Dissertation
Mapping central post-stroke pain and somatic complaints in patients with brain lesions
University of Iowa
Doctor of Philosophy (PhD), University of Iowa
Spring 2025
DOI: 10.25820/etd.008000
Abstract
Our health and well-being are intimately dependent on how our brain represents and interprets signals from the body. However, how the brain encodes bodily information and attributes positive or negative qualities to those perceptions remains incompletely understood, particularly from a neuroanatomical perspective. It is well known that lesions in certain brain regions are associated with a more negative perception of the body—manifesting as intractable pain without a nociceptive trigger—referred to as central post-lesion pain or central pain syndrome (CPSP). Other lesions may have more subtle effects on bodily interpretation, such as increasing or decreasing the likelihood of somatic complaints.In this study, we evaluated the relationship between lesion location and subjects’ evaluations of body states, ranging from pain to somatic complaints. The overall objective was to determine whether lesion location is associated with differences in the experience of pain and somatic complaints in individuals with acquired brain lesions. Additionally, we explored the relationship between somatic complaints and outcomes such as cognition and mood—an ongoing area of research. Specifically, we examined whether somatic complaints are associated with negative cognitive outcomes and mood disturbances.
To investigate the neuroanatomical substrates of CPSP, we pre-registered our hypothesis regarding likely lesion locations. This a priori region of interest (ROI) included the spinothalamic white matter, a posterior thalamic site previously implicated in CPSP, the insula, and the white matter extending from the thalamus to the insula—a network we termed the “pain pathway.” We tested this ROI using three approaches: Calculating lesion overlap between CPSP and comparison lesions, conducting multivariate lesion-symptom mapping to localize CPSP-associated lesions, and using lesion network mapping to determine broader functional and structural connectivity related to CPSP.
In the lesion intersection analysis, we found that CPSP lesions intersected with the a priori ROI to a greater extent than did comparison lesions. Multivariate lesion-symptom mapping localized CPSP lesions to a ventrocaudal thalamic area and adjacent white matter, largely within our hypothesized region. Lesion network mapping revealed a broader CPSP-associated network, including visual and motor areas. Notably, the implicated motor regions overlapped with the recently described somato-cognitive action network (SCAN).
Next, we investigated whether lesion location was associated with somatic complaints. We used three measures of somatic complaints: the Minnesota Multiphasic Personality Inventory (MMPI), the Beck Depression Inventory (BDI), and the Beck Anxiety Inventory (BAI). We hypothesized that lesions to the left ventromedial prefrontal cortex (vmPFC) would be associated with fewer somatic complaints, whereas lesions to the right vmPFC and the pain pathway would be associated with more somatic complaints. However, due to data limitations, we were unable to consistently localize somatic complaints to any specific brain region.
Lastly, we explored whether somatic complaints were associated with cognitive and affective outcomes. We hypothesized that higher levels of somatic complaints would correlate with lower cognitive scores, along with increased depression and anxiety. To test this, we conducted correlation analyses between somatic complaint scores (measured by the MMPI-2-RF) and cognitive outcomes (measured by the Wechsler Adult Intelligence Scale, WAIS). We also examined correlations between the MMPI-2-RF and both the BDI and BAI to assess mood outcomes. We found strong correlations between somatic complaints and lower IQ scores, higher depression scores, and higher anxiety scores.
Taken together, this work provides new insights into how lesion location relates to CPSP, with important implications for understanding, identifying, and treating this condition. Although we were unable to localize lesions associated with somatic complaints, our findings highlight how such complaints may be linked to poorer cognitive outcomes and increased depression and anxiety.
Details
- Title: Subtitle
- Mapping central post-stroke pain and somatic complaints in patients with brain lesions
- Creators
- Hassan Abdalaziz Karoam
- Contributors
- Aaron Boes (Advisor)Daniel Tranel (Committee Member)Emine Bayman (Committee Member)Nicholas Trapp (Committee Member)Kai Hwang (Committee Member)
- Resource Type
- Dissertation
- Degree Awarded
- Doctor of Philosophy (PhD), University of Iowa
- Degree in
- Neuroscience
- Date degree season
- Spring 2025
- DOI
- 10.25820/etd.008000
- Publisher
- University of Iowa
- Number of pages
- xvi, 105 pages
- Copyright
- Copyright 2023 Hassan Abdalaziz Karoam
- Language
- English
- Date submitted
- 04/21/2025
- Description illustrations
- color illustrations
- Description bibliographic
- Includes bibliographical references (page 84-94).
- Public Abstract (ETD)
Stroke and other central lesions can impact an individual's daily life in various ways. These include functional deficits, language deficits, cognitive disturbances, amongst many other problems. A key question, and ongoing area of research, is how lesion location is associated with these negative clinical outcomes. For the current work, we were interested in understanding how lesion location is associated with two separate but related outcomes: central post-stroke pain (CPSP) and somatic complaints. CPSP, as the name suggests, is a neuropathic post-stroke pain that can have devastating effects on a person’s life. Somatic complaints are bodily disturbances, such as pain, that arise when no trigger is present. The underlying brain locations associated with both CPSP, and somatic complaints have been studied but not well characterized. Another open area of research is whether somatic complaints are associated with worse cognitive and mood outcomes, an aspect of somatic complaints we wanted to dive further into.
We found consistent patterns in CPSP lesion locations including the thalamus and adjacent white matter. The network that was associated with these lesions consisted of the thalamus, insula, motor cortex, and visual areas. Somatic complaints, however, did not localize to a consistent brain region. Although somatic complaints did not localize to a brain region, we discovered that somatic complaints are indeed associated with worse cognitive and mood outcomes. These findings have implications for the identification and treatment of both CPSP and somatic complaints.
- Academic Unit
- Interdisciplinary Graduate Program in Neuroscience
- Record Identifier
- 9984830825802771
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