- Email: [email protected]
The Use of Botox® in Interventional Radiology
The Use of Botox® in Interventional Radiology John D. Bennett, MDCM, FRCPC,* Thomas A. Miller, MD, FRCPC,† and Robert S. Richards, MD, FRCSC‡ Botox® (Botulinum toxin A) has wide public recognition as a cosmetic agent. It has also established a firm foothold within the medical community for the treatment of a wide range of myospastic disorders. With imaging guidance, interventional radiologists can deliver this medication to a variety of otherwise difficult to reach targets with high accuracy and with minimal complications. We illustrate the use of Botox® in interventional radiology by describing our fluoroscopic technique for the treatment of piriformis syndrome. The key to successful Botox® therapy of myospastic disorders is accurate clinical diagnosis. Excellent communication and rapport with the referring clinicians is therefore essential to maximize the likelihood of a successful outcome. The range of services offered by interventional radiologists continues to evolve. With the recent growth of endovenous treatment for varicose veins, some have found it necessary to provide sclerotherapy for spider veins. As patients become accustomed to receiving these cosmetic treatments from interventionalists, they may come to us for advice about other esthetic therapy. The idea of some interventional radiologists adding cosmetic medicine to their practice should, therefore, not seem unreasonable. We illustrate the use of Botox® for facial rejuvenation by describing our technique for the treatment of glabelar (frown) lines. Before entering into this type of practice, it is critical to obtain adequate and appropriate training for each cosmetic intervention. If possible, the interventionalist should seek to establish a mentor relationship with someone highly experienced in cosmetic medicine. Tech Vasc Interventional Rad 9:36-39 © 2006 Elsevier Inc. All rights reserved. KEYWORDS botulinum toxin, piriformis syndrome, facial rejuvenation
B
otulinum Toxin Type A is a 150-kD single-chain polypeptide produced by Clostridium Botulinum and its existence has been known for centuries. However, its utility as an injectable therapeutic agent was only first suspected in the late 1970s and early 1980s.1 In 1989, the Food and Drug Administration (FDA) approved its use for the treatment of strabismus, blepharospasm, and hemifacial spasm. Interest in Botulinum Toxin as a therapeutic agent has increased over time and truly exploded since the turn of the last century. A title search of “Botulinum Toxin” in PubMed reveals over 250 peer-reviewed articles published in core medical journals since the year 2000. The current FDA approved uses for Botulinum Toxin include the following: temporary improvement in the appearance of moderate to severe glabelar lines, blepharospasm, cervical dystonia, severe primary axillary hyperhidrosis, and strabismus. All other applications constitute “off label” use in the United States.
*CML Health Care Inc., London, Ontario, Canada. †Department Of Physical Medicine and Rehabilitation, ‡Department of Surgery, Division of Plastic Surgery, University of Western Ontario Schulich School Of Medicine and Dentistry, St. Joseph’s Health Care, London, Ontario, Canada. Address reprint requests to John D. Bennett, MDCM, FRCPC, CML Health Care Inc., 279 Wharncliffe Rd. North Unit 111, London, Ontario, Canada, N6H 2C2. E-mail: [email protected].
36
1089-2516/06/$-see front matter © 2006 Elsevier Inc. All rights reserved. doi:10.1053/j.tvir.2006.08.008
The mechanism of action for Botulinum Toxin is through the inhibition of acetylcholine release from presynaptic neurons at the neuromuscular junction. This permanently disables the motor end plate and leads to functional denervation of the muscle.2 Muscle weakness typically becomes apparent over 3 to 10 days with an anticipated duration of effect ranging from 3 to 6 months. The neuromuscular junction recovers by presynaptic axonal “resprouting” resulting in the formation of new motor end plates and, in effect “re-innervation” of the muscle.3 Botulinum Toxin (Botox®) is supplied in a vial containing 100 U of vacuum-dried Clostridium Botulinum Type A neurotoxin complex. Unreconstituted, Botox® can be kept frozen for 2 years. We use preserved normal saline to reconstitute Botox®. Once reconstituted, the manufacturer recommends that it be used within 4 hours; however, some studies have suggested that once reconstituted, Botox® may be frozen, rethawed before injection, and retain its potency for up to 2 weeks.4
Image-Guided Botulinum Toxin for Piriformis Syndrome The piriformis muscle is a triangular muscle arising from the ventral aspect of the sacrum. It passes through the greater
Botox® in interventional radiology
Figure 1 Schematic representation of the trajectory of the piriformis muscle. The posterior fluoroscopic landmark for piriformis injection is marked (A).
