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Numerous studies demonstrate that botulinum toxin A is an effective treatment for muscular spasticity, tremors, and other muscular problems that are associated with specific diseases.

Numerous studies demonstrate that botulinum toxin A is an effective treatment for muscular spasticity, tremors, and other muscular problems that are associated with specific diseases.

Cynthia R. Biron, RDH

Botulism has a negative connotation, since it is well-known as food poisoning. The botulinus toxins A through G of the bacteria, Clostridium botulinum, are responsible for the manifestations of the infection. The anaerobic bacteria is originally found in the soil and intestinal tracts of domestic animals. When food products such as meats and nonacidic vegetables are contaminated with the bacteria and then ingested by humans, the toxin binds to the nerve end-plate, preventing acetylcholine release and causing presynaptic neuromuscular blockade. In food poisoning, the toxin selectively affects cardiac and respiratory systems through the medullary center.

However, when botulinum toxin A (BTX) is injected locally at specific neuromuscular sites in the body, selected muscles are paralyzed and miraculous effects are almost immediate. Botulinum toxin A has become most well-known for removing wrinkles and frown lines by injecting the corrugator, porcerus, and portions of the orbicularis oculi muscles.

Numerous studies demonstrate that botulinum toxin A is an effective treatment for muscular spasticity, tremors, and other muscular problems that are associated with diseases such as cerebral palsy (CP), Parkinson`s disease (PD), muscular sclerosis (MS), post-stroke spasms, and other conditions.

Of special interest to dental professionals is the BTX treatment of conditions such as oromandibular dystonia, hemifacial spasms, drooling in PD, and temporomandibular disorders.

A long-term study of Botox treatment of 162 patients was conducted at the Parkinson`s Disease Center and Movement Disorders Clinic in the department of Neurology at Baylor College of Medicine in Houston, Texas. This type of dystonia is not usually relieved by drugs, and, to date, there are no corrective surgical procedures available.

BTX was injected into the masseters and/or submentalis complex at 1,213 treatment appointments. In a range of 0-4, with 4 being complete elimination of dystonia, the mean global effect of BTX injections was 3.1+/-1.0 after approximately four years. Of the 162 patients treated, 51 patients experienced adverse effects at one or more treatments; 135 of the 1,213 treatment appointments were complicated by transient adverse effects such as dysphasia (speech impairment) or dysarthria (impairment to tongue or muscles of speech). This study showed that BTX is a relatively safe, long-term treatment for oromandibular dystonia.

At the same department at Baylor, a study was conducted that compared BTX with microvascular decompression as treatments for hemifacial spasms; 105 of the 110 patients treated with BTX injections experienced marked to moderate improvement in their symptoms. Of the 25 patients with microvascular decompression, seven experienced permanent complications, and five experienced recurrence of hemifacial spasms. Nine patients with drooling from PD were given intraparotid injections of BTX, and all experienced a marked reduction in secretion, while two-thirds experienced an improvement in drooling. Fifteen patients with temporomandibular joint disorders received BTX injections in masseter and temporalis muscles. For eight consecutive weeks, assessments revealed significant improvement in pain, tenderness, and function without any side effects.

Other conditions treated with BTX

- Cerebral palsy - CP is a disorder that has a diverse group of nonprogressive syndromes that affect the brain and cause motor dysfunction. In addition to seizure disorders, mental retardation, and developmental disability, patients develop spasticity in the first year of life and are prone to contractures that can worsen if not properly treated. The muscle contractures can affect any or all of the limbs, interfering with normal functions.

CP patients treated with BTX injections have experienced reduced energy cost of movement and improved endurance of spastic muscles. Higher dosages of BTX produce greater reduction in muscle contractures.

- Parkinson`s disease - PD is a degenerative disease of the basal ganglia involving dopamine secretion. The main characteristics of the disease include tremor, rigidity, and poverty of movement. L (L-dopa) is the drug used to treat PD in later stages. The drug therapy is postponed due to adverse effects.

BTX has been effective in treating the manifestations of PD. More research needs to be conducted to determine the extent of the effectiveness of BTX in PD patients with regard to long-term effects.

- Multiple sclerosis - MS is a degenerative disorder diffusely involving CNS myelin. Several syndromes are common to the various types of MS relative to the areas of the CNS where the myelin is affected. The corticospinal syndrome is the most common, involving the corticospinal tracts and dorsal column. Lower limbs are often more involved than upper limbs, with spastic paraparesis being the most common neurological finding in MS.

