Botulinum Toxin Type A for Frontal Hyperhidrosis

Primary focal hyperhidrosis is a chronic dermatological disorder characterized by excessive sweating due to overactivity of eccrine sweat glands. Frontal hyperhidrosis is a less common subtype; however, it has a significant psychological and social impact due to the visibility of symptoms and its effect on daily activities and quality of life.

Treatment options include topical antiperspirants such as aluminum chloride, systemic anticholinergic agents such as oxybutynin, and surgical sympathectomy. However, these modalities may be limited by insufficient efficacy or undesirable adverse effects, particularly in frontal hyperhidrosis.

Botulinum toxin type A is a neurotoxin produced by Clostridium botulinum that inhibits the release of acetylcholine at the neuromuscular and neuroglandular junctions, resulting in temporary suppression of eccrine sweat gland activity. Although it is widely used in axillary hyperhidrosis, evidence regarding its use in frontal hyperhidrosis remains limited.

Study Design and Procedures:

This is a prospective interventional clinical study conducted on patients diagnosed with primary frontal hyperhidrosis attending the dermatology clinic at Latakia University Hospital. Written informed consent will be obtained from all participants prior to enrollment.

A detailed medical history will be obtained to exclude patients with neuromuscular disorders, hypersensitivity to botulinum toxin or its components, and active local skin infections.

Baseline assessment of disease severity will be performed using the Hyperhidrosis Disease Severity Scale (HDSS).

The affected frontal area will be identified using Minor's iodine-starch test to confirm active sweating zones. The area will then be mapped into a grid of approximately 2.25 cm² squares with 1 cm spacing between injection points.

Botulinum toxin type A will be reconstituted with 5 ml of 0.9% sodium chloride solution to achieve a concentration of 20 units/ml. Intradermal injections of 2 units per grid point will be administered using a 30-gauge insulin needle.

The total dose will range between 40-80 units depending on the extent of the affected area.

Follow-up evaluation will be performed one month (4 weeks) after treatment.

Clinical outcomes will be assessed using:

* Hyperhidrosis Disease Severity Scale (HDSS)
* Minor's iodine-starch test for assessment of sweating area reduction
* Patient satisfaction questionnaire using a 5-point Likert scale
* Recording of any adverse effects or complications

Outcome measures will include reduction in sweating area, improvement in HDSS score, patient-reported satisfaction, and incidence of adverse events.

• Botulinum Toxin Type A (Drug): Botulinum toxin type A will be reconstituted with 5 mL of 0.9% sodium chloride solution to achieve a concentration of 20 units/mL. Intradermal injections of 2 units per injection point will be administered using a 30-gauge insulin needle. The affected frontal area will be mapped using Minor's iodine-starch test and divided into a grid of approximately 2.25 cm² squares with 1 cm spacing between injection points. The total dose will range from 40 to 80 units depending on the extent of the affected area.

Primary outcomes

• Change in Hyperhidrosis Disease Severity Scale (HDSS) score [Baseline and 1 month (4 weeks) after treatment]: Assessment of the change in severity of frontal hyperhidrosis using the Hyperhidrosis Disease Severity Scale (HDSS), a 4-point patient-reported scale. The score will be recorded at baseline prior to treatment and compared to the post-treatment score following intradermal Botulinum toxin type A injection. A reduction in score indicates clinical improvement in disease severity
• Change in hyperhidrotic area assessed by Minor's iodine-starch test [Baseline and 1 month (4 weeks) after treatment]: Assessment of changes in the frontal hyperhidrotic area using Minor's iodine-starch test. The affected area will be evaluated at baseline prior to treatment and compared with the post-treatment area following intradermal injection of botulinum toxin type A. Reduction in the stained area indicates decreased eccrine sweat gland activity

Secondary outcomes

• Patient satisfaction with clinical outcomes of intradermal botulinum toxin type A treatment in primary frontal hyperhidrosis [1 month (4 weeks) after treatment]: Satisfaction will be assessed using a 5-point Likert scale ranging from very dissatisfied to very satisfied following intradermal botulinum toxin type A injections. Higher scores indicate greater satisfaction and improved perceived symptom control
• Incidence of adverse effects following Botulinum toxin type A injections [Within 1 month (4 weeks) after treatment]: Assessment of local and systemic adverse effects following intradermal Botulinum toxin type A injections. Reported complications may include brow ptosis, upper eyelid ptosis, pain at injection site, bruising, headache, and transient weakness. Adverse events will be recorded and classified as present or absent during the 4-week follow-up period

Sex: All, ages: 18 Years to 40 Years

Inclusion Criteria:

* Patients aged between 18 and 40 years.

Clinically and objectively confirmed primary focal frontal hyperhidrosis, defined by sweat production >50 mg/min and a Hyperhidrosis Disease Severity Scale (HDSS) score ≥3 (moderate to severe).

Inadequate response to topical antiperspirant therapy.

No prior treatment with Botulinum toxin type A within the last 6 months.

No use of any other hyperhidrosis treatment within the last 3 months.

Exclusion Criteria:

* Secondary hyperhidrosis due to systemic conditions such as hyperthyroidism, diabetes mellitus, or neurological disorders.

Neuromuscular disorders including myasthenia gravis or Lambert-Eaton syndrome. Active dermatological conditions or anatomical abnormalities in the frontal region (e.g., infections, inflammation, scars).

Known hypersensitivity to Botulinum toxin or any of its components. Pregnancy or breastfeeding. Use of medications that may interfere with Botulinum toxin activity (e.g., aminoglycosides) within one month prior to treatment.

• Campanati A, et al. Treatment of Forehead Hyperhidrosis with Incobotulinum Toxin Type A. Clin Cosmet Investig Dermatol. 2022;15:1-4.
• Boger A, Herath H, Rompel R, Ferbert A. Botulinum toxin for treatment of craniofacial hyperhidrosis. J Neurol. 2000 Nov;247(11):857-61. doi: 10.1007/s004150070073. PMID 11151418
• Lowe NJ, et al. Treatment of hyperhidrosis with botulinum toxin type A. J Clin Aesthet Dermatol. 2023;16(3):20-25.
• Glaser DA, Hebert AA, Pariser DM, Solish N. Interventions for hyperhidrosis in secondary care. Cochrane Database Syst Rev. 2016;CD010036.
• Grabell DA, Hebert AA. Hyperhidrosis: current management. Clin Cosmet Investig Dermatol. 2017;10:829-833.

• Zeinab Y Mohammad, MD, Principal investigator, Latakia University