Yoshihiro Minamida

Cranial nerve assessment in posterior fossa tumors with fast imaging employing steady-state acquisition (FIESTA)

Steady-state free precession is widely used for ultra-fast cardiac or abdominal imaging. The purpose of this work was to assess fast imaging employing steady-state acquisition (FIESTA) and to evaluate its efficacy for depiction of the cranial nerve affected by the tumor. Twenty-three consecutive patients with posterior fossa tumors underwent FIESTA sequence after contrast agent administration, and then displacement of the cranial nerve was evaluated. The 23 patients with posterior fossa tumor consisted of 12 schwannomas, eight meningiomas, and three cases of epidermoid. Except in the cases of epidermoid, intensity of all tumors increased on FIESTA imaging of the contrast enhancement. In the schwannoma cases, visualization of the nerve became poorer as the tumor increased in size. In cases of encapsulated meningioma, all the cranial nerves of the posterior fossa were depicted regardless of location. The ability to depict the nerves was also significantly higher in meningioma patients than in schwannoma patients (P<0.05). In cases of epidermoid, extension of the tumors was depicted clearly. Although the FIESTA sequence offers similar contrast to other heavily T2-weighted sequences, it facilitated a superior assessment of the effect of tumors on cranial nerve anatomy. FIESTA sequence was useful for preoperative simulations of posterior fossa tumors.

Superior oblique myokymia caused by vascular compression.

A 49-year-old man had left superior oblique myokymia for eight years. Magnetic resonance images with enhanced spoiled gradient recalled acquisition in the steady state (SPGR) and flow imaging using steady acquisition (FIESTA) disclosed a branch of the superior cerebellar artery lying on the root exit zone of the left trochlear nerve. Posterior fossa craniotomy confirmed the imaging findings. A Teflon pad was placed between the compressing artery and the trochlear nerve. The patients superior oblique myokymia has completely resolved with a one-year follow-up. Only one such case has been previously reported. This is the first report to display the imaging findings.

Quantitative analysis of adverse events in neurosurgery.

OBJECTIVE:It is well recognized that the occurrence rate of adverse events related to surgical procedures is considerably high in neurosurgery compared with other specialties. The purpose of this study was to quantitatively determine the occurrence rate of adverse events related to surgery and endovascular intervention in neurosurgery. METHODSA conference on adverse events related to treatments (morbidity and mortality conference) has been held every month for the past 2 years in our department. At these conferences, all adverse events are evaluated and discussed. Adverse events include not only the unexpected complications, but also the neurological and general deterioration predicted before surgery. All the adverse events are discussed in terms of the conceivable causes, their association with the procedures, and the possibility of prediction and avoidance. RESULTSOne hundred eighty-two events (28.3%) among 643 neurosurgical interventions over 2 years were recognized as adverse events. Among these 182 adverse events, 165 (90.7%) were closely related to procedures and 125 events (68.7%) were predictable before or during the procedures. However, even when retrospectively reviewed, only 6 (3.3%) of events were deemed avoidable. Of these 6 avoidable events, there were only 2 (1.1%) that were considered to have been caused by error. CONCLUSIONAdverse events are not invariably rare in neurosurgery. Most of them are predictable; however, their avoidance is not necessarily easy. Avoidable adverse events caused by medical errors were observed in only 1.1% of cases.

Glioblastoma simultaneously present with adjacent meningioma: case report and review of the literature

The simultaneous occurrence of multiple primary intracranial tumors has been reported previously. However, most of these tumors arise after cranial radiotherapy or in association with familial tumor syndromes. Double tumors of different histologies that are unrelated to radiotherapy or genetic disorders are very rare. We present a case of two primary intracranial tumors occurring simultaneously at adjacent sites. Preoperative gadolinium-enhanced magnetic resonance imaging of these tumors revealed a single continuous lesion. Postoperative histological examination revealed the presence of two distinct tumors, meningioma and glioblastoma multiforme. To elucidate the mechanism of synchronous tumor formation, we performed immunohistochemical analysis of the proteins involved in the receptor tyrosine kinase, Wnt, and Notch signaling pathways. These analyses showed that platelet-derived growth factor (PDGF) receptors-α and β were overexpressed in both tumors, thereby indicating the oncogenic effects of activated signaling of these receptors. The PDGF-mediated paracrine system may induce one tumor from another.

Novel bipolar forceps with protein repellence using gold-polytetrafluoroethylene composite film.

