[Follow-up studies on 40 cases of posttraumatic subdural hygromas -- the development of the chronic subdural hematomas (author's transl)]

Traumatic subdural hygroma and chronic subdural hematoma: A systematic review and meta-analysis

Recently, a relationship between traumatic subdural hygroma (SDG) and chronic subdural hematoma (CSDH) has been proposed. However, the role of traumatic SDG in development of CSDH has not been well characterized. This systematic review aimed to estimate the rate of evolution of traumatic SDG to CSDH, and to identify risk factors associated with traumatic SDG evolution to CSDH. We searched MEDLINE, EMBASE, and Cochrane Library databases from inception to May 26, 2021, using the combination of the terms "subdural hygroma" and "chronic subdural hematoma." Using a random-effects model, we calculated a pooled estimate of rate of evolution of traumatic SDG to CSDH. In addition, we conducted a systematic review of studies of risk factors for traumatic SDG evolution to CSDH. Nineteen studies with 1,335 patients met the inclusion criteria for meta-analysis. The pooled estimate of evolution rate was 25.0 % (95 % CI, 19.3 %-30.7 %; I² = 85.6 %), with significant heterogeneity among studies (P < 0.01). Age ≥ 60 years was associated independently with traumatic SDG evolution to CSDH, after adjustment for study design using multivariate meta-regression. Risk factors associated with evolution of traumatic SDG to CSDH were radiological characteristics such as thicker SDG and higher SDG CT value. The rate of traumatic SDGs evolution to CSDH is approximately 25 %. Patients aged 60 or older with traumatic SDGs are at increased risk of CSDH development. Thicker SDG and higher SDG CT value, are commonly reported risk factors for traumatic SDG evolution to CSDH. However, higher quality studies are needed.

Age determination of subdural hematomas with CT and MRI: a systematic review

OBJECTIVES

To systematically review the literature on dating subdural hematomas (SDHs) on CT and MRI scans.

METHODS

We performed a systematic review in MEDLINE, EMBASE and Cochrane to search for articles that described the appearance of SDHs on CT or MRI in relation to time between trauma and scanning. Two researchers independently screened the articles, assessed methodological quality and performed data extraction. Medians with interquartile ranges were calculated. Differences were tested with a Mann-Whitney U or Kruskal-Wallis H test.

RESULTS

We included 22 studies describing 973 SDHs on CT and 4 studies describing 83 SDHs on MRI. Data from 17 studies (413 SDHs) could be pooled. There were significant differences between time intervals for the different densities on CT (p<0.001). Time interval differed significantly between children and adults for iso- and hypodensity (p=0.000) and hyperdensity (p=0.046). Time interval did not differ significantly between abused and non-abused children. On MRI, time intervals for different signal intensities on T1 and T2 did not differ significantly (p=0.108 and p=0.194, respectively).

CONCLUSIONS

Most time intervals of the different appearances of SDHs on CT and MRI are broad and overlapping. Therefore CT or MRI findings cannot be used to accurately date SDHs.

Identification of 7 alpha-hydroxy-3-oxo-4-cholestenoic acid in chronic subdural hematoma

We detected a novel kind of bile acid in the content of chronic subdural hematoma. This substance was specifically found in chronic subdural hematoma, and not in subdural hygroma, which is pathologically similar except for the lack of capsular membrane. The compound was identified as 7 alpha-hydroxy-3-oxo-4-cholestenoic acid by high performance liquid chromatography, gas chromatography-mass spectrometry, and nuclear magnetic resonance spectrometry. The structure was confirmed by the comparison with the chemically synthesized compound. The average contents in chronic subdural hematoma were 658.09 +/- 137.53 ng/ml, while those in normal human plasma were 126.27 +/- 17.73 ng/ml. It was not detected in normal cerebrospinal fluid. The higher level in chronic subdural hematoma than human plasma strongly suggests the local, extrahepatic production of this type of C27 bile acids.

Protein analysis of subdural hygroma fluid

The pathogenesis of posttraumatic subdural hygroma still remains largely unknown. One of the suggested pathological mechanisms is the traumatic development of an arachnoid tear and the subsequent efflux of CSF into the subdural space. We performed a multifactorial analysis of the hygroma fluid obtained at operation in comparison to the simultaneously taken plasma and lumbar CSF. The results of the protein analysis support the CSF origin of the subdural hygroma fluid.

The clinical course of surgically treated posttraumatic subdural hygromas

The clinical course of 11 patients with a subdural hygroma, who underwent neurosurgery, was studied. In the first week after the operation no improvement of the mental status could be detected. We considered therefore that operation hardly contributed to improvement. Thus the need to operate is limited to special cases such as acute or space-occupying subdural hygroma.