sciatic foramen to insert on the anteromedial aspect of the greater trochanter of the femur. The sciatic nerve is closely related to the anterior surface of the piriformis and may occasionally pass through a slit in the muscle belly before descending posteriorly in the thigh. Piriformis syndrome is characterized by symptoms and signs thought to arise from sciatic nerve irritation and entrapment at the greater sciatic notch by the piriformis muscle.5 Some consider it to be an under-diagnosed form of buttock and leg pain often mimicking and mistaken for other causes of sciatica.6-8 It is clinically characterized by gluteal pain, sciatica and often exacerbated by walking and sitting (even for short periods of time). Reproduction of symptoms on deep gluteal, transrectal, or transvaginal palpation of the piriformis is felt to be highly suggestive of this diagnosis.5 Additional supportive findings on physical examination include weakened abduction of the flexed thigh and a positive straight leg raise test. To perform a straight leg raise test, the patient should be supine and then flex the hip while maintaining the knee in an extended position. Electromyography and imaging are primarily useful in excluding other causes of sciatica although hypertrophy of the piriformis muscle as demonstrated on computed tomography scans and magnetic resonance imaging has been described in association with this syndrome.9 A variety of therapeutic options are available for the management of piriformis syndrome, ranging from surgical division of the piriformis muscle5 to minimally invasive tech-
37 niques to physiotherapy10-13 to oral, nonsteroidal anti-inflammatory medications, muscle relaxants, or both. A number of studies have demonstrated that injection of Botulinum Toxin into the piriformis muscle can be an effective treatment for this disorder.7,10-13 Injection of the piriformis muscle can be performed without imaging or electromyography; however, the use of imaging guidance should increase the likelihood of accurate needle placement. While some have used computed tomography,7 we have found fluoroscopic guidance to be rapid, accessible and very effective. For fluoroscopic injection of the piriformis, we place the patient prone on a fluoroscopic table. The posterior fluoroscopic landmark for injection is approximately one centimeter above the junction of the middle and medial thirds of the superior acetabular rim (see Fig. 1). After skin preparation and draping, a 25g spinal needle is advanced until it comes into contact with the posterior ilium. Occasionally, a tactile “pop” can be perceived as the needle passes through the posterior piriformis fascia. Once the needle tip contacts bone, it is withdrawn 5 to 10 mm. At this point, 1 to 2 mL of nonionic contrast diluted one-to-one with local anesthetic is injected. The contrast assumes a characteristic and easily recognizable pattern as it spreads along the piriformis muscle fibers (see Fig. 2). If this pattern is not visible, the needle is not within the muscle belly and must be repositioned. When this happens, redirecting the needle slightly more toward the midline can increase the chances of entering the muscle belly (because it widens and thickens as it travels medially). For piriformis injections, we reconstitute 100 units of Botox® in 5 mL of preserved normal saline and generally inject between 50 and 100 units per side. As the unopacified Botox® solution is injected, contrast within the piriformis can be seen to dilute and spread that confirms accurate delivery of the med-
Figure 2 Contrast has been injected revealing the characteristic pattern as it spreads along the piriformis muscle fibers.
