Revisiting Grade 3 Diffuse Axonal Injury: Not All Brainstem Microbleeds are Prognostically Equal.

BACKGROUND: Recovery of functional independence is possible in patients with brainstem traumatic axonal injury (TAI), also referred to as "grade 3 diffuse axonal injury," but acute prognostic biomarkers are lacking. We hypothesized that the extent of dorsal brainstem TAI measured by burden of traumatic microbleeds (TMBs) correlates with 1-year functional outcome more strongly than does ventral brainstem, corpus callosal, or global brain TMB burden. Further, we hypothesized that TMBs within brainstem nuclei of the ascending arousal network (AAN) correlate with 1-year outcome. METHODS: Using a prospective outcome database of patients treated for moderate-to-severe traumatic brain injury at an inpatient rehabilitation hospital, we retrospectively identified 39 patients who underwent acute gradient-recalled echo (GRE) magnetic resonance imaging (MRI). TMBs were counted on the acute GRE scans globally and in the dorsal brainstem, ventral brainstem, and corpus callosum. TMBs were also mapped onto an atlas of AAN nuclei. The primary outcome was the disability rating scale (DRS) score at 1 year post-injury. Associations between regional TMBs, AAN TMB volume, and 1-year DRS score were assessed by calculating Spearman rank correlation coefficients. RESULTS: Mean ± SD number of TMBs was: dorsal brainstem = 0.7 ± 1.4, ventral brainstem = 0.2 ± 0.6, corpus callosum = 1.8 ± 2.8, and global = 14.4 ± 12.5. The mean ± SD TMB volume within AAN nuclei was 6.1 ± 18.7 mm3. Increased dorsal brainstem TMBs and larger AAN TMB volume correlated with worse 1-year outcomes (R = 0.37, p = 0.02, and R = 0.36, p = 0.02, respectively). Global, callosal, and ventral brainstem TMBs did not correlate with outcomes. CONCLUSIONS: These findings suggest that dorsal brainstem TAI, especially involving AAN nuclei, may have greater prognostic utility than the total number of lesions in the brain or brainstem.

Reversible sensorineural hearing loss with normal brainstem auditory evoked potentials in pontine hemorrhage due to capillary telangiectasia.

Capillary telangiectasias are vascular malformations most commonly found in the pons that are rarely associated with hemorrhage. We describe a unique case of pontine capillary telangiectasia causing central brainstem hemorrhage leading to reversible sensorineural deafness associated with a normal brainstem auditory evoked response.

MR imaging of midbrain pathologies.

The spectrum of pathologic processes affecting the midbrain features some differences to other brain areas. The midbrain is exposed to traumatic alterations due to its position between the tentorial edges, and some neurodegenerative and metabolic-toxic diseases may typically involve the midbrain. Isolated midbrain ischemia is rare, whereas the midbrain is typically part of the "top of the basilar" syndrome. Primary midbrain tumors are also infrequent and often show a benign clinical course. Apart from multiple sclerosis other inflammatory autoimmune processes and some infectious agents predominantly affect the brainstem including the midbrain. This review discusses the different pathologic processes of the midbrain, i.e., infarction, hemorrhage and trauma, inflammation, toxic and metabolic diseases, neurodegeneration, neoplastic diseases, as well as pathologies typically involving the perimesencephalic cisterns.

Brainstem hemorrhage in descending transtentorial herniation (Duret hemorrhage).

OBJECTIVES: To review clinical and radiological findings in patients with Duret hemorrhages and to discuss the pathophysiology and differential diagnosis of these lesions. PATIENTS AND METHODS: We reviewed the case records of four patients with Duret hemorrhages who had been admitted to the neurological intensive care unit with supratentorial mass lesions. RESULTS: Descending transtentorial and subfalcine herniations were present in all cases. Three patients were admitted with acute subdural hematoma and one with intraparenchymal hemorrhage. Computed tomography revealed the presence of blood in the mesencephalon and upper pons. Three patients died; one survived with severe disabilities. DISCUSSION: Duret hemorrhages are typically located in the ventral and paramedian aspects of the upper brainstem (mesencephalon and pons). The pathophysiology of Duret hemorrhage remains under debate: arterial origin (stretching and laceration of pontine perforating branches of the basilar artery), versus venous origin (thrombosis and venous infarction). Multifactorial causation seems likely. CONCLUSION: Duret hemorrhages are delayed, secondary brainstem hemorrhages. They occur in craniocerebral trauma victims with rapidly evolving descending transtentorial herniation. Diagnosis is made on computed tomography of the brain. In most cases the outcome is fatal. On the basis of our observations we believe that arterial hypertension and advanced age are risk factors for the development of Duret hemorrhage.