Masahiro Joko

Endoscopic fenestrations for suprasellar arachnoid cysts

OBJECT The endoscopic treatment of a suprasellar arachnoid cyst (SAC) consists mainly of ventriculocystostomy (VC) and ventriculocystocisternostomy (VCC). However, the most appropriate treatment for these cysts has not been fully determined yet. The authors report on the effectiveness of endoscopic VC for SACs communicating with the basal cisterns, which is demonstrated by preoperative CT cisternography. METHODS The authors retrospectively analyzed the surgical results of patients with an SAC treated using endoscopic fenestration. The patient charts were reviewed for demographic data, clinical presentations, surgical therapies, and clinical outcomes. RESULTS Six consecutive patients with SAC were surgically treated using endoscopic fenestration (VC or VCC) between March 2004 and February 2011. The mean age was 18.5 months (range 5 days to 37 months). Five patients were previously untreated, and 1 patient had previously undergone ventriculoperitoneal shunt placement. Five patients underwent preoperative CT cisternography, and communication between the SAC and the basal cisterns was demonstrated in 3 patients, very slight communication in 1, and no communication in 1. Four patients, including the 3 with communication between the SAC and basal cisterns, underwent VC. Two patients with very slight or no communication underwent VCC. In all patients the SAC decreased in size and hydrocephalus improved postoperatively. Five patients (3 treated with VC and 2 with VCC [83%]) have been stable without reoperation (mean follow-up 32.7 months). All 3 patients with an SAC communicating with the basal cisterns have been stable without reoperation following VC. CONCLUSIONS Preoperative cisternography may be useful for selecting the optimal endoscopic treatment method for SAC. If an SAC communicates with the basal cisterns, a VC could be an effective, safe, and simpler treatment option.

A large retro-odontoid cystic mass caused by transverse ligament degeneration with atlantoaxial subluxation leading to granuloma formation and chronic recurrent microbleeding case report

BACKGROUND CONTEXT Noninfectious nontumorous retro-odontoid masses are rare, and masses have not been reported to extensively compress the spinal cord. We encountered a case of a large retro-odontoid lesion that extensively compressed the spinal cord. CASE REPORT A 76-year-old-man reported experiencing a sudden onset of neck pain, hand and foot paresthesia, dysarthria, and dysphagia. When symptoms had not eased by 10 days of treatment with external stabilization and bed rest, he was referred to our hospital. Dynamic radiographs of the cervical spine showed that the atlantodental interval widened from 2 mm on extension to 7 mm on flexion. Computed tomography did not reveal abnormality of the odontoid process or the presence of a high-density area that could suggest calcification in or near the cystic mass. Fluid-attenuated inversion recovery axial magnetic resonance image showed a mass that was 3.0-cm wide, 2.7-cm high, and 2.5-cm thick that severely compressed the lower brain stem. T2-weighted magnetic resonance imaging showed that the mass contained a solid part posterior to the C2 dense area, extending rostrally, compatible with the presence of degenerated and hypertrophic ligaments. We performed surgical decompression of the lesion combined with atlantoaxial fixation. The partly cystic mass, which was located extradurally, had xanthochromic content, indicating microbleeding. Dysarthria and dysphagia immediately disappeared, and neurologic symptoms disappeared by 1 month. At 1-year follow-up, the patient remained symptom free, and computed tomography scans did not show recurrence of the mass. The pathologic diagnosis of degenerative ligament tissue with chronic recurrent microbleeding and associated granulation was made. DISCUSSION A possible explanation why the cyst grew to an exceptionally large size is that the transverse ligament of axis became degenerated and hypertrophic because of chronic mechanical stress by atlantoaxial subluxation. Then, a part of the ligament developed reactive granulation with small vessel formation. Finally, rupture of these small vessels caused repeated episodes of microbleeding, resulting in formation of a large cyst. The observation of degenerative ligament tissue, granulation formation, and microbleeding differentiated it from a synovial cyst or a ganglion cyst. The presence of hemosiderin deposits suggested chronic recurrent microbleeding. Taking all our findings together, we believe that our case of retro-odontoid cystic mass is different from the others that have been reported. Atlantoaxial instability may cause a large mass, such as we described here, so that careful observation is important.

Surgical Intervention for Instability of the Craniovertebral Junction

Surgical approaches for stabilizing the craniovertebral junction (CVJ) are classified as either anterior or posterior approaches. Among the anterior approaches, the established method is anterior odontoid screw fixation. Posterior approaches are classified as either atlanto-axial fixation or occipito-cervical (O-C) fixation. Spinal instrumentation using anchor screws and rods has become a popular method for posterior cervical fixation. Because this method achieves greater stability and higher success rates for fusion without the risk of sublaminar wiring, it has become a substitute for previous methods that used bone grafting and wiring. Several types of anchor screws are available, including C1/2 transarticular, C1 lateral mass, C2 pedicle, and translaminar screws. Appropriate anchor screws should be selected according to characteristics such as technical feasibility, safety, and strength. With these stronger anchor screws, shorter fixation has become possible. The present review discusses the current status of surgical interventions for stabilizing the CVJ.