38
Figure 3 Detailed view of the glabelum of a female patient (frowning). The numbers indicate the typical Botox® unit dose distribution. The letters indicate the target muscle. C, corrugator supercilli; P, procerus. Most female patients will require between 15 and 20 units to treat the glabelum. Males and females with large corrugators will typically require more.
ication. After injection, the onset of muscle weakness generally occurs in 3 to 4 days with the full effect apparent within 10 to 14 days. At this point, the patient may begin physiotherapy and stretching exercises aimed at lengthening the piriformis. Muscle relaxation can be expected to last for 2 to 6 months. The key to successful therapy of piriformis syndrome is accurate clinical diagnosis. There are few technical limitations to image-guided delivery Botox® into this (or almost any) muscle. However, the correct diagnosis must be established before treatment with Botox® is initiated. It is therefore essential that the interventional radiologist develop excellent communication and rapport with the referring clinician. With accurate diagnosis and good technique, fair to excellent response can be obtained in 90% of patients.13 Other sites for which we have used imaging guidance for therapeutic injection of Botox® include psoas, paraspinal muscles, iliacus, rectus abdominus, scalenes, and quadratus lumborum. A detailed discussion of these techniques is beyond the scope of this article.
Botulinum Toxin for Facial Rejuvenation The thought of interventionalists performing cosmetic medical procedures will, no doubt, raise a few eyebrows. Interventional radiology has been evolving rapidly since its recognition as a subspecialty. As technology has advanced, we have continually pushed the boundaries and successfully entered, and contributed substantially to, areas previously considered the domain of other specialists. The recent growth of image-guided treatment for varicose veins has prompted many interventional radiologists to provide sclerotherapy for spider veins. The rapport developed between these patients and their physician leads to the development of trust, potentially resulting in consultations for advice about other cosmetic treatments. With this in mind, the concept of some interventionalists adding cosmetic medicine to their armamentarium should not seem unreasonable. Interventional radiologists (like all imagers) are visually orientated and should have the manual dexterity to carry out these procedures without too much difficulty. It is, however,
J.D. Bennett, T.A. Miller, and R.S. Richards critical to obtain adequate and appropriate training for each cosmetic intervention. A thorough understanding of facial muscular anatomy as well as the dynamics of facial expression is essential. While not always feasible, it is also desirable to establish a mentor relationship with someone highly experienced in cosmetic medicine. As with all aspects of medicine, continuing medical education and training are essential to remain current and provide the best service to our patients. The use of Botox® for facial rejuvenation has been FDA approved since 2002.14 For illustrative purposes, we will describe our technique for the treatment of frown lines (glabelar lines). There are innumerable chemodenervation protocols for facial rejuvenation available.15-18 An exhaustive review of the many uses of Botox® in facial rejuvenation is beyond the scope of this article. For cosmetic purposes, we reconstitute 100 units of Botox® in 4 mL of preserved normal saline. This produces a solution with a concentration of 2.5 units per 0.1 mL. The solution is then drawn up into 1 mL insulin syringes. Because of the extremely small volumes being injected, 0.5 or 1 mL syringes are necessary to provide the control required for accurate dosing. At this concentration, a volume of 0.04 mL represents each unit of Botox®. Glabelar lines primarily result from contraction of the corrugator supercilli and procerus muscles. These two muscles therefore serve as the targets for chemodenervation. The corrugator muscle bellies are easily palpated with the patient frowning. Between 5 and 7.5 units of Botox® are then injected at two or three sites within the muscle on each side, depending on its configuration (Figs. 3 and 4). With normal anatomic variation, the injection pattern may differ between patients. The procerus muscle, while more difficult to palpate, is easily targeted on either side of the nasal bone at the level of the bridge of the nose. Between 2 to 2.5 units are typically injected on either side. Female patients typically require between 15 to 20 units of Botox® to adequately treat the corrugator and procerus muscles. Male patients and females with large corrugators often require larger doses. Once the injections are completed, pressure is applied to the target sites for 5 to 10 minutes to minimize bruising. Ice packs and cold compresses can also be used. Patients are advised that the full effect may not be evident for 10 to 14 days. It is helpful to have patients return after 2 weeks so that the re-
Figure 4 Detailed view of the glabelum of the same female patient as in Fig. 3 (still frowning) showing a marked reduction in the glabelar lines 2 weeks after the injection of 18 units of Botox®. The patient now has a more rested and less worried “look”.
