Nobuhito Morota

Anatomical variants in the floor of the third ventricle; implications for endoscopic third ventriculostomy

Longstanding hydrocephalus and raised intracranial pressure can lead to unusual anatomical variants in the floor of the third ventricle, which may be important when performing endoscopic third ventriculostomy. Two middle aged patients with symptomatic longstanding hydrocephalus had scans that showed ventricular hydrocephalus, an empty sella, and a dilated infundibular recess which herniated into the sella turcica. Endoscopic third ventriculostomy confirmed that instead of the tuber cinerum and infundibular recess, the anterior inferior floor of the third ventricle was hanging down ventral to the pons into the sellar floor. Third ventriculostomy to the prepontine cistern was made on the dorsal wall of the dilated infundibular recess to the area surrounded by the dorsum sellae, the basilar artery trunk, and the left superior cerebellar artery, with good symptomatic control. Association of the empty sella and persistence of the infundibular recess must be carefully evaluated by MRI before attempting endoscopic third ventriculostomy. Herniation of the anterior inferior floor of the third ventricle into the empty sella can lead to loss of anatomical landmarks that require special attention during third ventriculostomy.

Infantile subdural fluid collection: diagnosis and postoperative course

The authors reviewed 47 cases of infantile subdural fluid collection with regard to diagnosis and postoperative course after placement of a subdural-peritoneal shunt. CT scan with contrast enhancement proved to be an important diagnostic modality, showing vessels in the subarachnoid space as high-density spots. Utilizing this technique, we were able to differentiate the following varieties of fluid collection: (1) subdural fluid collection, in which enhancing vessels were seen on the brain surfae, (2) subarachnoid fluid collection, in which vessels were on the inner table of the cranium, and (3) coexistence of subdural and subarachnoid fluid collections, in which vessels were between the inner table of the cranium and the brain surface. The postoperative course of subdural fluid collection was characterized as follows: (1) the subdural fluid collection decreased first, with increased subarachnoid fluid collection; (2) the subarachnoid fluid collection remained after the disappearance of subdural fluid collection; and (3) the brain expanded again later. Subdural fluid collection disappeared about 1 month after the shunt operation, which could lead occlusion of the shunt system. Postoperative enlargement of the subarachnoid space was an early indicator of the efficacy of the subduralperitoneal shunt.

Endoscopic coagulation of choroid plexus as treatment for hydrocephalus: indication and surgical technique

ObjectChoroid plexus surgery, which had been discarded as a treatment for hydrocephalus, was brought back into use with the development of modern neuroendoscopic technology. The object of this article is to describe the author’s experience of the surgery with special emphasis on the surgical indication.MethodsThree infants underwent endoscopic choroid plexus coagulation as a treatment for hydrocephalus. Standard procedure for the surgery was unilateral transparietal insertion of a flexible neuroendoscope and electrical coagulation of the choroid plexus. The results showed the release of increased intracranial pressure in two infants, while the other, whose hydrocephalus was rather progressive, later required a VP shunt.ConclusionChoroid plexus surgery for hydrocephalus seems to be effective in some patients. Advanced modern technology has enabled the application of a neuroendoscope for this procedure. From our limited experience, the key to the success of endoscopic choroid plexus coagulation is the selection of patients. Favorable candidates for the surgery seem to be those who suffer from the slow progressive, severe form of hydrocephalus and who lack the septum pellucidum.

The Use of Motor Evoked Potentials in the Diagnosis of Psychogenic Quadriparesis

We present a case illustrating the usefulness of motor evoked potentials (MEPs) in differentiating psychogenic from organic postoperative paralysis. Discussed is a 12-year-old girl who underwent surgery for the repair of a recurrent syringomyelia. On the 6 day after a proximal revision of her syringoperitoneal shunt she returned to the hospital with deep quadriparesis, bowel and bladder incontinence, and complaining of severe headache. An MRI scan showed the syrinx to be collapsed, and removal of the shunt had no impact on her clinical symptoms. Repeat somatosensory evoked potentials (SEPs) showed no change in comparison to those obtained at the end of her preceding surgery. MEPs were normal for the lower extremities, a finding which is inconsistent with a severe upper motor neuron lesion. She was diagnosed with psychogenic paralysis, and fully recovered within 1 month. We propose that a neurophysiological evaluation including MEPs is useful in the differential diagnosis of psychogenic and organic motor weakness.

Giant aneurysms of the horizontal segment of the anterior cerebral artery: report of two cases.

