Carol V. Anderson

Lesion volume, injury severity, and thalamic integrity following head injury.

Magnetic resonance (MR) scans of 63 traumatic brain injury (TBI) patients were analyzed to examine the relationship between injury severity, lesion volume (nonthalamic cortical/subcortical lesions), ventricle-to-brain ratio (VBR), and thalamic volume. For comparison, 33 normal control subjects were used. Patients with visible nonthalamic structural lesions showed significantly smaller thalamic volumes than patients without visible lesions or control subjects. Results also indicated that patients with visible lesions had significantly more severe injuries than patients without lesions. Patients with moderate-severe injuries had significantly smaller thalamic volumes and greater VBRs than patients with mild-moderate injuries. Although several variables related to thalamic volume, the presence of nonthalamic lesions was sufficient to result in smaller thalamic volume. Decreased thalamic volume following head injury suggests that subcortical brain structures may be susceptible to transneuronal degeneration following cortical lesions, and that this can be detected by in vivo MR-based volumetric analysis.

Severe anoxia with and without concomitant brain atrophy and neuropsychological impairments.

Significant anoxia may cause a variety of neuropathologic changes as well as cognitive deficits. We have recently seen 3 patients who have suffered severe anoxic episodes all with initial Glasgow Coma Scores (GCS) of 3 with sustained coma for 10-14 d. All 3 patients had extended hospitalizations and rehabilitation therapy. A neuropsychological test battery was administered and volumetric analyses of MRI scans were carried out in each case at least 6 mo postinjury. Two of the patients display distinct residual cognitive and neuropathologic changes while 1 patient made a remarkable recovery without evidence of significant morphological abnormality. These three cases demonstrate, that even with similar admission GCS, the outcome is variable and the degree of neuropsychological impairment appears to match the degree of morphologic abnormalities demonstrated by quantitative MR image analysis. An important finding of this study is that even though subjects with an anoxic insult exhibit severe cognitive and memory impairments along with concomitant morphologic changes, their attention/concentration abilities appear to be preserved. MR morphometry provides an excellent means by which neural structural changes can be quantified and compared to neuropsychological and behavioral outcomes.

The role of caudate nucleus and corpus callosum atrophy in trauma-induced anterior horn dilation

Day-of-injury computerized tomography (CT) scans were compared to post-injury (at least 6 weeks) magnetic resonance (MR) imaging of 30 traumatic brain-injured (TBI) patients. Scans were matched as closely as possible at the head of the caudate nucleus (CN), a grey matter structure, and the anterior horns (AH) of the lateral ventricle. The CN and AH surface areas and width of the corpus callosum (CC), a white-matter structure, were measured. Results demonstrated a non-significant change in CN surface area, while AH showed a significant increase. CC showed a significant decrease in width. Lack of significant change in the CN, combined with a significant decrease in CC width, suggests that AH dilation is probably due to surrounding white as opposed to grey-matter atrophy.

A Normative Database from Magnetic Resonance Imaging

Without controversy, magnetic resonance (MR) imaging achieves exquisite approximation of gross anatomy. This has been appreciated from the onset of the se of MR technology to image the brain. However, what has been clinically lacking in the first decade of MR use is a rapid yet automated means to quantify various neuroanatomic structures. As such, much of the interpretation of MR imaging has been based primarily on a qualitative rather than quantitative analysis (see Osborn, 1994).