OBJECTIVE Advancement in new technology has been necessary for the development of surgical hemostasis. The purpose of this study was to assess novel bipolar forceps plated with gold-polytetrafluoroethylene (PTFE) composite film. METHODS Novel bipolar forceps with gold–PTFE composite film were invented and compared with commercially available forceps with 50-μm gold-plated tips in terms of their physical properties and coagulation performance. The contact angle was measured to determine the degree of wetting tension. Then the surface roughness, electric resistance, and changes in local temperature on the surface of the tip were recorded. Coagulation performance of the two sets of bipolar forceps was determined comparing the amount of protein in the adhered coagulum on the tips and comparing the ease with which the coagulum could be removed. RESULTS This gold–PTFE composite film-plated metal has a significantly higher contact angle than conventional gold-plated metal, and the plating maintains the matrix metal property. The amount of coagulum sticking was smaller than with the ordinary gold-plated forceps. The ease of removal was also superior with the gold–PTFE composite film-plated forceps. CONCLUSION The concept of promotion of protein repellence is important for achieving reduced adherence of protein to neurosurgical instruments. This protein repellent plating is indispensable to achieve safer and more accurate microneurosurgery.

Resolution of superior oblique myokymia following microvascular decompression of trochlear nerve

A 67-year-old man was suffering from a microrotary deviation of the left eye for more than 11 years. He had difficulty fixating from the onset. 8 years after onset he was diagnosed with SOM. He was also treated with carbamazepine, phenytoin and baclofen, but his symptoms were not resolved. On admission, he had continuous unilateral, tonic intorsional nystagmus and phasic oscillations of the left eye. The nystagmus was reinforced when he gazed down. Symptoms were exacerbated by stress and fatigue. With the patient prone, his head was rotated to the right and an occipital interhemispheric transtentorial approach was performed. After opening the quadrigeminal cistern, the origin of the trochlear nerve was revealed to be held suspended by the branch of the SCA (superior cerebellar artery) (diameter <1 mm). The thinnest part of the nerve was located 1.2 mm from the exit point and was twisted 90 degrees. Here, the REZ was compressed at the ventral side of the nerve (Fig. 1). In this case, the compressing small branch was from the caudal trunk of the SCA. By fixing the distortion of the caudal trunk at the proximal portion using Teflon felt, the position of the vessel was shifted distal from the REZ, and the suspended trochlear nerve was loosened (Fig. 1). In this case, it was only possible to shift the compressing vessel 1 mm distally because the branch leading to the brainstem had become stretched and came close to being cut. Involuntary rotary eye movement disappeared completely just after the operation, and there was no postoperative neurological deficit. The patient has had no recurrence for 18 months.

Interstitial spinal-cord oedema in syringomyelia associated with Chiari type 1 malformations

Object: The pathophysiology of syringomyelia in Chiari type 1 malformations has not been clarified. Oedema-like spinal-cord swelling was recently reported in several pathological conditions, including Chiari type 1 malformations as a pre-syrinx state. However, the role of the pre-syrinx state in the development of syringomyelia is unknown. The purpose of this study is to investigate the parenchymal changes of the spinal cord in syringomyelia associated with Chiari type 1 malformations. Methods: Pre- and postoperative MRI findings in 14 patients who underwent foramen magnum decompression in our institute were reviewed. The analysis was focused on differences in visualisation of the syrinx between T1- and T2-weighted images and abnormal parenchymal signal changes. There were 6 men and 8 women, aged from 6 to 79 years. No patients showed hydrocephalus. Results: Twelve patients had large and expansive syrinx, whereas 2 patients showed small syrinx confined to the centre of the spinal cord. T2-weighted images displayed significantly larger intramedullary abnormal signal areas. Nine patients showed parenchymal hyperintensity areas around the enlarged central canal or base of the posterior white columns adjacent to the syringomyelic cavity. Such parenchymal hyperintensity areas markedly diminished with reduction of the syrinx after surgery and were considered to be interstitial oedema. Conclusions: From this study, the interstitial oedema of the spinal cord commonly accompanies syringomyelia with Chiari type 1 malformations. Accumulation of the extracellular fluid due to disturbed absorption mechanisms may play an important role in the pathophysiology of syringomyelia associated with Chiari type 1 malformations.

Free Flap Transfer for the Treatment of Intractable Postcraniotomy Subdural Empyemas and Epidural Abscesses