Two cases of giant aneurysm of the horizontal segment of the anterior cerebral artery (A1) are presented. The rare occurrence of a giant aneurysm in this location necessitates evaluation of the cross-flow through the anterior communicating artery when planning surgical strategy. On the basis of angiographic findings, trapping of the A1 on both sides of the aneurysm neck was performed in Case 1, and aneurysmorrhaphy utilizing an angioplastic multiple-clipping method of A1 endarterectomy was accomplished in Case 2. The postoperative courses of both patients were satisfactory.

Obstructive hydrocephalus due to a giant aneurysm of the internal carotid bifurcation

A rare case of obstructive hydrocephalus associated with a giant aneurysm of the internal carotid artery is presented. The giant aneurysm, which was located in the prepontine cistern, was initially thought to be of basilar artery origin. Cerebral computed angiotomography had the most diagnostic value in disclosing the partially thrombosed giant aneurysm and its relationship with the surrounding arteries. After undergoing a ventriculoperitoneal shunt operation, the patients clinical symptoms markedly improved.

Preserved motor evoked potentials fail to predict functional outcome in quadriplegia because of bilateral lesions of the supplementary motor areas: a brief report.

We present a patient with a lesion of the mesial frontal cortex, including the supplementary motor areas bilaterally, who on clinical examination revealed no spontaneous movements, although neurophysiological examination indicated integrity of the corticospinal tract to thenar and tibialis anterior muscles bilaterally. The patient was alert, speech was hesitant, and he was able to move his hands only on command. The role of the supplementary motor areas in planning, setting, and execution of skillful voluntary movements has been previously established by direct cortical electrical stimulation and studies of regional cerebral blood flow. The findings in our patient support the role of the supplementary motor areas in initiating movements. The presence of motor evoked potentials after acute insults to the brain is considered to be associated with a good functional outcome. This is in contrast to our patient who did not show improvement in motor performance, despite preserved motor evoked potentials. Hence, in the case of bilateral lesions to the supplementary motor areas sparing the corticospinal tract, the presence of motor evoked potentials may not predict functional recovery.

Functional posterior rhizotomy: the Tokyo experience

PurposeThe author describes the history of functional posterior rhizotomy (FPR), the surgical procedure currently used, and the results together with its future perspective in Japan. The modern form of FPR was introduced to Japan in 1995, and the first surgery was carried out in 1996. Despite initial resistance from orthopedic surgeons, the procedure has eventually gained wide recognition in the country.Materials and MethodsThe author has operated on 98 patients (60 boys and 38 girls, aged from 2 to 19xa0years old) by the end of 2006. Most patients were mild to severely disabled children with spastic hypertonia because of cerebral palsy and other diseases. The surgical procedure used is based on the Peacock’s procedure with some modification for the mildly disabled children whose spasticity was predominantly the muscles of the ankle joint. Intraoperative neurophysiology was an indispensable tool for preserving urogenital function and for judging which root/rootlet to be cut.ResultsSeventeen to 83% of the root/rootlets were found to be abnormal and were cut, clearly correlating with the degree of disability. However, there was a wide difference in the cutting rate, even in children with the same degree of disability. The result of surgery in this group of patients was the same as in previously published data. Twenty out of 51 patients (39%) followed for more than a year at the current institute showed improved locomotion after FPR. Thirty patients (59%) demonstrated suprasegmental effects after FPR.ConclusionThe role of FPR will grow in importance as a treatment for spasticity in Japan in the future.

Pediatric high-flow, cervical spinal, macro-arteriovenous fistula, treated with the endovascular cotton candy glue injection technique

Case reportA 3-year-old boy presented to our hospital with progressive neurological deficits. Spinal magnetic resonance imaging (MRI) revealed a perimedullary macro-arteriovenous fistula (PMAVF) resulting in a large venous pouch within the parenchyma of the lower cervical spinal cord.Transarterial varix embolization of the fistula from the venous side was performed using N-butyl cyanoacrylate with tantalum powder. Postembolization angiography confirmed obliteration of the fistula, and MRI revealed thrombosis and reduction in size of the venous component. The patient’s clinical symptoms were reduced dramatically following the intervention, and no neurological complications occurred due to the treatment. The prognosis of spinal PMAVF depends primarily on the presence of medullar signs and symptoms and on time to treatment. The volume of the venous pouch after the intervention was markedly reduced, and complete clinical recovery was obtained. Urgent endovascular intervention, as seen in this case, is considered first-line therapy and aims to decrease the risk of neurological sequela.

Approximation of the Split Brain Surface in an Infant with Schizencephaly and Multiple Brain Anomalies

The authors reported an infant with schizencephaly and multiple brain anomalies. The schizencephaly was treated by approximating the two surfaces of the brain defect with intermittent sutures, which we called “cerebrorrhaphy.”