Botox® in interventional radiology sults can be assessed. If necessary, supplemental injections can be performed to achieve the desired result. Complications from facial Botox® injections are rare. The most common adverse consequences are lack of effect, injection site reaction, and the rare risk of eyelid ptosis if Botox® diffuses into the orbit.14 The protocol we have developed uses a more dilute Botox® concentration than many and also tends toward lower doses. We feel that this offers two advantages. It is generally thought that adverse effects from Botox® are directly related to dosage.14 Lower doses should therefore be associated with a decreased incidence of adverse effect. Lower doses also result in diminished cost to the patient. With good technique, precision, and attention to detail, we feel that we can obtain equivalent cosmetic results, with less risk and at a lower cost to the patient. Obviously, not every interventional radiologist should or would want to enter into cosmetic medicine. This option might be more suitable for those in private practices, which already include varicose vein treatment and sclerotherapy. This type of work also requires that the clinician be comfortable and happy dealing with a clientele who are detail oriented and, on occasion, can be quite demanding. It is critical that any interventional radiologist entering this field is committed to excellence. As early entrants into this realm we represent our subspecialty and should be committed to upholding the reputation of interventional radiologists as contributors, leaders, and innovators.
References 1. Frueh BR, Felt DP, Wojno TH, et al: Treatment of blepharospasm with botulinum toxin. A preliminary report. Arch Ophthalmol 102:14641468, 1984 2. Montecucco C, Schiavo G: Mechanism of action of tetanus and botulinum neurotoxins. Mol Microbiol 13:1-8, 1994 3. Duchen LW, Strich S: The effects of botulinum toxin on the pattern of innervation of skeletal muscle in the mouse. Q J Exp Physiol Cogn Med Sci 53:8-89, 1968
39 4. Jabor MA, Kaushik R, Shayani P, et al: Efficacy of reconstituted and stored botulinum toxin type A: An electrophysiologic and visual study in the auricular muscle of the rabbit. Plast Reconstr Surg 111:24192426, 2003 5. Solheim LF, Siewers P, Paus B: The piriformis muscle syndrome. Sciatic nerve entrapment treated with section of the piriformis muscle. Acta Orthop Scand 52:73-75, 1981 6. Durrani Z, Winnie AP: Piriformis muscle syndrome: An underdiagnosed cause of sciatica. J Pain Symptom Manage 6:374-379, 1991 7. Fanucci E, Masala S, Sodani G, et al: CT-guided injection of botulinic toxin for percutaneous therapy of piriformis muscle syndrome with preliminary MRI results about denervative process. Eur Radiol 11: 2543-2548, 2001 8. Barton PM: Piriformis syndrome: A rational approach to management. Pain 47:345-352, 1991 9. Jankiewicz JJ, Hennrikus WL, Houkom JA: The appearance of the piriformis muscle syndrome in computed tomography and magnetic resonance imaging. A case report and review of the literature. Clin Orthop Relat Res 262:205-209, 1991 10. Fishman SM, Caneris OA, Bandman TB, et al: Injection of the piriformis muscle by fluoroscopic and electromyographic guidance. Reg Anesth Pain Med 23:554-559, 1998 11. Childers MK, Wilson DJ, Gnatz SM, et al: Botulinum toxin type A use in piriformis muscle syndrome: A pilot study. Am J Phys Med Rehabil 81:751-759, 2002 12. Fishman LM, Anderson C, Rosner B: Botox® and physical therapy in the treatment of piriformis syndrome. J Phys Med Rehabil 81:936-942, 2002 13. Lang AM: Botulinum toxin type B in piriformis syndrome. Am J Phys Med Rehabil 83:198-202, 2004 14. Cote TR, Mohan AK, Polder