Botulinium toxin injections
Currently, the most effective technique in the prevention of facial ageing is the injection of botulinum toxin (often called “botox” after a brand name). This is a substance that reduces muscle contraction by intervening at a neuromuscular level (myorelaxant action).
In 1973, SCOTT began using medical injections of botulinum toxin in strabology. Nowadays, the use of the Botulinum toxin in serious and acute strabismus means that surgery can be avoided in 80% of cases.
The use of botulinum toxin in aesthetic treatment began in Canada in 1987 when Jean and Alastair CARRUTHERS, ophthalmologist and dermatologist respectively, noticed that a patient treated for blepharospasms (permanent contraction of the eyelid) no longer had crows’ feet. That is when they began using botulinum toxin in aesthetics, in order to prevent further ageing by decreasing the contraction strength of the facial expression muscles.
Since then, millions of injection sessions have been carried out and gradually, the organisations responsible for healthcare in numerous countries have acknowledged the good safety aspect and retrospective knowledge of the product and consequently authorised its use in aesthetic treatments for inter-eyebrow wrinkles for example: USA , Canada , Switzerland , France …
In February 2003, the French administrative authorities responsible for monitoring medicines gave its AMM (authorised the launch of this product for the first time on the market for aesthetic use by the laboratory ALLERGAN under the name of VISTABEL). This AMM covers the use for aesthetic treatment of glabella wrinkles under certain conditions for practitioners and with certain modalities of use. Injections made as part of aesthetic treatment on other anatomic areas are made out of the AMM.
Since 2005 and the works of the Le Louarn/Buthiau/Buis team on the Face Recurve® concept, the use of botulinum toxin has found two new fields of application: as a preventive treatment before any signs of structural ageing appear (tear troughs, naso-labial folds, bitterness folds, platysma band…) and towards muscle regeneration blockade to stabilize the aesthetic or curative effect of certain targeted surgical resections.
Principles of action and indications for Botulinum toxin
How does it work?
Wherever the botulinum toxin is injected it blocks the release of acetylcholine, indispensable for muscle contraction.
Everyone has two eyes, a nose and a mouth, yet there are endless variations of shape and facial expressions that are unique and specific to each and every one of us. It follows that each of us has our own anatomic particularities both when at rest and when moving. By specifically studying a patient’s face and expressions, the practitioner can determine the position and dynamics of a muscle. These two components enable him/her to assess exactly where the injection should be made and the amount of product to be used.
Sometimes it is said that botulinum toxin makes faces look “fixed” and unnatural, but this happens in the main when injections are performed using a pre-defined schema (the same for all patients).
The procedure for the tailor-made injection of botulinum toxin is more sophisticated. More than anything it obviously requires that a surgeon be trained to inject the toxin for aesthetic purposes and, more specifically, for anatomic function. Participation by the patient is also required, since he or she will be asked:
• to come for an initial informative consultation during which every possible botulinum toxin treatment is discussed, together with the benefits and risks of the injection;
• to finalize the “map” of desired effects with the practitioner once he has been taken the decision to proceed with the injection;
• to return for follow-up consultations one month after the injection so that the practitioner and himself can assess the overall results and prepare for the second injection session in function of the effects of the first session.
Botulinum toxin treatments are therefore conceived and managed over time, as it is sometimes necessary to hold several injection sessions before being able to adapt the use of the product to its fullest potential.
What do the injections treat?
Botulinum toxin injections are used in aesthetics to obtain 5 different effects that are explained below:
• action against expression wrinkles: reduced muscle strength contraction,
• harmonisation of the face: balancing of muscle action,
• improved skin hydration at epidermal level via anticholinergic action,
• reduced resting muscle tone: prevention of structural ageing,
• blockade of muscle regeneration to stabilize the surgery-induced neutralization effect on age marker fascicles.
1) Action on expression wrinkles:
See presentation on Botulinum toxin and facial expression wrinkles:
Example with action on glabella (lion’s wrinkle)
This is the most widely known effect of the Botulinum toxin. It is used for the lion’s wrinkle, crows’ feet, horizontal forehead wrinkles, and lines around the mouth.
To act on an expression wrinkle, the surgeon determines the exact position of the muscle that produces an expression by asking the patient to pull a face.