OBJECTIVE Postcraniotomy subdural empyemas and epidural abscesses are uncommon, potentially lethal, complications of neurosurgery. Patients with these complications may be difficult to manage, and mortality can occur. METHODS Between 1997 and 2006, the authors treated eight patients with recalcitrant postcraniotomy subdural empyema and epidural abscess with combinations of myocutaneous free flap transfer. The free flap transfer was intended for patients who could not be cured with conventional surgical debridement and bone flap removal. Patient ages ranged from 15 to 67 years (mean, 41.5 yr). There were six men and two women. Treatment was required for cranial base tumors (n = 3), the result of trauma (n = 2), malignant tumors (n = 2), and cerebral hematoma (n = 1). In six patients (75%), an expanded polytetrafluoroethylene sheet was used as a dural substitute at the original surgery. We used three rectus abdominis myocutaneous flaps and five latissimus dorsi myocutaneous flaps. In six patients (75%), surgery was performed in the chronic stage of infection, and the other two patients were in the acute stage of infection. RESULTS Among all the patients, two failures occurred because of flap ischemia, but these were resolved after an additional procedure. However, one of these two patients, in whom surgery was performed at the acute stage of infection, died 4 weeks after the surgery. The postoperative course of the other six patients was uneventful. Isolated microorganisms were methicillin-resistant Staphylococcus aureus (four patients), Pseudomonas aeruginosa (three patients), and methicillin-sensitive Staphylococcus aureus (one patient). CONCLUSION Myocutaneous free flap transfer allows sufficient blood circulation and dead space control and is resistant to infection. Therefore, free flap transfer is useful for eliminating intractable empyema and abscess; however, it is important that the procedure be considered in the chronic stage of infection.

Cushing's disease developing independently from acute lymphoblastic leukemia.

To the Editor: Cushing’s disease (CD) is a rare disorder especially in childhood and adolescence [1]. New patients develop at a rate of 1.2–1.7 per million population per year and the median age is 41.4 y with a female: male ratio of 2.7:1 [2]. Although Cushing’s syndrome (CS) occasionally complicates central nervous system (CNS) leukemia [3–5], the association between CD and leukemia has seldom been reported. An 18-y-old male was referred to our hospital because of pathologic bone fracture of the spine. When he was 12-y-old, he developed acute lymphoblastic leukemia (ALL) and received chemotherapy. Four years after completing chemotherapy, his body weight increased rapidly. On admission, he showed stigmata of CD such as central obesity, moon face, hirsutism, buffalo hump, purple skin striae and lower extremity edema. Laboratory findings showed hyperglycemia, alkalotic hypokalemia, elevated ACTH and cortisol (Table 1). Bone marrow and cerebrospinal fluid examination showed no recurrence of ALL. The basal plasma ACTH and serum cortisol levels were elevated and the circadian rhythm was disrupted (Table 2). Dexamethasone suppression test failed to decrease plasmaACTH and cortisol (Table 2). Corticotrophinreleasing hormone administration induced the overexpression of ACTH and cortisol (Table 2). Whole body computed tomography showed no adrenal mass, however magnetic resonance imaging of the brain revealed a 4 mm pituitary adenomatoid mass (Fig. 1). CD due to a pituitary adenoma was confirmed by transsphenoidal surgery, and the ACTH and cortisol levels rapidly normalized within 4 mo (Table 2). He is now well without recurrence of CD and ALL remains in complete remission over 6-y after completion of chemotherapy. Several cases of CNS leukemia associated with CS have been reported [3–5]. Hyman et al. reported that eight of 59 patients (13.6 %) with CNS leukemia were clinically diagnosed as CS [3]. Leukemic cells usually infiltrate into the meninges, however Danon et al. hypothesized that the destructive infiltration of leukemic cells into the hypothalamus removed a restraining influence on pituitary function with consequent ACTH hypersecretion [4]. Because no leukemic cells were detected, we concluded that the CD was independent of ALL. Although possibly coincidental, this is the first case. Indian J Pediatr (September 2014) 81(9):952–954 DOI 10.1007/s12098-013-1238-x

Midsubtemporal ridge as a predictor of the lateral loop formed by the maxillary nerve and mandibular nerve: a cadaveric morphological study.

BACKGROUND: The lateral loop formed by the maxillary nerve (V2) and the mandibular nerve (V3) consists of a part of the far lateral triangle of the cavernous sinus. Because this triangle becomes a surgical corridor of the preauricular infratemporal fossa approach and a landmark of the extradural approach for the ganglion-type trigeminal schwannomas, identification of the lateral loop has important implications at the early stage of middle cranial base surgery. We realized that a bony ridge usually existed just lateral to the lateral loop. OBJECTIVE: To nominate midsubtemporal ridge (MSR) as the name for this anatomically unnamed bony ridge and to clarify its features. METHODS: Using 35 cadaver heads, we measured the shape of the MSR on both sides and the distance between the MSR and the adjacent structures. RESULTS: The MSR was recognized in 60 of 70 specimens (85.7%). The bony protrusion was 2.9 ± 1.1 mm in height, 6.0 ± 2.1 mm in width, and 9.1 ± 3.2 mm in length. A single peak with anteroposterior length was common in 47 of 60 specimens (78.3%). The MSR was located at the midpoint of the V2 and V3 in 28 specimens (46.7%) and existed 10.7 ± 3.6 mm lateral from the line that bound the foramen rotundum and the foramen ovale. CONCLUSION: We demonstrate morphological characteristics of the MSR. These data on the MSR will assist the surgeon in identifying the lateral loop as a surgical landmark during middle cranial base surgery.