Botulinum Toxin A Might Be an Alternative or Adjunct Therapy for the Treatment of Trigeminal and Postherpetic Neuralgia

Botulinum Toxin A Treatment in HIV Infected Patients-A Long-Term Observational Study

OBJECTIVE

It is unknown whether interactions between HIV infection and the safety of botulinum toxin A (BTX) exist.

METHODS

We studied eight patients with HIV infection who were treated with BTX every three months for up to nine years. All patients were on antiretroviral treatment. The efficacy and safety of BTX were evaluated.

RESULTS

Indications for BTX treatment (including off-label use), dosage of BTX, and frequency of application did not differ as compared to non-HIV infected patients. BTX treatment was effective in all HIV infected patients during a long-term observation period without loss of efficacy and without clinically relevant side effects. Only one of the eight patients showed mild side effects due to BTX, and no clinical signs of antibody development were noted. We also observed no signs of interaction with antiretroviral treatment. CD4+ cell count and viral load remained stable during the observation period.

CONCLUSIONS

We conclude that BTX treatment is safe and effective in the treatment of HIV infected patients who suffer also from a condition which can be treated by BTX. It is a therapeutic option in addition to oral medication for HIV infected patients.

Trigeminal neuralgia: An overview from pathophysiology to pharmacological treatments

The trigeminal nerve (V) is the fifth and largest of all cranial nerves, and it is responsible for detecting sensory stimuli that arise from the craniofacial area. The nerve is divided into three branches: ophthalmic (V1), maxillary (V2), and mandibular (V3); their cell bodies are located in the trigeminal ganglia and they make connections with second-order neurons in the trigeminal brainstem sensory nuclear complex. Ascending projections via the trigeminothalamic tract transmit information to the thalamus and other brain regions responsible for interpreting sensory information. One of the most common forms of craniofacial pain is trigeminal neuralgia. Trigeminal neuralgia is characterized by sudden, brief, and excruciating facial pain attacks in one or more of the V branches, leading to a severe reduction in the quality of life of affected patients. Trigeminal neuralgia etiology can be classified into idiopathic, classic, and secondary. Classic trigeminal neuralgia is associated with neurovascular compression in the trigeminal root entry zone, which can lead to demyelination and a dysregulation of voltage-gated sodium channel expression in the membrane. These alterations may be responsible for pain attacks in trigeminal neuralgia patients. The antiepileptic drugs carbamazepine and oxcarbazepine are the first-line pharmacological treatment for trigeminal neuralgia. Their mechanism of action is a modulation of voltage-gated sodium channels, leading to a decrease in neuronal activity. Although carbamazepine and oxcarbazepine are the first-line treatment, other drugs may be useful for pain control in trigeminal neuralgia. Among them, the anticonvulsants gabapentin, pregabalin, lamotrigine and phenytoin, baclofen, and botulinum toxin type A can be coadministered with carbamazepine or oxcarbazepine for a synergistic approach. New pharmacological alternatives are being explored such as the active metabolite of oxcarbazepine, eslicarbazepine, and the new Nav1.7 blocker vixotrigine. The pharmacological profiles of these drugs are addressed in this review.

Botulinum toxin type A in chronic neuropathic pain in refractory leprosy

OBJECTIVE

Neuropathic pain is a chronic syndrome that is difficult to treat and often affects patients with leprosy. Recommended treatment includes the the use of analgesic drugs, codeine, tricyclic antidepressants, neuroleptics, anticonvulsants and thalidomide, but without consensus on uniform dose and fully satisfactory results. To analyze botulinum toxin type A (BoNT-A) effectiveness in treatment of chronic neuropathic pain in refractory leprous patients, as well as evaluate and compare the quality of life of patients before and after using the medication.

METHODS

We used a specific protocol including clinical, demographic, DN4 protocol, analogue scale (VAS), sensory evaluation and evaluation of the WHOQOL-BREF. Therapeutic intervention was performed with BOTOX® BTX-A 100U administered subcutaneously. Fifteen patients were evaluated on days 0, 10 and 60.

RESULTS

Patients on VAS showed pain between 5 and 10, in one case there was complete pain relief in 60 days, while others showed improvement in the first week with the return of symptoms with less intensity after this period. WHOQOL-BREF's domains Quality of Life and Physical to have a significant increase in QOL.

CONCLUSION

BoNT-A proved to be a good therapeutic option in relieving pain with improved quality of life for these patients.

Antidepressant-Like Action of Single Facial Injection of Botulinum Neurotoxin A is Associated with Augmented 5-HT Levels and BDNF/ERK/CREB Pathways in Mouse Brain

The present study was designed to examine the therapeutic effects of Botulinum neurotoxin A (BoNT/A) on depression-like behaviors in mice and to explore the potential mechanisms. These results revealed that a single facial injection of BoNT/A induced a rapid and prolonged improvement of depression-like behaviors in naïve and space-restriction-stressed (SRS) mice, reflected by a decreased duration of immobility in behavioral despair tests. BoNT/A significantly increased the 5-hydroxytryptamine (5-HT) levels in several brain regions, including the hippocampus and hypothalamus, in SRS mice. BoNT/A increased the expression of the N-methyl-D-aspartate receptor subunits NR1 and NR2B in the hippocampus, which were significantly decreased in SRS mice. Furthermore, BoNT/A significantly increased the expression of brain-derived neurotrophic factor (BDNF) in the hippocampus, hypothalamus, prefrontal cortex, and amygdala, which were decreased in SRS mice. Finally, BoNT/A transiently increased the levels of phosphorylated extracellular signal-regulated kinase (p-ERK) and cAMP-response element binding protein (p-CREB), which were suppressed in the hippocampus of SRS mice. Collectively, these results demonstrated that BoNT/A treatment has anti-depressant-like activity in mice, and this is associated with increased 5-HT levels and the activation of BDNF/ERK/CREB pathways in the hippocampus, supporting further investigation of BoNT/A therapy in depression.