Over time, the repetition of contractions caused by expressions is responsible for a slight persistence of muscle contraction, even when the face is relaxed. As a result, the skin associated with this muscle stays crumpled even when relaxed. Added to that is the skin “breaking” effect due to repeated contractions involving the same spot over and over botulinum toxin therefore affects facial expression wrinkles in two ways: by allowing the muscle to release its tension more completely at rest, thereby “smoothing out the features”, and also by reducing the contraction strength through a reduction or even eradication of skin fracture, i.e., wrinkle formation.
The key objective of this treatment is to improve wrinkles and fine lines when the face is at rest and not to prevent muscular contractions altogether. The results will therefore mainly be based on the appearance of the wrinkles when the muscles are relaxed, overall blockade not being recommended in most localisations so as not to cause a “frozen-look” appearance.
2) Harmonisation of the face
See video on Botulinum toxin used to harmonize facial feature:
Example of action on eyebrow levator and depressor muscles to obtain symmetry
A face is generally considered as being as beautiful or as pleasant as it is symmetrical. This is perfectly logged in the work by Jean-François Amadieu: “The weight of appearances”.
Botulinum toxin enables facial asymmetries to be tackled by modifying muscular balance.
The relaxed position of many facial elements is determined by the balance between a levator muscle and a depressor muscle (the position of eyebrows, the wings of the nose, the corner of the eyes, the corners of the mouth, etc.). Action on the levator or depressor through botulinum toxin injections enables the face to be harmonised by playing on muscular balance.
It is therefore possible, in most cases, to raise or lower each eyebrow as one wishes to, the corners of the eyes, the wings of the nose or the corners of the mouth. ..
It is equally possible to rebalance the face in case of facial palsy, a cause of facial asymmetry.
3) Skin hydration (mesobotox)
See video on Botulinum toxin used to improve skin hydration:
Example of action of neckline
The Botulinum toxin also acts on the epidermis by heightening skin hydration through its anti-cholinergic action.
The Botulinum toxin injection into the epidermis acts on the myofibroblasts, giving them a younger structure. It “re-inflates” the skin. It is this effect that is sold in “botox-like” creams.
The direct injection of the Botulinum toxin is clearly more effective than using a cream, but it also is limited in its surface area of application. In fact, the toxin is a medicine and should not be used in doses greater than its prescription conditions. Positive results can be achieved, whilst remaining sensible, when treating neckline wrinkles, creasing at the top of the forearms and not too accentuated creases of cheeks when smiling. This treatment is particularly useful, because surgery is not always possible on those areas.
4) Action on resting tone to prevent structural ageing induces by the AMFs
See Video on Botulinum toxin used to diminish resting tone:
Example of action on LAN (levator alaquae nasi) muscle to reduce the naso-labial fold
The foremost role of certain fascicles of mimic muscles in structural ageing of the face has been evidenced during studies on Face Recurve® . These fascicles have been named Age Marker Fascicles (AMF).
These AMF are the primary cause of paramedian structural ageing of the face. They are directly involved in the occurrence of bags under the eyes, the tear troughs, the naso-labial folds, the bitterness folds, the jowls and cervical bands. Inasmuch as these fascicles were proved not to be indispensable (their functional role being weak or nil), it has become possible to interfere with their deleterious action at the root of structural ageing by causing a weakening thereof or by sectioning the same without any prejudice to the patient, while preserving the desired natural facial expression.
In young subjects, facial expression muscles are curved and long (flexible) at rest; they cover the deep fat layer that forms important masses, whereas the superficial fat layer is regular and thin. In order to form its expression, the muscle of interest has to retract, thereby shortening itself and becoming rectilinear. Therefore, it presses down on the underlying deep fat tissue during motion.
At length, following repeated contractions, the muscle no longer can relax completely: it loses its natural convex shape and becomes shorter, straighter, and more rigid in elderly subjects. It is said to have increased resting tone (it remains tonic when it should relax). Moreover, with repeated contractions, the deep lying fat is less and less apt to retrieve its natural place under the muscle, thereby creating superficial fatty masses on either side thereof.
For example, on the oval of the face, the shortened muscle creates the bitterness fold, while the fat tissue volume that is displaced forms the jowls. Unfortunately, this phenomenon is the more effective as each of these outstanding features accentuate the visibility of the other.
To make structural ageing even worse, this mechanism is not uniform over the whole muscle area, and it is much more enhanced where at specific fascicle of the expression muscle that were named Age Marker
Fascicles. Deep furrows are thus formed that reinforce this phenomenon even further whereby the passing of the time is revealed.
Gravity comes into play later to affect the cutaneous and fat tissues already damaged by the action of the age marker fascicles and to create facial ptosis.
