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.

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.