JA, et al: Botulinum toxin type A injections: Adverse events reported to the US Food and Drug Administration in therapeutic and cosmetic cases. J Am Acad Dermatol 53:407-415, 2005 15. Andrew C: Markey: Botulinum A exotoxin in cosmetic dermatology. Clin Exp Dermatol 25:173-175, 2000 16. Hankins CL, Strimling R, Rogers GS: Botulinum A toxin for glabellar wrinkles. Dose and response. Dermatol Surg 24:1181-1183, 1998 17. Goodman G: Botulinum toxin for the correction of hyperkinetic facial lines. Australas J Dermatol 39:158-163, 1998 18. Carruthers A, Carruthers J, Cohen J: A prospective, double-blind, randomized, parallel- group, dose-ranging study of botulinum toxin type a in female subjects with horizontal forehead rhytides. Dermatol Surg 29:461-467, 2003
B
otulinum Toxin Type A is a 150-kD single-chain polypeptide produced by Clostridium Botulinum and its existence has been known for centuries. However, its utility as an injectable therapeutic agent was only first suspected in the late 1970s and early 1980s.1 In 1989, the Food and Drug Administration (FDA) approved its use for the treatment of strabismus, blepharospasm, and hemifacial spasm. Interest in Botulinum Toxin as a therapeutic agent has increased over time and truly exploded since the turn of the last century. A title search of “Botulinum Toxin” in PubMed reveals over 250 peer-reviewed articles published in core medical journals since the year 2000. The current FDA approved uses for Botulinum Toxin include the following: temporary improvement in the appearance of moderate to severe glabelar lines, blepharospasm, cervical dystonia, severe primary axillary hyperhidrosis, and strabismus. All other applications constitute “off label” use in the United States.
*CML Health Care Inc., London, Ontario, Canada. †Department Of Physical Medicine and Rehabilitation, ‡Department of Surgery, Division of Plastic Surgery, University of Western Ontario Schulich School Of Medicine and Dentistry, St. Joseph’s Health Care, London, Ontario, Canada. Address reprint requests to John D. Bennett, MDCM, FRCPC, CML Health Care Inc., 279 Wharncliffe Rd. North Unit 111, London, Ontario, Canada, N6H 2C2. E-mail: [email protected].
36
1089-2516/06/$-see front matter © 2006 Elsevier Inc. All rights reserved. doi:10.1053/j.tvir.2006.08.008
The mechanism of action for Botulinum Toxin is through the inhibition of acetylcholine release from presynaptic neurons at the neuromuscular junction. This permanently disables the motor end plate and leads to functional denervation of the muscle.2 Muscle weakness typically becomes apparent over 3 to 10 days with an anticipated duration of effect ranging from 3 to 6 months. The neuromuscular junction recovers by presynaptic axonal “resprouting” resulting in the formation of new motor end plates and, in effect “re-innervation” of the muscle.3 Botulinum Toxin (Botox®) is supplied in a vial containing 100 U of vacuum-dried Clostridium Botulinum Type A neurotoxin complex. Unreconstituted, Botox® can be kept frozen for 2 years. We use preserved normal saline to reconstitute Botox®. Once reconstituted, the manufacturer recommends that it be used within 4 hours; however, some studies have suggested that once reconstituted, Botox® may be frozen, rethawed before injection, and retain its potency for up to 2 weeks.4
Image-Guided Botulinum Toxin for Piriformis Syndrome The piriformis muscle is a triangular muscle arising from the ventral aspect of the sacrum. It passes through the greater
Botox® in interventional radiology
Figure 1 Schematic representation of the trajectory of the piriformis muscle. The posterior fluoroscopic landmark for piriformis injection is marked (A).