The drastic change brought about by Faced Recurve® in the concept of the structural ageing mechanism has, in course, lead to the development of new medical and surgical techniques in the struggle against the untoward action of the age marker fascicles. On this occasion, the indications for Botulinum toxin in aesthetics have been broadened to include preventive treatment against the shortening of these age marker fascicles.
The principle of preventing programmed structural ageing consists in acting on the fascicle resting tone to prevent it from remaining contracted in between facial expressions (when no particular face expression is wanted). This effect is obtained without reducing the maximal muscle contraction strength and, hence, without diminishing the expressiveness of the contracted facial expression. The injections administered in this indication contain much lower doses but are much better targeted and more precise (depending on the analysis of the face expressions of each patient and, therefore, on the specific ageing features expected).
When the botulinum toxin is used at stage 0 (i.e., preventively at around ages 25–30 years) of structural ageing, the term used is Toxin Recurving® . This type of injection has barely any effect on the facial appearance (the result is little visible at rest and not at all upon contraction), and is therefore recommended only for those persons whose physical appearance plays a major role professionally and who are motivated by the preventive aspect of the treatment.
5) Muscle regeneration blockade after localised Face Recurve® surgery or after Face Recurve® Lift:
Play video on botulinum toxin and muscle regeneration blockade
following Face Recurve® surgery to prevent secondary structural ageing
Example of action on DAO (depressor anguli oris) to consolidate results on jowls and bitterness folds
Works carried out by the Le Louarn/Buthiau/Buis team have provided for identifying age marker fascicles (AMF) as being responsible for the structural ageing of the paramedian region of the face. These fascicles are directly implicated in the occurrence of bags under the eyes, tear troughs, naso-labial folds, bitterness folds, jowls and cervical bands.
During the surgical treatment of structural ageing conducted according to Face Recurve® principles, for lasting results botulinum toxin must be used to block later muscle regeneration.
Actually, this type of surgery is based on the neutralization of age marker fascicles by specific surgical section, and on the correction of fat tissue displacement induced by the same fascicles. Surgeons had learned from experience, both on pathological and cosmetic cases, that muscle sectioning was not effective most of the times because the natural regeneration would obliterate or limit the effect.
Once the determinant role of the AMFs in structural ageing of the face had been identified, it became essential, if one wanted to act effectively against their deleterious effect, to find adequate operative techniques to cut those fascicles in a targeted manner and to neutralize also the natural regeneration thereof.
A study of the very great number of works carried out in sports traumatology shows that the fact of putting a muscle to rest during the initial phase of healing (after an accident) prevents later recovery, and that the muscle should be made to move very quickly following a trauma in order to obtain recovery. It seemed therefore logical, if one wanted to obtain the reverse effect, to put the muscle concerned by structural ageing to rest. The only obvious means to do that without forcing the patient to remain motionless for 3 months was to used botulinum toxin.
Apart from indications in cosmetic surgery, the blocking of muscle regeneration provides new applications in pathology, namely as regards the treatment of facial palsy.
In the case of unilateral facial palsy, one may observe exacerbated reactive functioning on the side not affected by the paralysis. This marked facial expression on the healthy side causes the paralysis to be even more apparent. In order to minimize the dissymmetry, reconstruction surgeons have begun by weakening the muscles on the healthy side, which yielded disappointing results because of the muscle regeneration. Therefore, more complicated, heavier surgical procedures had to be performed, i.e., selective neurectomy. In French, this is the sectioning of all the nervous fascicles innerving one muscle and only that one muscle. Actually, the fact of not sectioning merely one of those fascicles will allow muscle function recovery. Conversely, excess sectioning may cause adjacent disturbances. The discovery of muscle regeneration blockade in cosmetic surgery through the works of Face Recurve® has opened a new path towards simplified corrective procedures in facial palsy, as simple muscle sections had become effective.
For recall, Face Recurve® offers an intermediate stage in the treatment of structural ageing between cosmetic surgery (toxin injection and fillers) and the lift. Before excess skin becomes apparent, an action on the paramedian furrows may be undertaken via specific surgical sectioning of the marker fascicle at cause, combined with replacement of the fat tissues that have been expelled through muscle contractions. Thus, the natural muscle convexity can be restored and structural ageing is managed locally without having to exert any skin traction associated with substantial scarring (since no lift is performed), and by using merely localized actions. In order to treat the naso-labial fold, a small, nose-hidden incision is performed, and to correct the jowl and bitterness fold an inner-mouth approach is used; finally, to act on the cervical bands, a small scar is placed under the chin.