BTX injections have been shown to improve flexion and extension of the lower leg and foot in progressive multiple sclerosis patients. Larger studies need to be conducted to determine the extent of effectiveness for various types of MS.

- Post-stroke - Not only does a stroke cause paralysis, it causes spasticity and muscle contracture. A study conducted with 20 patients who presented with post-stroke ankle plantar flexor and foot invertor spasticity involved BTX injection into calf muscles or tibial nerve blockade with 3 ml of 5 percent phenol. The results showed improvement in dorsiflexion of BTX-injected subjects at weeks two and four, with no changes at weeks eight and 12. An improvement in clonus duration in both groups was significant at all weeks (P > 0.05).

Combinations of treatments

- Stroke-related spasticity - A combination of (BTX) and electrical stimulation was more effective than BTX alone in the treatment of chronic upper limb spasticity in post-stroke patients. A randomized, double blind study of four groups of six patients in each taking 1) BTX and electrical stimulation, 2) BTX alone, 3) placebo alone, and 4) electrical stimulation alone. The greatest improvements were shown in the first group (P = 0.004).

Spinal cord injury patients with severe spasms are often treated with intrathecal baclofen. An incomplete T12 paraplegic patient had severe painful spasms in the lower limbs, but refused to have intrathecal baclofen therapy. In a two-year follow-up study, this patient was treated with BTX and demonstrated significant improvement. Because BTX treatments are expensive and reversible, it has been suggested that it be used in combination with the more affordable baclofen treatment.

- Tension headaches - Patients with tension headaches (n=9), who did not respond to traditional treatments of physical therapy and/or medications were treated with BTX injections. The injections were in the frontal, temporal, occipital, and sternocleidomastoid muscles. Eight of the nine patients completed the eight-week study. All the patients kept a headache diary. The diaries were used to calculate the area under the headache curve (AUC) for comparison of the four weeks before the BTX injections and the four weeks after the injections. Those completing the study showed a significant reduction in headaches according to the headache curve (AUC). The mean AUC in the 4 weeks prior to injections was 404, and in the 4 weeks after BTX injections was reduced to 196 (p = 0.039).

- Achalasia - Achalasia is dysfunction of esophageal sphincter muscles that involve the middle and lower portion of the esophagus and/or the lower esophageal sphincter functioning. The clinical manifestations include distention and spasm of esophageal muscles during eating and drinking, which causes difficulty swallowing and pain at the site of the distention. The usual treatment includes anticholinergic drugs or surgery. Thirty patients received BTX injections for achalasia, and 23 (77 percent) experienced symptomatic improvement for three months after the injections. Of the 23, seven had a longer period of relief (mean follow-up, 21 months). The remaining 16 eventually relapsed (mean follow-up 11 months). Those that responded to the initial BTX injections responded well with subsequent BTX treatment; those that did not respond well with initial injections did not respond well with subsequent injections.

- Frey`s syndrome - Frey`s syndrome (gustatory sweating) is a condition brought on by damage to the parasympathetic innervation of cutaneous sympathetic receptors during surgery on the parotid gland. Various surgical procedures have been attempted to correct the problem with no real success. Seven patients were treated with BTX injections. All of them reported that the gustatory sweating had stopped completely in the area injected. Six patients required injections up to four more times before being symptom-free for 12 months. There were no adverse effects from the treatments, and BTX injections have been strongly recommended for this syndrome.

Studies have been conducted on other conditions with BTX injections as a treatment. Some of the studies include: childhood myoclonus, tics in Tourette syndrome, pathologic lacrimation, whiplash-associated neck pain, writer?s cramp, sixth cranial nerve palsy, hyperadduction of false vocal folds, and tracheosophageal speech after laryngectomy.

The greatest drawback with BTX injections is cost. The BTX itself costs approximately $400. The physician?s fee for administering it varies from $50 to $200. If medical insurance companies cover the cost of the treatment, it will become more common as a treatment for the many conditions mentioned in this article, as well as other conditions not yet studied for treatment with BTX.

References available upon request.

Cynthia R. Biron, RDH, is chair of the dental hygiene program at Tallahassee Community College. She is also a certified emergency medical technician.

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