Motoaki Fujii

Thalamic neuronal hyperactivity following transection of the spinothalamic tract in the cat: involvement ofN-methyl-d-aspartate receptor

Single neuron activities responding to peripheral stimuli with short latencies were recorded within the thalamic nucleus ventralis posterolateralis (VPL) after transection of the spinothalamic tract (STT) in the cat under alpha-chloralose anesthesia. The VPL neurons showed spontaneous and evoked hyperactivity after STT transection, which was revealed at 1-2 weeks. The spontaneous hyperactivity further progressed until 3-4 weeks. These hyperactivities were observed in core-area neurons as well as neurons found in the shell area, suggesting that some, if not many, of the N-methyl-D-aspartate (NMDA) receptor antagonist (MK-801, 4-16 mg; i.v.) attenuated both the spontaneous and evoked hyperactivity observed after STT transection. No such effects were demonstrated in sham-operated animals. These findings suggest that VPL neurons become hyperactive after STT transection through recruitment of NMDA receptors. The hyperactivity of VPL neurons may represent an important background process in the production of deafferentation pain induced by lesions involving the STT.

Dynamic changes in cytochrome oxidase activity in the rat somatosensory cortex following thalamocortical deafferentation

The changes in cytochrome oxidase (CYO) activity in the primary somatosensory cortex (SI) induced by unilateral lesions restricted to the posterior ventrobasal region of the thalamus were investigated by histochemical techniques and photometric semi-quantitation in the rat. The CYO activity decreased rapidly and dramatically in layer IV of the lesioned side, reaching its lowest level within 2 weeks, and remained depressed at 8 weeks post-lesion. Segmentations normally seen in layer IV corresponding to barrels remained absent. While less marked decreases were also noted in other layers, obvious recovery was subsequently observed, attaining levels comparable to those on the intact size at 6 or 8 weeks post-lesion. The persistent decrease in layer IV appears to reflect a reduced thalamocortical activation of the dendritic profiles and neuronal perikarya. The recovery in other layers may represent an increase in the resting level of the initially depressed neuronal activity near to the original levels. The persistent reduction of function in the inhibitory surround, which is normally activated by thalamocortical input, may contribute to the increase in CYO activity.

Inguinal bladder hernia: multi-planar reformation and 3-D reconstruction computed tomography images useful for diagnosis.

We present a case of inguinal bladder hernia that was preoperatively diagnosed with the aid of multi-planar reformation (MPR) and 3-D reconstruction computed tomography (CT) (Figs 1,2) and confirmed with surgery. While CT is a useful tool, reported CT findings are not consistently observed. To make the diagnosis with certainty, an oblique sagittal MPR CT image which is reconstructed along the inguinal canal by volume data (1 mm slice thickness) was completed and shows clear visualization of the continuity from the bladder to the hernia (arrow). 3-D reconstruction CT imaging by volume rendering shows the herniated bladder situated lateral to the inferior epigastric artery (arrow). This is useful in demonstrating its exact location and its relationship with the surrounding structures such as the inferior epigastric vessels, as shown in our case.

Spontaneously Disappearing Acute Subdural Hematomas: Conservative Treatment with Intracranial Pressure Monitoring

It has become increasingly clear that the acute thin subdural hematomas detected in the very early period following trauma can disappear spontaneously within a day [1–6]. We have experienced 10 cases of such hematomas since our initial reports [3]. It seems that the earlier the initial CT scan is taken, the more frequently such hematomas are encountered.

Near-Infrared Spectroscopy at the Sagittal Sinus Region: Comparison with Jugular Bulb Oxymetry

Since the first clinical application during the 1940s [1, 2], infrared spectroscopy has become an important clinical technique through the development of a pulsed oxymeter [3]. More recently, near-infrared intracranial spectroscopy (NIS) has been introduced as a technique to monitor oxygenation of the brain noninvasively [4]. The NIS device is usually placed on the scalp of the forehead so that oxygenation of the frontal lobe at the depth of 2.5 cm is monitored [5–8]. Because the total blood volume of the brain consists of 75% venous blood, data from NIS can be regarded as reflecting the balance of oxygen supply and consumption [9, 10]

Oedema fluid clearance within cerebral contusion studied by MRI

Peripheral oedema associated with cerebral contusion is life-threatening in severe head injury. The present study was conducted to make clear the time sequence of development of post-traumatic vascular permeability using gadolinium (Cd)-DTPA-enhanced MRI. We examined 10 patients with traumatic cerebral contusion (mean age 38 years; 8 men and 2 women) with Gd-DTPA-enhanced MRI 1-3 days after head trauma. Gad-olium-DTPA (0.3mmol/Kg) was administered by intravenous drip infusion for 30 min. MRI was performed before, and 2 and 4 h after infusion. The contusional oedema area frequently enhanced with Gd-DTPA 2 h after infusion. After 4 h, the enhancement had already begun to decrease. These findings suggest that increased vascular permeability in the very acute phase of head injury may contribute in part to the formation of contusional oedema and that the oedema fluid clearance within cerebral contusion is more rapid than previously thought.

Rapid Spontaneously Disappearance of Acute Subdural Hematomas: Analysis of 31 Cases

We reviewed 31 cases of acute thin subdural hematomas including those reported in the literature and our own which had disappeared spontaneously within 72 hours post-trauma. The subdural hematomas in these cases were detected mostly within 60 min after injury. A significant decrease in hematoma size was demonstrated at as early as 2 hours after injury. It seems therefore that the earlier the initial CT scan was taken, the more frequently acute thin subdural hematomas which rapidly disappeared could be detected. The hematomas did not explain clinical conditions on admission. Brain swelling and cardiorespiratory failure appeared to be responsible for poor outcome. Repeated CT scans and careful observation of the neurological changes is recommended before undertaking surgical intervention in such cases.