When structural ageing is of longer standing, there is some excess skin induced which is secondarily made worse by gravity. Muscle sections and fat volume replacements specific to Face Recurve® must then be combined with the resection of this excess skin and, hence, with lifting. This is referred to as the Face Recurve® Lift.
Thanks to targeted marker fascicle sectioning and fat tissue replacement there is no need for the lift traction to remove the sequellae due to the action of the face expression muscles. The lift procedure is thus strictly limited to the excess skin removal.
The risk for obtaining a “drawn up” look which used to occur with the conventional technique is therefore avoided, as the effect sought at the time had to be a polished one and that, consequently, the skin was being pulled up excessively to exert an effect on the marked median fold through skin traction. With the Face Recurve® Lift, the excess skin is removed and the masses are replaced while strictly respecting their initial place and volume. The anatomic structure is thus restored as closely as possible to that of the young subject’s, while the sectioning allows for counteracting the untoward action of the marker fascicles, thus preventing further ageing. The outcome is more effective, natural-looking and stable.
The procedure requires one or two nights of hospitalization. It is carried out under general anaesthesia or under assisted local anaesthesia, depending on the case.
For more information on the Face Recurve® concept and/or on surgical rejuvenation of the face, please refer to the articles under the same names.
With botulinum toxin, it is better to treat the patient progressively and avoid the risk of any “counter effect” during the first injections, as it is not yet possible to asses the specific reaction of the patient and to define precisely his/her functional anatomy. Experience alone can improve the procedure. No maximal effect should then be sought on the first sitting.
On the injection days the patient is not required to fast.
Women should come without any make up or the same will have to be removed before the injections.
In order to reduce the pain caused by the injections, some “Emla” cream may be applied on the projected injection sites one hour prior to procedure. Such application can be repeated every 15 to 20 minutes to obtain some degree of local anaesthesia.
Before the injections, the following contraindications should be taken into account:
– Botulinum toxin is contraindicated in cases of recognized hypersensitivity to Botulinum A neurotoxin, myasthenia gravis and Lambert Eaton’s syndrome, and is absolutely not recommended during pregnancy and aminoside-based therapy (a type of antibiotic), like Amiklin, Gentalline,…
– In case of pregnancy of even only a few days’ duration, the injection date must be postponed until after the pregnancy and the breast-feeding period, as the case may be. Therefore, in case of any doubt you should undergo the appropriate tests and let us know the results.
It is also important to respect a certain number of precautions:
Significant ecchymoses may develop that can lead to the toxin spreading to unwanted sites during the resorption phase. It is very important, therefore, to minimise the risk of bleeding in the areas treated by avoiding taking aspirin (or any aspirin derivative) for 15 days before and 15 days after the injections. Paracetamol is allowed, however.
If you are treated with botulinum toxin for pathological spasms, if you have suffered from facial muscle paralysis, if you suffer from any neuromuscular illness or coagulation disorder, you should inform Dr LE LOUARN who, together with your physician, will assess the suitability of the planned injections and the best way in which to proceed with those if appropriate.
If, prior to an injection session, you are taking anticoagulant medicines or aspirin or antibiotics, or if you have any health problem (especially an infection, the flu, a dental abscess, etc) it is imperative that you inform Dr LE LOUARN before the injection.
As a rule, you should inform Dr LE LOUARN of the slightest health problems so that he can assess whether he should go ahead with the injections, and you should not hesitate to ask any question you may have. You should also tell him about all the treatments you have undergone and / or are still undergoing.
The injections should be administered at least 7 to 15 times at 3/7 month intervals to obtain some result stability. It is recommended never to repeat injections less than 3 months after the previous session, namely in order to prevent resistance to the product from building up, i.e., the so-called “vaccine effect”.
During the two hours after the injections, you should neither practise intensive sport, nor lie down. You should also avoid touching violently your face (or pressed massages) for 24 hours after the session to avoid traumatising injected tissues (risk of product migration).
On the other hand, during the 3 days after the injection, the injected muscles should be tightly contracted for 5 seconds in order to promote product fixation within the treated areas. It is precisely the movement that we want to reduce that will be performed.
It is necessary to minimise the risks of bruising or bleeding in the treated areas during the days following the injections (to limit the risk of the product leaking towards the periphery muscles and, hence, of unwanted effects).
When the eye contour is injected, eye dryness may occur. If significant and not treated, this could cause keratitis. Therefore, it is best to put artificial tears into the eyes, especially for patients who wear contact lenses.