Pathomorphological description of the shunted portion of a filum terminale arteriovenous fistula

BACKGROUND CONTEXT The clinical morphology of a filum terminale arteriovenous fistula (f-AVF) is well known; however, pathological details of the fistulized portion are unknown. Herein, we report the pathological findings of the f-AVF. STUDY DESIGN Case report and literature review. PURPOSE To present a detailed pathological examination of the fistulized portion of the f-AVF. METHODS A 71-year-old man presented with gradually worsening bilateral foot paresthesias and anal dysesthesia. T2-weighted magnetic resonance imaging showed flow voids surrounding an edematous conus medullaris and cauda equina with spinal stenosis at L3-L4 and L4-L5. Spinal digital subtraction angiography demonstrated an f-AVF fed by the left T9 intercostal artery. RESULTS We performed laminotomies of L3 and L4 to open the dura mater and found a hypertrophic filum terminale. It was resected, leaving a length of 2 cm between the abnormal proximal end and normal distal end. The f-AVF completely disappeared after the surgery. On pathological examination, the filum terminale included two vessels at the proximal end and one at the distal end. At the proximal end, immunostaining showed one vessel that was definitively an artery with both an internal elastic membrane (IEM) and smooth muscle. The other was a vein and lacked an IEM. On the distal side, the collagen fibers gradually increased, the IEM partially disappeared from the arterial wall, and the vein became arterialized with a thin IEM. At the distal end the two vessels joined. Therefore, we speculated that the fistulized portion of the f-AVF was not a fistula point but had some lengths where the artery had characteristics of a vein and there was venous arterialization. CONCLUSIONS The filum arteriovenous shunting occurred at the portion where there was venous arterialization and the artery had the characteristics of a vein. Therefore, resecting the filum terminale requires more proximal from the normal distal end.

Radiographic measurements of C-2 in patients with atlas assimilation.

OBJECT The object of this study was to evaluate the radiographic characteristics of C-2 using multiplanar CT measurements for anchor screw placement in patients with C-1 assimilation (C1A). Insertion of a C-2 pedicle screw in the setting of C1A is relatively difficult and technically demanding, and there has been no report about the optimal sizes of the pedicles and laminae of C-2 for screw placement in C1A. METHODS An institutional database was searched for all patients who had undergone cervical CT scanning and cervical spine surgery between April 2006 and December 2012. Two neurosurgeons reviewed the CT scans from 462 patients who met these criteria, looking for C1A and other anomalies of the craniocervical junction such as high-riding vertebral artery (VA), basilar invagination, and VA anomaly. The routine axial images were reloaded on a workstation, and reconstruction CT images were used to measure parameters: the minimum width of bilateral pedicles and laminae and the length of bilateral laminae of the atlas. RESULTS Seven patients with C1A were identified, and 14 sex-matched patients without C1A were randomly selected from the same database as a control group. The mean minimum pedicle width was 5.21 mm in patients with C1A and 7.17 mm in those without. The mean minimum laminae width was 5.29 mm in patients with C1A and 6.53 mm in controls. The mean minimum pedicle and laminae widths were statistically significantly smaller in the patients with C1A (p < 0.05). CONCLUSIONS In patients with C1A, the C-2 bony structures are significantly smaller than normal, making C-2 pedicle screw or translaminar screw placement more difficult.

Different modifications of phosphorylated Smad3C and Smad3L through TGF-β after spinal cord injury in mice

Transforming growth factor-β (TGF-β) is an anti-inflammatory cytokine and is expressed in the injured spinal cord. TGF-β signals through receptors to activate Smad proteins, which translocate into the nucleus. In the present study, we investigated the chronological alterations and cellular locations of the TGF-β/Smad signaling pathway following spinal cord injury (SCI) in mice. ELISA analysis showed that the concentration of interleukin-6 (IL-6) in injured spinal cords significantly increases immediately after SCI, while the concentration of TGF-β gradually increased after SCI, peaked at 2 days, and then gradually decreased. Immunohistochemical studies revealed that Smad3 was mainly expressed in neurons of the spinal cord. Phosphorylated Smad3 at the C-terminus (p-Smad3C) was stained within the motor neurons in the anterior horn, while phosphorylated Smad3 at the linker regions (p-Smad3L) was expressed in astrocytes within gray matter. These findings suggest that SCI induces gradual increases in TGF-β and induces different activation of p-Smad3C and p-Smad3L. Phosphorylated Smad3C might be involved in neuronal degeneration after SCI, and p-Smad3L may play a role in glial scar formation by astrocytes.