sciatic foramen to insert on the anteromedial aspect of the greater trochanter of the femur. The sciatic nerve is closely related to the anterior surface of the piriformis and may occasionally pass through a slit in the muscle belly before descending posteriorly in the thigh. Piriformis syndrome is characterized by symptoms and signs thought to arise from sciatic nerve irritation and entrapment at the greater sciatic notch by the piriformis muscle.5 Some consider it to be an under-diagnosed form of buttock and leg pain often mimicking and mistaken for other causes of sciatica.6-8 It is clinically characterized by gluteal pain, sciatica and often exacerbated by walking and sitting (even for short periods of time). Reproduction of symptoms on deep gluteal, transrectal, or transvaginal palpation of the piriformis is felt to be highly suggestive of this diagnosis.5 Additional supportive findings on physical examination include weakened abduction of the flexed thigh and a positive straight leg raise test. To perform a straight leg raise test, the patient should be supine and then flex the hip while maintaining the knee in an extended position. Electromyography and imaging are primarily useful in excluding other causes of sciatica although hypertrophy of the piriformis muscle as demonstrated on computed tomography scans and magnetic resonance imaging has been described in association with this syndrome.9 A variety of therapeutic options are available for the management of piriformis syndrome, ranging from surgical division of the piriformis muscle5 to minimally invasive tech-
37 niques to physiotherapy10-13 to oral, nonsteroidal anti-inflammatory medications, muscle relaxants, or both. A number of studies have demonstrated that injection of Botulinum Toxin into the piriformis muscle can be an effective treatment for this disorder.7,10-13 Injection of the piriformis muscle can be performed without imaging or electromyography; however, the use of imaging guidance should increase the likelihood of accurate needle placement. While some have used computed tomography,7 we have found fluoroscopic guidance to be rapid, accessible and very effective. For fluoroscopic injection of the piriformis, we place the patient prone on a fluoroscopic table. The posterior fluoroscopic landmark for injection is approximately one centimeter above the junction of the middle and medial thirds of the superior acetabular rim (see Fig. 1). After skin preparation and draping, a 25g spinal needle is advanced until it comes into contact with the posterior ilium. Occasionally, a tactile “pop” can be perceived as the needle passes through the posterior piriformis fascia. Once the needle tip contacts bone, it is withdrawn 5 to 10 mm. At this point, 1 to 2 mL of nonionic contrast diluted one-to-one with local anesthetic is injected. The contrast assumes a characteristic and easily recognizable pattern as it spreads along the piriformis muscle fibers (see Fig. 2). If this pattern is not visible, the needle is not within the muscle belly and must be repositioned. When this happens, redirecting the needle slightly more toward the midline can increase the chances of entering the muscle belly (because it widens and thickens as it travels medially). For piriformis injections, we reconstitute 100 units of Botox® in 5 mL of preserved normal saline and generally inject between 50 and 100 units per side. As the unopacified Botox® solution is injected, contrast within the piriformis can be seen to dilute and spread that confirms accurate delivery of the med-
Figure 2 Contrast has been injected revealing the characteristic pattern as it spreads along the piriformis muscle fibers.
38
Figure 3 Detailed view of the glabelum of a female patient (frowning). The numbers indicate the typical Botox® unit dose distribution. The letters indicate the target muscle. C, corrugator supercilli; P, procerus. Most female patients will require between 15 and 20 units to treat the glabelum. Males and females with large corrugators will typically require more.
ication. After injection, the onset of muscle weakness generally occurs in 3 to 4 days with the full effect apparent within 10 to 14 days. At this point, the patient may begin physiotherapy and stretching exercises aimed at lengthening the piriformis. Muscle relaxation can be expected to last for 2 to 6 months. The key to successful therapy of piriformis syndrome is accurate clinical diagnosis. There are few technical limitations to image-guided delivery Botox® into this (or almost any) muscle. However, the correct diagnosis must be established before treatment with Botox® is initiated. It is therefore essential that the interventional radiologist develop excellent communication and rapport with the referring clinician. With accurate diagnosis and good technique, fair to excellent response can be obtained in 90% of patients.13 Other sites for which we have used imaging guidance for therapeutic injection of Botox® include psoas, paraspinal muscles, iliacus, rectus abdominus, scalenes, and quadratus lumborum. A detailed discussion of these techniques is beyond the scope of this article.