If desired, an additional, and very highly localized injection of botulinum toxin may be used in the period between 20 days and one month following the injection to adjust result. The same must not be carried out before the 20 th day since effects may vary over these first 20 days. This additional injection can only be used on an exceptional and limited basis in order not to induce any vaccine-effect.
Some rare untoward effects may occur, such as:
• Ecchymoses :
Seldom, bruises can be observed in the injected areas. To minimise this problem, oral administration of Arnica may be started 5 days before the injection session.
• Oedemas :
Exceptionally, a swelling around the eyes can appear a few days after the injections. This swelling disappears spontaneously after 5 to 10 days.
• Fatigue :
During the 2–3 days after the injection.
After the injections, do not hesitate to contact your physician if you have any concerns.
Nowadays, known local or general complications are very rare. To these risks must the unpredictability of durability and aspect as well as the e xceptional or even unknown risks inherent to any medical procedure.
These complications are annoying but they disappear after a few weeks:
– Headaches : Unpredictable, they generally disappear after a few days. It should be noted that certain patients who usually suffer from migraine headaches notice, on the contrary, a frank improvement of their condition.
– Eyebrow drooping : The injection into the lower half of the forehead to act against low horizontal forehead wrinkles can lead to some drooping of the eyebrows. This returns to normal within a few weeks. Therefore, in certain patients it is judged best not to treat those low frontal wrinkles.
– Drooping of the eyelids : The injection into lion’s wrinkles can cause one of the upper eyelids to droop. This problem is rare (less than 1% of cases) and always disappears after a few weeks.
– Difficulty of speech : Injections to counter the vertical lines around the mouth can cause transient speech difficulty.
– Difficulty on swallowing : The injection at the angle of the neck and the chin to treat the cervical bands can lead to transient difficulty on swallowing.
These complications are quite exceptional. They are listed by the laboratory as follows:
• Allergic reactions: skin eruption, urticariae, general allergic reactions.
• Nausea and / or vertigo.
• Fever, or even flu syndrome.
Cosmetic surgery aims at making people happier. Some times, however, it may happen that the expected effect is not reached and that such surgery, on the contrary, enhances pre-existing psychological disturbances. The “post-injection” experience may differ drastically from one patient to the next even though the aesthetic results compare. As far as botulinum toxin is concerned, the rejuvenation effect is most often obtained at the expense of some of the face expressions. This aspect should be weighed so as to avoid disappointments, especially if you are an actor, an announcer…
The results will be visible after a few days, but for approximately two weeks, the effects on the face can vary (even be asymmetric at certain moments) before stabilising. During the first sessions, the positive effects usually disappear after 3 to 6 months.
Since the product acts on muscle tone and on skin hydration, different effects can be obtained not only on two different patients, but even on the same patient from one session to the next. Moreover, due to the particularity of the manufacture of the toxin, there can be a difference in the concentration of the product of up to 20% from one bottle to the other.
Repeat treatment sessions allow for a finer analysis of the results obtained and, hence, for optimizing those at each consecutive session, as well as optimizing the anti-age effect in time. It is quite obvious that this is conceivable only if both the patient and surgeon cooperate actively in the process.
The patient must participate in the process:
• by respecting the visiting schedule and not coming too early or too late! It is absolutely unthinkable to return after 4 months, saying that “this hasn’t worked” or that “it was not right the last time” because if the practitioner has not seen the effect at one month’s interval, he/she cannot adjust the injections. It is as unreasonable, also, to want systematic corrections (vaccine effect) or premature ones (within 20 days of the injection).
• by avoiding having treatment sessions here and there, thereby not allowing for long-term optimization.
• by accepting effect variations compatible with the product’s intrinsic variations.
The surgeon must:
• not be content with injecting the patient repeatedly but re-analyse the latter’s face expression at each sitting, the results already obtained in the past and the end result sought, and he/she should adjust the injections consequently. For example, in the course of the different sessions, he/she must detect a possible transfer of activity from one muscle to another. A patient may, for instance, strongly lower the corner of his/her mouth by using his/her DAO and, after a few sessions, use his/her platysma muscle instead, as the DAO is no longer used to working. Obviously, the practitioner will have to take such an evolution of the face expression into account when planning the following sessions.
• See the patient whose results are disappointing in order to understand the problem, analyse the cause (an external one, for instance, like a bruise causing product migration, product variation yielding an outcome less satisfactory than usual, a diminished effect in the patient, a non-optimal selection during the previous session), explain and even adjust the oncoming sessions.
