Yoshitaro Yamaguchi

Comparative Study of Magnetic Resonance and CT Scan Imaging in Cases of Severe Head Injury

The distribution, frequency, and appearance of head injuries were evaluated with MRI and CT in a prospective study of 155 patients with acute (n = 124) and chronic (n = 31) head injuries. MRI was significantly more sensitive than CT in the detection of intraaxial injury at any stage. In severe cases, central structure lesions were detected in approximately 80% of patients. Severity on admission was compatible with MR findings. However it was difficult to decide on neurobehavioural prognosis from initial MRI findings only.

Frontotemporal orbitozygomatico-alar approachfor skull surgery

Mobilisation of the zygoma has been reported to offer excellent exposure of the cranial base with minimal brain retraction. This study describes our operative technique and presents our experiences of 22 patients. Fifteen patients had a skull base neoplasm and 7 had a complex cerebral aneurysm. To facilitate access to these lesions, two separate bone flaps were created: (1) A free frontotemporal bone flap; and (2) en bloc removal of the superior and lateral orbital rims with the attached zygomatic arch. Because the latter bone flap includes both the orbital roof and the posterolateral wall of the orbit with the greater wing of the sphenoid bone, unnecessary bony defects which could cause enophthalmos or other cosmetic problems are avoided. Among the 22 patients, 17 have returned to their previous life style and four require assistance for personal care. Operative mortality was zero. The incidence of postoperative complications directly related to this approach was minimal and cosmetic results were acceptable in most patients. We recommend this approach for medially located skull base neoplasms or complex cerebral aneurysms.

Evolution from Acute Subdural Hematomas to Chronic Subdural Hematomas

We analyzed 52 patients of acute subdural hematoma treated conservatively because of mild clinical symptoms and/or thin subdural hematoma to elucidate the evolution from acute subdural hematomas to chronic subdural hematomas. Based on the follow-up CT findings, these patients were classified into two groups: subdural hematomas increased in size gradually with or without deterioration of clinical manifestations(group 1) and subdural hematomas disappeared spontaneously(group 2). Group 1 included 23 patients. In most patients, CT showed the increase in size with a decrease in hematoma density 8 to 14 days after the insult. Fifteen patients were treated with a burr hole craniectomy and the evacuation of liquid hematoma content because of a deterioration of signs and symptoms. Average time elapsed to be operated was 26 days. The neomembrane similar to the outer membrane of chronic subdural hematomas was verified in 11 out of 15 operated patients. These neomembrane could not be differentiated from that of ordinary chronic subdural hematomas pathohistologically. The average age in 29 patients of group 2 was younger than that of group 1. Despite variable changes in hematoma density, subdural hematomas in group 2 decreased in size gradually or rapidly, and eventually disappeared. Average time elapsed to disappear was 25 days. When chronic subdural hematomas are defined as chronically enlarged and encapsulated subdural hematomas, a part of group 1 is considered to be chronic subdural hematomas and the evolution from acute subdural hematomas to chronic subdural hematomas can be present.