Botulinum Toxin for Facial Rejuvenation The thought of interventionalists performing cosmetic medical procedures will, no doubt, raise a few eyebrows. Interventional radiology has been evolving rapidly since its recognition as a subspecialty. As technology has advanced, we have continually pushed the boundaries and successfully entered, and contributed substantially to, areas previously considered the domain of other specialists. The recent growth of image-guided treatment for varicose veins has prompted many interventional radiologists to provide sclerotherapy for spider veins. The rapport developed between these patients and their physician leads to the development of trust, potentially resulting in consultations for advice about other cosmetic treatments. With this in mind, the concept of some interventionalists adding cosmetic medicine to their armamentarium should not seem unreasonable. Interventional radiologists (like all imagers) are visually orientated and should have the manual dexterity to carry out these procedures without too much difficulty. It is, however,
J.D. Bennett, T.A. Miller, and R.S. Richards critical to obtain adequate and appropriate training for each cosmetic intervention. A thorough understanding of facial muscular anatomy as well as the dynamics of facial expression is essential. While not always feasible, it is also desirable to establish a mentor relationship with someone highly experienced in cosmetic medicine. As with all aspects of medicine, continuing medical education and training are essential to remain current and provide the best service to our patients. The use of Botox® for facial rejuvenation has been FDA approved since 2002.14 For illustrative purposes, we will describe our technique for the treatment of frown lines (glabelar lines). There are innumerable chemodenervation protocols for facial rejuvenation available.15-18 An exhaustive review of the many uses of Botox® in facial rejuvenation is beyond the scope of this article. For cosmetic purposes, we reconstitute 100 units of Botox® in 4 mL of preserved normal saline. This produces a solution with a concentration of 2.5 units per 0.1 mL. The solution is then drawn up into 1 mL insulin syringes. Because of the extremely small volumes being injected, 0.5 or 1 mL syringes are necessary to provide the control required for accurate dosing. At this concentration, a volume of 0.04 mL represents each unit of Botox®. Glabelar lines primarily result from contraction of the corrugator supercilli and procerus muscles. These two muscles therefore serve as the targets for chemodenervation. The corrugator muscle bellies are easily palpated with the patient frowning. Between 5 and 7.5 units of Botox® are then injected at two or three sites within the muscle on each side, depending on its configuration (Figs. 3 and 4). With normal anatomic variation, the injection pattern may differ between patients. The procerus muscle, while more difficult to palpate, is easily targeted on either side of the nasal bone at the level of the bridge of the nose. Between 2 to 2.5 units are typically injected on either side. Female patients typically require between 15 to 20 units of Botox® to adequately treat the corrugator and procerus muscles. Male patients and females with large corrugators often require larger doses. Once the injections are completed, pressure is applied to the target sites for 5 to 10 minutes to minimize bruising. Ice packs and cold compresses can also be used. Patients are advised that the full effect may not be evident for 10 to 14 days. It is helpful to have patients return after 2 weeks so that the re-
Figure 4 Detailed view of the glabelum of the same female patient as in Fig. 3 (still frowning) showing a marked reduction in the glabelar lines 2 weeks after the injection of 18 units of Botox®. The patient now has a more rested and less worried “look”.
Botox® in interventional radiology sults can be assessed. If necessary, supplemental injections can be performed to achieve the desired result. Complications from facial Botox® injections are rare. The most common adverse consequences are lack of effect, injection site reaction, and the rare risk of eyelid ptosis if Botox® diffuses into the orbit.14 The protocol we have developed uses a more dilute Botox® concentration than many and also tends toward lower doses. We feel that this offers two advantages. It is generally thought that adverse effects from Botox® are directly related to dosage.14 Lower doses should therefore be associated with a decreased incidence of adverse effect. Lower doses also result in diminished cost to the patient. With good technique, precision, and attention to detail, we feel that we can obtain equivalent cosmetic results, with less risk and at a lower cost to the patient. Obviously, not every interventional radiologist should or would want to enter into cosmetic medicine. This option might be more suitable for those in private practices, which already include varicose vein treatment and sclerotherapy. This type of work also requires that the clinician be comfortable and happy dealing with a clientele who are detail oriented and, on occasion, can be quite demanding. It is critical that any interventional radiologist entering this field is committed to excellence. As early entrants into this realm we represent our subspecialty and should be committed to upholding the reputation of interventional radiologists as contributors, leaders, and innovators.