Although the injection of botulinum toxin is a very technical procedure it is not an exact science that can be reproduced (neither from one patient to the next nor on the same patient from one sitting to the next). No perfection is to be expected, but improved looks in the short term and an anti-age effect in the long term can be.
Botulinum toxin injections should be administered by a trained practitioner who can clearly inform you of all possible benefits and risks, who guarantees the traceability of the product injected and who performs the injections by adapting them to the anatomic specificities of each patient. The patient must fully participate, both in the assessment of desired results and by respecting the pre- and post-injection recommendations.
Some information is available in French regarding botulinum toxin injections for aesthetic purpose, please refer to page « La Toxine Botulique » on the SOFCPRE’s website (Société Française de Chirurgie Plastique Reconstructrice et Esthétique) :
Specific informations appearing on this website are based on Doctor Le Louarn’s practice and on his scientific works :
1 – LE LOUARN C : Toxine botulique et Face Recurve® : action sur le tonus de repos et la régénération musculaire – Botulinum toxin and the Face Recurve® concept : decreasing resting tone and muscular regeneration
Ann Chir Plast Esthet. 2007 Jun;52(3):165-76.
2 – LE LOUARN C. : Facial lines and wrinkles due muscle hyperkynesia
Chapter in the work of D. Ranoux and C. Gury, entitled « Practical Handbook on Botulinum Toxin »,
SOLAL Marseille publisher 2006 : 231-236
3 – LE LOUARN C. : Toxine botulique à visée esthétique et analyse fonctionnelle de la Face
Chapître dans l’ouvrage du Professeur Raymond Gola, intitulé « Chirurgie esthétique et fonctionnelle de la face »
Springler-Verlag France, Paris, 2005 (ISBN2-287-21183-7)
4 – LE LOUARN C. : Analyse fonctionnelle de l’injection de toxine botulique à visée esthétique – Functional facial analysis after botulinum toxin injection
Ann Chir Plast Esthet. 2004 Oct;49(5):527-36.
5 – LE LOUARN C. : Rides Faciales dues à l’hyperkinésie musculaire
Chapître dans l’ouvrage des Docteurs D. Ranoux et C. Gury, intitulé « Manuel d’utilisation de la toxine botulique »
éditions SOLAL Marseille 2002 : 245-60
6 – LE LOUARN C. : Botulinum toxin A and facial lines: the variable concentration
Aesthetic Plast Surg. 2001 Mar-Apr;25(2):73-84. PMID: 11349306 [PubMed – indexed for MEDLINE]
7 – LE LOUARN C. : Toxine Botulique et rides faciales : une nouvelle procédure d’injection
Botulinum toxin and facial wrinkles: a new injection procedure
Ann Chir. Plast. Esthet.1998 Oct ; 43(5):526-33.
In this field, the following publications and works can also be listed ( this list is obviously not exhaustive and may be amended) :
1 – CARRUTHERS J.D., CARRUTHERS J.A. : Treatment of glabellar frown lines with C. botulinum A exotoxin
J Dermatol Surg Oncol. 1992 Jan;18(1):17-21
The idea of using « myorelaxing » properties of botulinum toxin for facial rejuvenation purposes is due to Doctors Jean and Alastair Carruthers
2 – ASCHER B., ZAKINE B., KESTEMONT P., BASPEYRAS M., BOUGARA A., SANTINI J. : A multicenter, randomized, double-blind, placebo-controlled study of efficacy and safety of 3 doses of botulinum toxin A in the treatment of glabellar lines
J Am Acad Dermatol. 2004 Aug;51(2):223-33
3 – BELHAOUARI L., GASSIA V., LAUWERS F. : Balance musculaire frontale et toxine botulique – Frontal muscular balance and botulinum toxin
Ann Chir Plast Esthet. 2004 Oct ; 49(5):521-6
4 – ASCHER B., BELHAOUARI L., LE LOUARN C. et coll : « La toxine botulique »
Section 4 dans : « Le rajeunissement facial : techniques de complément et de substitution à la chirurgie »
49ème Congrès national de la SOF.CPRE (rapport annuel) sous la présidence du Pr M. PANNIER:
Ann Chir Plast Esthet. 2004 (5)
5 – DE MAIO M. : Botulinum toxin in association with other rejuvenation methods
J Cosmet Laser Ther. 2003 Dec ; 5(3-4):210-2