Tag: Pathogenesis

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The Danish Chronic Subdural Hematoma Study—comparison of hematoma age to the radiological appearance at time of diagnosis

Acta Neurochirurgica (2020) 162:2007–2013

Chronic subdural hematomas (CSDH) show different radiological characteristics on CT scans at the time of diagnosis. The reason for this is largely unknown. We hypothesize that the imaging characteristics reflect a time-linked pathophysiological evolution. We therefore conducted a retrospective study to examine a possible relation between the hematoma age and the radiological subtype of a CSDH.

Methods Demographic data on patients with CSDH were retrieved from a Danish national cohort from 2010 to 2012. CT scans obtained on admission to a neurosurgical department were categorized as homogenous, separated, mixed, or membranous hematoma subtypes. The time from a known date of head injury to time of diagnostic CT was defined as hematoma age. The hematoma age was correlated to radiological hematoma subtype at the time of diagnosis by analysis of variance testing.

Results In total, 543 patients were analyzed for hematoma age and classified in the following hematoma subtypes: 231 homogenous, 44 separated, 119 mixed, and 149 membranous. Patients with homogenous, separated, mixed, and membranous hematoma subtypes had a median interval of 37, 36, 40, and 60 days from head injury to diagnostic CT. We found that membranous hematoma is significantly older than other subtypes. Comparison between the other radiological subtypes showed no statistical hematoma age difference. The distribution of radiological subtypes in 590 patients without a known head injury was similar to that of patients with a known head injury. Additionally, we found that hematoma age was significantly younger for patients on antiplatelet medication.

Conclusion In this large national cohort, patients with membranous CSDH had a significantly longer interval between head injury and diagnosis compared to other radiological subtypes. This indicates that the radiological appearance of CSDH evolves over time, causing an alteration from different early radiological subtypes to a radiological subtype with membranes.

Clinical trial registration number The study was approved by the Danish Data Protection Agency (journal no.30-1145).

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Pathogenesis of syringomyelia associated with Chiari type 1 malformation: review of evidences and proposal of a new hypothesis

Neurosurg Rev (2010) 33:271–285. DOI 10.1007/s10143-010-0266-5

The exact pathogenesis of syringomyelia associated with Chiari type 1 malformation is unknown, although a number of authors have reported their theories of syrinx formation. The purpose of this review is to understand evidences based on the known theories and to create a new hypothesis of the pathogenesis. We critically review the literatures on clinicopathological, radiological, and clinical features of this disorder.

The previously proposed theories mainly focused on the driven mechanisms of the cerebrospinal fluid (CSF) into the spinal cord. They did not fully explain radiological features or effects of surgical treatment such as shunting procedures.

Common findings of the syrinx in clinicopathological studies were the communication with the central canal and extracanalicular extension to the posterior gray matter. Most of the magnetic resonance imaging studies demonstrated blockade and alternated CSF dynamics at the foramen magnum, but failed to show direct communication of the syrinx with the CSF spaces.

Pressure studies revealed almost identical intrasyrinx pressure to the subarachnoid space and decreased compliance of the spinal CSF space.

Recent imaging studies suggest that the extracellular fluid accumulation may play an important role. The review of evidences promotes a new hypothesis of syrinx formation. Decreased absorption mechanisms of the extracellular fluid may underlie the pathogenesis of syringomyelia. Reduced compliance of the posterior spinal veins associated with the decreased compliance of the spinal subarachnoid space will result in disturbed absorption of the extracellular fluid through the intramedullary venous channels and formation of syringomyelia.

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