References 1. Frueh BR, Felt DP, Wojno TH, et al: Treatment of blepharospasm with botulinum toxin. A preliminary report. Arch Ophthalmol 102:14641468, 1984 2. Montecucco C, Schiavo G: Mechanism of action of tetanus and botulinum neurotoxins. Mol Microbiol 13:1-8, 1994 3. Duchen LW, Strich S: The effects of botulinum toxin on the pattern of innervation of skeletal muscle in the mouse. Q J Exp Physiol Cogn Med Sci 53:8-89, 1968
39 4. Jabor MA, Kaushik R, Shayani P, et al: Efficacy of reconstituted and stored botulinum toxin type A: An electrophysiologic and visual study in the auricular muscle of the rabbit. Plast Reconstr Surg 111:24192426, 2003 5. Solheim LF, Siewers P, Paus B: The piriformis muscle syndrome. Sciatic nerve entrapment treated with section of the piriformis muscle. Acta Orthop Scand 52:73-75, 1981 6. Durrani Z, Winnie AP: Piriformis muscle syndrome: An underdiagnosed cause of sciatica. J Pain Symptom Manage 6:374-379, 1991 7. Fanucci E, Masala S, Sodani G, et al: CT-guided injection of botulinic toxin for percutaneous therapy of piriformis muscle syndrome with preliminary MRI results about denervative process. Eur Radiol 11: 2543-2548, 2001 8. Barton PM: Piriformis syndrome: A rational approach to management. Pain 47:345-352, 1991 9. Jankiewicz JJ, Hennrikus WL, Houkom JA: The appearance of the piriformis muscle syndrome in computed tomography and magnetic resonance imaging. A case report and review of the literature. Clin Orthop Relat Res 262:205-209, 1991 10. Fishman SM, Caneris OA, Bandman TB, et al: Injection of the piriformis muscle by fluoroscopic and electromyographic guidance. Reg Anesth Pain Med 23:554-559, 1998 11. Childers MK, Wilson DJ, Gnatz SM, et al: Botulinum toxin type A use in piriformis muscle syndrome: A pilot study. Am J Phys Med Rehabil 81:751-759, 2002 12. Fishman LM, Anderson C, Rosner B: Botox® and physical therapy in the treatment of piriformis syndrome. J Phys Med Rehabil 81:936-942, 2002 13. Lang AM: Botulinum toxin type B in piriformis syndrome. Am J Phys Med Rehabil 83:198-202, 2004 14. Cote TR, Mohan AK, Polder JA, et al: Botulinum toxin type A injections: Adverse events reported to the US Food and Drug Administration in therapeutic and cosmetic cases. J Am Acad Dermatol 53:407-415, 2005 15. Andrew C: Markey: Botulinum A exotoxin in cosmetic dermatology. Clin Exp Dermatol 25:173-175, 2000 16. Hankins CL, Strimling R, Rogers GS: Botulinum A toxin for glabellar wrinkles. Dose and response. Dermatol Surg 24:1181-1183, 1998 17. Goodman G: Botulinum toxin for the correction of hyperkinetic facial lines. Australas J Dermatol 39:158-163, 1998 18. Carruthers A, Carruthers J, Cohen J: A prospective, double-blind, randomized, parallel- group, dose-ranging study of botulinum toxin type a in female subjects with horizontal forehead rhytides. Dermatol Surg 29:461-467, 2003