Exploration of an Easy and Simple Method for Decompressive Craniectomy: The "Spiral Dural Incision Method".

Decompressive craniectomy (DC) is performed to alleviate intracranial hypertension as much as possible. There are two additional goals that surgeons should strive to achieve: minimization of operating time (i.e., the time issue) and avoidance of manually pushing on the surface of the bulging brain to prevent iatrogenic brain injury (i.e., "stuffing risk"). Many authors have made progress on the time issue, but stuffing risk remains largely unmitigated. We recently presented a new DC method that resolved both issues, but the incision design was too complicated for general use. A recent study has presented a duraplasty method that does not use watertight sutures and does not exacerbate the risk associated with DC. Employing the simplified method without sutures, we developed a new, easy-to-perform DC method that resolves stuffing risk. We analyzed the incision design geometrically and verified it by simulations generated with a physics engine. Three patients with massive cerebral infarction, subarachnoid hemorrhage, and hemorrhagic infarction underwent the new procedure. The targeted incision design was composed of four or five curved incision lines. Expansion of the dura resulted in transformation into a centroclinal form with spiral rifts and canopy. The dura expanded as expected in each case, and no cases required manual stuffing of the bulging brain. The operative time was acceptable, and no complications were reported. The concept of the incision design could be applied to any polygonal duraplasty in DC. We developed a new DC method that involves a simple and easily executed incision design, avoided stuffing risk.

Design of a Locator for Designing the Shortest Incision for a Polygonal Dural Window.

When a wide polygonal dural window is created, a short dural incision length is preferred by surgeons because suturing a wastefully long incision line during closure is troublesome. A locator to facilitate making the shortest dural incision when creating a polygonal dural window would be helpful. We geometrically analyzed the shortest incision design for a pentagonal dural window and produced a simple locator for intraoperatively implementing this design. The design for a pentagonal dural window with the shortest incision is the same as the design for a minimum Steiner tree (MST) problem with five vertices. The MST consists of three interconnected Steiner points (SPs) with three equal, radiating branches. We produced a template of the features of the MST for a polygon (MST template) as a locator. The MST template consists of several uniform Steiner units (SUs), each of which has an SP at the center and three wings that branch off of the SP, and each SU also has three slits through which the wings of another unit can pass. This mechanism allows us to freely adjust the distance between the SPs of separate SUs. In clinical practice, we can create the shortest incision design for a quadrilateral or pentagon by arranging MST templates combining two or three SUs. If we open a wide dural window, the total incision lengths created using our method are 1-5 cm shorter than conventional incisions. The MST template accurately and easily reveals the shortest incision design.

[Shunt passer clamp: a new device to prevent rotation of CSF-shunt passer].

Cerebrospinal fluid shunting is a surgical treatment alternative for hydrocephalus. In general, ventriculoperitoneal (VP) and lumboperitoneal (LP) shunts have been widely practiced as standard procedures. However, these procedures are difficult because the shunt passer often rotates unintentionally. Therefore, we developed a simple device that prevents shunt passer rotation and termed it a "shunt passer-clamp"(SP-C). This device consists of two parts: the first part is the body with a hole through which the passer goes and a "female" screw perpendicular to the hole. The second part is a "male" screw set to the body. The surgeon can attach the SP-C to the shunt passer without the requirement for remodeling. We employed a SP-C for 14 consecutive shunt surgeries and received favorable feedback from the surgeons. Handling was considered "easy" in all cases. The surgical duration was significantly shorter than that if the SP-C was not employed. We conclude that our specially designed SP-C is relatively effective.

[Analysis of initial treatment only by linac-based stereotactic radiosurgery for a metastatic brain tumor from non-small cell lung cancer].

A patient who receives stereotactic radiosurgery(SRS)alone for treating the brain metastatic lesion has a risk of tumor recurrence in the brain. Thus, some patients undergo prophylactic whole brain radiotherapy(WBRT)in addition to the SRS. However, the usefulness of adding WBRT is still debatable. In our hospitals, we initially treat metastatic brain tumors with SRS alone, and have experienced 2 long-surviving cases. Here, we report our treatment outcomes, including those for these 2 cases, and discuss the treatment plan for non-small cell lung cancer(NSCLC)with brain metastases. Forty-two brain metastatic cases were studied. Median survival(MS), tumor control rate(TCR), and recurrence ratio at distant site(RRDS)in the brain were analyzed. Age, Karnofsky performance status(KPS), and recursive partitioning analysis(RPA)class were analyzed as prognostic factors. We present 2 cases of a 42- and a 56-year-old man, surviving for more than 100 months. MS, TCR, and RRDS at 1 year in our hospitals were 20 months, 89.1%, and 25.6%, respectively. The prognostic factors were good KPS and RPA class and younger age. Our data showed a good MS among some reliable random controlled trials. Our strategy of SRS alone preserves the possibility to treat new lesions with WBRT. Prognosis was mainly defined by the systemic condition of the patient and activity of the primary lesion. Thorough treatment of the primary lesion with addition of SRS for initial treatment of metastatic lesions and scheduled MRI follow-up will provide for longer survival times.

Intracerebral foreign body granuloma caused by a resorbable plate with passive intraosseous translocation after cranioplasty.

Numerous reports have demonstrated the usefulness of bioresorbable materials, but few have described severe complications caused by delayed degradation. The authors present the case of an intracranial foreign body granuloma caused by plates made of unsintered hydroxyapatite (uHA) particles and poly-l-lactide (PLLA; Super Fixsorb MX, Takiron) after cranioplasty. This 1-month-old boy presented to the authors' department with Pfeiffer syndrome. He had multiple-suture synostosis causing turribrachycephaly, Chiari malformation Type 1, and obstructive sleep apnea syndrome. At 6 months old, the child was treated with multidirectional cranial distraction osteogenesis. The uHA-PLLA plates were applied as base stones to reinforce the pins. After 16 days of distraction and 3 weeks of consolidation, the pins were removed. Seventeen months postoperatively, the plate on the right temporal bone showed passive intraosseous translocation (PIT), and by 2 years postoperatively, the plate was completely left behind in the cerebrum. At 3.5 years postoperatively, MRI disclosed a contrast-enhanced mass with surrounding brain edema at the site of the plate. The lesion was resected. The clinical history and histological specimens led to a diagnosis of foreign body granuloma surrounding the nonabsorbed resorbable plate in the dura mater. Resorbable plates are clearly useful resources in cases in which delayed absorption will not prove problematic, but careful application and follow-up is required when dealing with the growing skull given the possibility of intracranial displacement after PIT.