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Botox A for use in Sialorrhoea

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Objective

To reduce the severity and frequency of drooling (dribbling/sialorrhoea)

Background

Hypersalivation (sialorrhoea, drooling) is an important social, clinical and emotional issue for people with severe neurological disease such as cerebral palsy. Salivation is controlled via the autonomic nervous system. The salivary glands function is under a complex parasympathetic and sympathetic neural control. Nerve endings within the parasympathetic postganglionic system secrete acetylcholine, and blocking these receptor sites inhibits nervous stimulation to the salivary glands. Botulinum toxin type A (BTX), diminishes salivary flow rate by blocking this release of acetylcholine.1

Clostridium Botulinum, an anaerobic bacterium, yields seven antigenically distinct toxins: A,B,D,E,F and G. These are potent neuroparalytic agents, which inhibit the release of acetylcholine at the neuromuscular junction. The effects of BTX are however temporary. The toxin penetrates the endosomal membrane where the secretion of acetylcholine is blocked. The different toxins are structurally similar but have slightly varying effects. To date only preparations of Botox-A have been available for clinical use. There has been some evidence that BTX has a longer lasting effect at the neuroglandular junction compared to the neuromuscular junction3 (12 months as opposed to 3 months). Re-innervation at the neuromuscular junction is due to re-sprouting of nerve branches. It is noted that authors report a variation in the length of the effect from 2 weeks to 6 months.

Present treatments (Table -1) for drooling have had limited success. Anticholinergic drugs taken orally or transdermally can have significant side effects. Common adverse effects include constipation and irritability or urinary retention. Surgery involving salivary gland removal or duct redirection is the most popular and accepted management but is also associated with complications. Apart from the usual possible anaesthetic and peri-operative complications, increased dental caries, salivary gland calculi and excessive oral dryness can occur. Most patients require combination of treatment options.

Injection of salivary glands with BTX has emerged as a new treatment since year 2000. This results in a reduction in saliva production and improvement in drooling.

BTX is an effective treatment for a variety disorders with different aetiologies and has been said to have very few side effects. There are several studies in the literature which have reported the use in children2.3.4.8.10 but the numbers used in these studies are relatively small. The efficacy of this treatment option varies from patient to patient and therefore should be used with caution in children.

Treatment Options for Sialorrhoea

  • Medications - anticholinergics such as atropine and glycopyrolate
  • Behavioural modifications and physical therapy
  • Oromotor rehabilitation / therapy by Speech Therapist
  • Orthodontic treatment
  • Improvement of nasal and oral airway patency - Otolaryngology (ENT)
  • Catellio moreles prosthesis
  • Surgery to the salivary glands
  • Botox injection to submandibular / parotid glands
  • No treatment

Patient Selection

All patients who are considering Botox injection should undergo a multidisciplinary assessment at the Saliva Clinic prior to being placed on the waiting list. Children under the age of 5 and adults over 18 should not be considered at the Starship Children's Hospital. They should be fully informed of all treatment options available and suitability of each of these options prior to selecting Botox injection. The clinic pamphlet should be sent to the family to read prior to their clinic appointment so that they are then able to clarify details of the treatment. Consent for the procedure will be obtained at the clinic appointment.

Caution: Patients with pre-existing swallowing difficulties are not automatically excluded but should be considered only after consideration of all other options.

Written consent for the procedure will have been gained on the day of the clinic appointment. The consent should specify which gland/s are being injected and proposed dose and volume should be discussed and documented. The potential complication of paralysis of adjacent musculature and swallowing difficulties should specifically mentioned. The surgeon will visit the patient and family on the day of the procedure and ensure that the family understand the procedure to be carried out. Consent for anaesthesia will be gained on the day of the procedure. 

Dose / Volume / Dilution

Dose

These doses relate to the Allergan Botox preparation.

These recommendations for dose, volume and dilution are conservative. They are a rough guidelines based on the limited case series described in the literature. The dose should be titrated to the individual patient depending on the ultrasound appearance of the salivary glands.

But as a general rule:

  • Maximum dose per submandibular gland should not exceed 15 units.
  • Maximum dose for both submandibular glands is 30 units.
  • Maximum dose per parotid gland should not exceed 10units.
  • Maximum dose for both parotid glands is 20 units.
  • Total maximum dose per patient should not exceed 50 units.

Botox given for the first time should only be given to submandibular glands. Second and subsequent doses can be given to both glands if there is no response to the first injection. Dose per submandibular gland should be dictated by the size of the gland however in children under the age of 10, a smaller dose should be considered. Example 8-10 units per submandibular gland in children under 20 kg weight, rather than the 15 units/per gland. A similar rule applies to when considering injection in the parotid glands. Injections can be repeated up to a maximum of 2 injections 4 months apart.

Volume

The volume of injection will depend on the dose and dilution used. Adhering to the dosing schedule shown above the total injected volume should be less the 0.5 ml (total to all glands).

Dilution

Botulinum toxin-A (Allergan) should be diluted with normal saline 0.9%. 100U vial should be diluted with 1ml of normal saline 0.9%. No other dilution methods should be used. Standard Thermo syringe or 1ml syringe should be used.

Administration / Monitoring / Precautions

Administration

Botox should be administered under ultrasound guidance at all times. If ultrasound is not available then the procedure should be postponed. An experienced sonographer is essential. A small 1 ml Thermo syringe and 3cm length 25 gauge / or 27 gauge needle should be used for accurate placement. It is useful to place injections within the capsule and multiple intraglandular sites x3, three sites maximum per gland. Placement of the injection well within the glandular tissue reduces the risk of extravasation outside the capsule. Up to 2 sites may be injected within a gland.

At the end of the procedure record the dose given to each gland and the discarded units of Botox. Surgeon or a member of the team should talk to the parents after the procedure and discuss dose and volume if necessary.

Monitoring

Post injection the children should be monitored in the Daystay Unit for 4-6 hours prior to discharge. The post operative instruction sheet should be given and explained to parent and caregiver prior to discharge. A phone call check on the patient in 3-4 days to check the efficacy of the Botox by a member of the team is also useful. All patients should be followed up in clinic at 6 weeks to check progress. Patient's database must be maintained to document dose and outcome using the standard drooling questionnaire.

Safety Precautions

Ensure that the medication is drawn up by the practitioner who is to administer the Botox - this is to avoid any misunderstanding on diluent volumes.

Do not shake the vial vigorously as the medication can become inert.

References

Please note that the doses below could refer to any number of a variety of preparations available and the reader is advised to check the references for the preparation used.

Reftable1

Reftable2

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Document Control

  • Date last published: 01 May 2005
  • Document type: Clinical Guideline
  • Services responsible: Paediatric ENT
  • Author(s): Murali Mahadevan
  • Editor: Greg Williams
  • Review frequency: 2 years

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