SAE:
Severe adverse event; YGTSS: Yale Global Tic Severity Scale
Competing interests
The authors declare that they have no competing interests.
Authors' contributions
RGL, JRG Clinical review of the subject and previous con-
sideration. RGL, JRG, EPM, CRG, FRR Development of the
phase II prior study. EPM, FRR, RGL Methodological
design. CRG, RGL Preparation of documentation. CRG
Preparation of the International Registry entry of the clin-
ical trial. RGL, CRG, JRG Training with and standardiza-
tion of procedures and clinical measurement
instrumentation (YGTSS). CRG Review and design of the
PET evaluation. JLM, VF, RGL Review and decision mak-
ing standpoint on medication.
Acknowledgements
This protocol is approved and funded by the Carlos III Health Institute
Healthcare Research Fund (PI06/90242) and by the Health Department of
the Andalusian Regional Government (0382/2006).
The authors wish to thank the following for their support: the Andalusian
Tourette Syndrome and Associated Disorders Association; the Costa del
Sol Hospital (part of the Andalusian Public Health Service). We thank Glenn
Harding for the professional translation of the paper.
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