Rapid Relief of Thalamic Pain Syndrome Induced by Vestibular Caloric Stimulation

Sometimes patients of stroke do not completely recover from their condition. Their stroke condition can lead to the lesioning of the lateral thalamus which coordinates to an unrelenting pain of half of the body.  This condition is called the Chronic Thalamic Pain; and is untreatable by any known medical means, at least for now.

A group of medical doctors and researchers headed by Neurologist Vilayanur S. Ramachandran thought about the relationship between human system discrepancies, as in deviation from the norm (in this case interference of pain), and its representation in the thalamus. Since vestibular signals also lead to the thalamus, the thalamus now is like a road resulting to the convergence of separate roads of pain and vestibular senses. The researchers thought of stimulating the vestibular senses to tap on and alleviate the pain felt by the patient.

Vestibular Caloric Stimulation Model

Method

The researchers asked for the informed consent of two patients suffering from Chronic Thalamic Pain; namely FY- an 87 year old man whose left side of his body is affected, and CC- a 69 year old woman whose right side of the body is affected.

To conduct the experiment, patients' ears are irrigated with either temperate (body temperature) for the control/placebo condition and cold (4°C) water for the actual experimental condition (see picture above). During the process, patients are asked to report any feelings of vertigo, change in perceived body pain on a scale of 0 (no pain at all) to 10 (most pain imaginable), and their eyes were checked for nystagmus.

Results

Both patients have reported decreased pain after being irrigated with cold water. While the expected placebo condition where they tell the patient that pain will be relieved, did not result to any effects; rather the patient still felt the same magnitude of pain. Inrerestingly, patients were checked after 7 weeks and the relief level is the same as the immediate post treatment. 

Discussion

The findings show and support the assumption that vestibular caloric stimulation can regulate thalamic pain in a theraputic fashion. The researchers discredits placebo effects playing a role in the experiment for  number of reasons: that pain relief has lasted for weeks after cold caloric irrigation for both patients; that the placebo conditions did not produce any significant manifestation, that neither patient experienced any pain relief after any epidural injections of local anesthetic designed to treat pain and that the patients knew its function beforehand, and; that the patients reported independent parts involved in pain reduction.

It should be remembered that thalamic pain is resistant to treatment; and so this may be considered as a medical breakthrough but only to be classified as a therapy. Nevertheless, this notorious condition has, for the first time in the history of neurology, became manageable and and moderated via non-invasive means.

Reference:
Ramachandran, Vilayanur S., McGeoch, Paul D., Williams, Lisa and Arcilla, Gerard (2007) 'Rapid Relief of Thalamic Pain Syndrome Induced by Vestibular Caloric Stimulation', Neurocase, 13:3, 185 - 188. Retrieved from http://cbc.ucsd.edu/pdf/rapid%20relief%20caloric.pdf