The “Suicide Disease”: An Interview with Dr. Mojgan Hodaie

The “Suicide Disease”: An Interview with Dr. Mojgan Hodaie

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Dr. Mojgan Hodaie, MSc, MD
Scientist, Krembil Research Institute
Affiliated Faculty, Techna Institute for the Advancement of Technology for Health (Techna)
Associate Professor of Surgery, Faculty of Medicine, University of Toronto

By: Akshayan Vimalanathan

Trigeminal neuralgia (TN) was historically dubbed the ‘suicide disease’ because many individuals with the condition developed suicidal tendencies, preferring death over the pain. Arguably considered the most painful condition known to humankind, TN is a rare chronic pain disorder characterized by sporadic episodes of severe facial pain originating from the trigeminal nerve (CN-V). These episodes occur suddenly and spontaneously, lasting anywhere from a few seconds to a few minutes. According to the National Institute of Health, the disorder affects approximately 12 out of every 100,000 people per year.1 As a staff neurosurgeon at Toronto Western Hospital with clinical expertise in neuropathic pain, Dr. Mojgan Hodaie witnesses first-hand the debilitating nature of TN. Her dual role as a clinician-scientist allows her to address the welfare of people suffering with TN from both fronts.

Dr. Hodaie is a professor in the Department of Surgery at the University of Toronto (UofT) and a scientist at the Krembil Research Institute. She completed her neurosurgery residency and fellowship in stereotactic and functional neurosurgery at the UofT. With a special focus in neuropathic pain, she developed a particular interest in TN.

“One [area] that was very attractive to me, within the field of functional neurosurgery, was pain. Pain is a peculiar thing, as it’s a shared human experience that is generally thought of as subjective, therefore difficult to understand and make sense of. We can think of pain as an entity onto itself that involves the whole central nervous system (CNS) and is very complex, [but] are there also ways where we can think of pain as essentially a surgical problem? And that was, I think, one of the most fascinating things for me,” says Dr. Hodaie.

Classical TN is the result of a blood vessel pressing against the trigeminal nerve as it exits the brain stem, causing neurovascular compression of the nerve. The pulsating blood vessel rubs on the nerve and can slowly wear away the myelin sheath protecting it, creating small pockets of focal demyelination. This produces subsequent crosstalk between sensory and pain fibers, leading the brain to misinterpret mild facial sensations as stabbing pain. TN has drawn comparisons to the feeling of being electrocuted. “[Patients] describe it as a 10,000-volt electric surge,” reveals Dr. Hodaie. Interestingly, the attacks are triggered by very innocuous activities such as touching the face, eating, talking, or even being exposed to the wind.1 To combat these triggers, patients will often avoid these daily activities entirely, becoming very emaciated and socially withdrawn.

Fortunately for people suffering with TN, surgical options exist which offer long-term pain relief. For those who are otherwise physically healthy, microvascular decompression is the preferred surgical treatment. The procedure involves entering the brain through a small incision behind the ear, locating the trigeminal nerve, and lifting the offending vessel off the nerve so that a piece of shredded Teflon can be placed in between.

As Dr. Hodaie explains it, “We need to put something that cushions the nerve and dampens the pressure of the blood beating within the vessel. We need that something to be inert, so it doesn’t cause an inflammatory reaction. The best candidate that we have is just a piece of shredded Teflon, [which is] like a white sponge.”

However, for those who are physically ill, have additional risks for surgery, or are older in age, microvascular decompression can be potentially dangerous. In these cases, Gamma Knife radiosurgery is recommended. By directing highly focused beams of radiation at the site where the trigeminal nerve exits the brainstem, the procedure creates a lesion on the nerve that disrupts sensory signal transmission to the brain.1 In most cases, surgical treatments provide complete relief from pain. However, interestingly, the pain reoccurs for select individuals. At present, it is not understood why such individual differences exist in response to treatment.

Dr. Hodaie and her team are exploring ways to use advanced brain imaging to help improve neurosurgical outcomes for patients, and to better understand TN. She has already made notable contributions to the field of functional neurosurgery, pinpointing key neuroanatomical signatures in TN and introducing imaging adjuncts that inform surgical diagnosis and treatment.

“Uniformly, the way TN has been studied is by way of clinical studies, purely relying on the subjective reports of patients. I think our work has been the first instance where a measure of objectivity was introduced in studying this pain syndrome,” says Dr. Hodaie.

Using diffusion tensor imaging/tractography, Dr. Hodaie’s lab has identified imaging correlates specific to TN, which serve as adjuncts to clinical data. “What we’re able to find is essentially a signature of pain that is left on the trigeminal nerve. If you look at the nerve microstructure, there are specific areas where we see distinct structural changes. It indicates, potentially, a nerve that is very much compressed. Without advanced MR imaging, tiny details like this get missed. And so, [having] this measure of objectivity and having real imaging modalities [to] study a condition that has been forever subjective… that really, I think, is my greatest contribution.”

Another aspect of Dr. Hodaie’s work focuses on understanding how the presence of pain impacts the CNS in its entirety. How is neuropathic pain, particularly TN, represented in the brain? Are there gray and white matter CNS changes associated with TN? These are fundamental questions that Dr. Hodaie attempts to address using structural imaging techniques like cortical thickness analysis and voxel-based morphometry. The thickness of the cerebral cortex and the pattern of cortical folds provide valuable information for understanding disease progression, for identifying affected brain regions, and possibly for assessing treatment.2 By looking into CNS-related features of TN that until now were entirely unknown, she hopes to delineate the role they play in the ongoing nature of this pain.

Speaking on her findings, Dr. Hodaie points out, “We found, in fact, that there were changes not only restricted to the trigeminal area, but very much within the brain–in the cortex, in the subcortical gray, and in the white matter. And these were primarily in areas that are important for the modulation and perception of pain. It is quite possible that two patients that are identical in terms of neurovascular compression can [experience] different kinds of pain because of the CNS top-down modulation effect of that pain.”

When asked what inspires her research, Dr. Hodaie recalls a defining moment in her career: “As a resident, I had the unique blessing of meeting one of the fathers of functional neurosurgery, Ron Tasker. I distinctly remember we were having a session with [him] and one of the questions that I asked was, ‘Will there be an opportunity one day in which we can think of pain in an objective manner and not always as a subjective problem?’ He shared some very clear and tangible ideas about pain that I found extremely interesting. That session and that question has stayed with me and has really formulated a lot of my research.”

While there are still many unanswered questions regarding TN, Dr. Hodaie is optimistic about the current progress of the field, “We hope that in the near future, the imaging capabilities we have developed will help us predict who will respond well to treatment and allow us to establish a personalized medical approach.”

References

  1. Trigeminal Neuralgia Fact Sheet [Internet]. National Institute of Neurological Disorders and Stroke. U.S. Department of Health and Human Services; 2013 [cited 2018 May 3]. Available from: https:// www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Fact-Sheets/Trigeminal-Neuralgia-Fact-Sheet
  2. Hutton C, Vita ED, Ashburner J, Deichmann R, Turner R. Voxel-based cortical thickness measurements in MRI. NeuroImage. 2008 May;40(4):1701–10.