Alexander Thiel, PhD

Associate Professor, Department of Neurology & Neurosurgery
McGill University at SMBD Jewish General Hospital and Lady Davis Institute for Medical Research
(514) 340 8222 Ext. 5844

Dr. Alexander Thiel is Associate Professor in the Department of Neurology and Neurosurgery at McGill University. As a stroke neurologist, he is Director of the Neuroplasticity Research Program at the Lady Davis Institute for Medical Research (LDI) and Director of the Stroke Unit at the Jewish General Hospital (JGH).

After graduating from the medical school of Bonn University in 1994, he started his research training at the Max-Planck-Institute for Neurological Research in Cologne, followed by a fellowship in brain imaging with Dr. Evans at the Montreal Neurological Institute in 2000. After finishing his residency in neurology and psychiatry at Cologne University, he became a specialist neurologist at the Clinic for Neurology at Cologne University in 2004. In 2006, Dr. Thiel came to McGill. His neuroplasticity laboratory at the LDI and JGH is the first non-invasive brain stimulation laboratory officially certified for clinical use in a stroke unit in Canada. This allows for serial studies in acute stroke patients from the early stages of disease to the early rehabilitation phase – the critical interval during which most neuroplastic processes in the brain occur. Within the wider McGill Stroke Initiative, the Neuroplasticity Research Program (NRP), emphasizes translational research that will bring new evidence-based treatments to patients sooner, and is closely tied to the JGH’s Comprehensive Stroke Centre, of which Dr. Thiel is the Director.

Major Research Activities

The overall goal of the neuroplasticity research program is to develop imaging predictors and new therapeutic strategies for post-stroke recovery. Although initial stroke severity is correlated with outcome, it is a poor predictor for the extent of recovery. Contrary to widely held beliefs, severely affected stroke patients may have the greatest benefit from early and intensive treatment. Identifying such patients soon after a stroke is, thus, of clinical importance for planning treatment. Using functional, morphological, and molecular imaging, Dr. Thiel’s research has indentified three key parameters and pathophysiological mechanisms which determine the outcome and recovery from motor and language deficits following a stroke:

1) Using diffusion tensor imaging (DTI), a new MRI technique, he was the first to reconstruct the entire motor fibre tracts in the brain of patients with subcortical stroke. Such measurements represent the severity of ischemic tract damage and, as such, are highly correlated with clinical deficit and outcome.

2) Imaging activated microglia, the main cellular component of post-stroke neuroinflammation. With PK11195-PET, he was able to predict secondary (Wallerian) degeneration of fibre tracts. Patients exhibiting high levels of persisting microglia activation around the infarct and along the affected tract, exhibited accelerated degeneration and worse clinical outcomes.

3) Using transcranial magnetic stimulation (TMS), an electrophysiological method to modulate electrical brain activity, he performed the first prospective, controlled pilot studies on non-invasive brain stimulation for improving recovery from aphasia after stroke. This new technique may be used as adjuvant therapy to conventional speech and language therapy in patients with post-stroke aphasia to normalize brain activation patterns and improve recovery. TMS promises to become the first effective supplementary therapy for treatment of post-stroke deficits and is currently being evaluated also for motor deficits in larger patient samples.