✓ The pathological process of extracerebral fluid collections in infancy includes subdural effusion and enlargement of the subarachnoid spaces. Both conditions have traditionally been investigated as a single clinical entity, because of difficulty in differentiating between them. The prognosis of subdural effusion is not as benign as that of enlargement of subarachnoid spaces, requiring differential diagnosis between these disorders. The present study was conducted to elucidate whether this differentiation could be made on magnetic resonance (MR) images.
The series consisted of 16 infants aged 10 months or younger, including eight with verified subdural effusion and eight in whom a diagnosis of enlargement of the subarachnoid spaces was achieved by neuroimaging studies other than MR imaging. In all eight patients with subdural effusion, the intensity of the fluid was greater than that of cerebrospinal fluid (CSF) in at least one of the sequences using T1-weighted, proton-density, and T2-weighted MR images. The flow-void sign, indicating vessels in the fluid spaces, was not seen in any of these eight patients. On the other hand, in all eight patients with enlargement of the subarachnoid spaces, the fluid was isointense in relation to CSF, and vascular flow-void areas were seen in at least one of the MR imaging sequences. Based on these observations, it is concluded that differentiation between subdural effusion and enlargement of the subarachnoid spaces can be established by focusing on two aspects of MR imaging findings: 1) the intensity of the fluid, which is either iso- or hyperintense relative to CSF, and 2) the presence or absence of vascular flow-void areas in the fluid spaces.
Kazuo Tsutsumi, Yoshiaki Shiokawa, Tatsuo Sakai, Nobuhiko Aoki, Masaru Kubota and Isamu Saito
✓ Postoperative venous infarction following aneurysm surgery was studied in 48 patients with anterior communicating artery aneurysms operated on through the interhemispheric approach at the acute stage of subarachnoid hemorrhage (SAH). Of 23 patients whose bridging veins were sacrificed during surgery, 11 (47.8%) showed venous infarction in the frontal lobes. In contrast, only one (5.9%) of 17 patients whose bridging veins were preserved developed cerebral edema. None of eight patients who were operated on after Day 11 (the day of SAH was defined as Day 0) showed this complication, although bridging veins were sacrificed in six of them. Venous infarction following acute aneurysm surgery tended to occur more frequently in patients of higher SAH grade and/or more advanced age, but these correlations were not significant. However, the correlation between the sacrifice of veins and venous infarction was significant (p < 0.025). Because this potential complication may compromise the benefit of acute aneurysm surgery and cause damage, it is important to preserve the venous system and in some instances to select another surgical approach based on the pattern of venous drainage in the frontal lobe.
Clinical analysis of 30 cases in the CT era
✓ The cases of 30 infants with chronic subdural hematoma treated surgically between 1978 and 1987 (after the introduction of computerized tomography) were reviewed. This series was limited to infants presenting with increased intracranial pressure, neurological deficits, or developmental retardation. Nineteen patients were male and 11 were female, ranging in age from 1 to 14 months (average 6.1 months). The surgical treatment was initiated with percutaneous subdural tapping which was repeated periodically, if indicated, for 2 weeks. If the patients failed to respond to subdural tapping, subdural-peritoneal shunting was installed. The follow-up periods were from 3 months to 9 years 8 months (average 4 years 10 months). Computerized tomography at that time disclosed disappearance or minimal collection of subdural fluid in 28 cases (93%) and a significant collection (> 5 mm) in two (7%). Neurological examination revealed that the patients were “normal” in 17 cases (57%), “mildly or moderately disabled” in nine (30%), and “severely disabled” in four (13%). The majority of disabled patients had lesions secondary to infantile acute subdural hematoma, child abuse, or hemorrhagic diathesis.
These results indicate that the treatment protocol in the present series is acceptable for the elimination of subdural hematoma. Together, early diagnosis and treatment of the etiological conditions causing the lesion are indispensable for obtaining a satisfactory neurological outcome.