Central pain in a hemispherectomized patient

Area of Science:

• Neuroscience
• Pain Research
• Clinical Neurology

Background:

• Hemispherectomy, a surgical removal of one brain hemisphere, can lead to complex neurological deficits.
• Central pain syndromes can manifest as abnormal sensations, including allodynia (pain from non-painful stimuli).
• Temperature sensitivity changes are sometimes reported in patients with neurological damage.

Purpose of the Study:

• To investigate the characteristics of touch-evoked pain (allodynia) in a patient who underwent hemispherectomy.
• To explore the neurobiological underpinnings of central pain in this patient using functional magnetic resonance imaging (fMRI).
• To examine the influence of ambient temperature on pain perception.

Main Methods:

• Psychophysical testing to assess sensory perception, including temperature discrimination and brush-evoked allodynia.
• Functional magnetic resonance imaging (fMRI) to observe brain activity during symptomatic allodynia.
• Clinical examination of a patient with a history of hemispherectomy.

Main Results:

• The patient exhibited allodynia to brush stroking, which was exacerbated by cold ambient temperatures.
• Impaired temperature perception (confusion of cool and warm) was noted on the paretic side.
• fMRI revealed activation in brain regions typically associated with normal pain processing, including the anterior cingulate cortex, secondary somatosensory cortex, and prefrontal cortices, during brush-evoked allodynia.

Conclusions:

• Central pain in this hemispherectomized patient appears to be processed by neural structures involved in normal pain pathways.
• Potential pathophysiological mechanisms may involve neural plasticity and thalamic disinhibition.
• These findings highlight the complex interplay between brain structure, sensory processing, and pain perception following hemispherectomy.