Injection Techniques with Botulinum Toxin A in the Treatment of Blepharospasm

By
Mark Stacy, M.D.
Director, Muhammad Ali Parkinson Center and
Movement Disorder Clinic
Barrow Neurological Institute
Phoenix, Arizona

The development of Botulinum toxin, a muscle paralyzing agent from the bacteria, Clostridium botulinum, has produced major advances in the treatment of dystonia (such as blepharospasm or torticollis), hemifacial spasm, tremor, tic disorders, and a variety of other conditions - including those annoying crow's feet! Because such a wide range of injection techniques are used in treating blepharospasm, a group of ophthalmologists and neurologists recognized as "experts" by the BEBRF were surveyed for injection location, and the amount of toxin injected on the initial visit. The purpose of this highly unscientific survey was not to determine the "best" approach to treat any individual, but to provide the reader with some understanding of the number and location of injections at each visit, and to quantify the amount of toxin that was given at a typical office visit. Each of the respondents were asked to list typical dosages, dilution, and number of injections for an imaginary patient. Remember that clinical judgment at each patient encounter will vary any of these data.

Each physician was mailed a diagram (see below) and asked to mark each injection site, units of toxin injected per site (initially and on average), and the dilution factor for the toxin. Of the eight respondents, 5 clinicians always diluted the toxin at a rate of 100 units (1 vial) per milliliter. One respondent used this dilution for dosages greater than 5 units per injection, but would dilute to a concentration of 100 units (1 vial) per 2 milliliters for smaller dosages. This will allow for more diffusion around the injection site, presumably providing a more even effect. Conversely, in instances where side effects, such as lid drooping (ptosis), double vision (diplopia), or tearing occurs, injection with less diluted toxin (100 units in 1/2 milliliter) may allow more effective response without these side effects. Two physicians did not indicate their dilution factor. Dosages varied per respondent in terms of injection site and total dose, On average, the total dosage ranged from 30 - 60 units (15-30 units per eye). This average range did not differ from the initial dosage, but all responders indicated that a gradual increase in the dose is necessary to gain optimum benefit in many patients. Dosage per site was most often 5 units, with two clinicians using 2.5 and another using 7.5 unit doses. [See table]

  Total Dosage Dilution Number of injections
Neurologist      
1 50 units 100 units/ml 10
2 50 units 100 units/ml 12
3 60 units 50 units/ml 12
4 60 units 100 units/ml 10
Ophthalmologist      
1 50 units   10
2 50 units 100 units/ml 9
3 50 units   12
4 30 units 100 units/ml 12

Injection locations varied between these clinicians, but were more consistent among neurologists. The number of injections per visit varied from 9 to 12. with 5 of the 8 respondents injecting each patient 10 times. All physicians injected the frontalis muscles (above the eyebrow); upper lids and lower lids. Two neurologists and one ophthalmologist injected lateral to each eye. Among ophthalmologists, upper lid injections were divided equally between injection on the lid and higher in the fold of the upper lid, while all neurologists injected on the lid. [See diagrams]

Injection site diagram

In summary, the physicians selected to participate in this survey were recommended from the BEBRF, and loosely represent every geographic location in the country Although some variability exists between injection location choices between the respondents, the number of injections and dosages are highly consistent. The treatment of blepharospasm involves science, art and good communication between a patient and clinician. With improved understanding of injection approach. communication will also improve, and hopefully, a better result for the patient.

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