One-screw fixation provides similar stability to that of two-screw fixation for type II dens fractures.

BACKGROUND: Anterior screw fixation has been widely adopted for the treatment of type II dens fractures. However, there is still controversy regarding whether one- or two-screw fixation is more appropriate. QUESTIONS/PURPOSES: We addressed three questions: (1) Do one- and two-screw fixation techniques differ regarding shear stiffness and rotational stiffness? (2) Can shear stiffness and rotational stiffness after screw fixation be restored to normal? (3) Does stiffness after screw fixation correlate with bone mineral density (BMD)? METHODS: We randomly assigned 14 fresh axes into two groups (seven axes each): one receiving one-screw fixation and another receiving two-screw fixation. Shear and torsional stiffness were measured using a nondestructive low-load test in six directions. A transverse osteotomy then was created at the base of the dens and fixed using one or two screws. Shear and torsional stiffness were tested again under the same testing conditions. RESULTS: Mean stiffness in all directions after screw fixation was similar in both groups. The stiffness after one- and two-screw fixation was not restored to normal: the mean shear stiffness restored ratio was less than 50% and the mean torsional stiffness restored ratio was less than 6% in both groups. BMD did not correlate with mean stiffness after screw fixation in both groups. CONCLUSIONS: One- and two-screw fixation for type II dens fractures provide similar stability but neither restores normal shear or torsional stiffness. CLINICAL RELEVANCE: One-screw fixation might be used as an alternative to two-screw fixation. Assumed BMD should not influence surgical decision making.

Peripheral nerve stimulation: lead position monitoring by reconstruction CT angiography--a technical report.

BACKGROUND: The authors investigated the possibility of improving positioning of stimulation leads in patients with chronic neuropathic peripheral nerve pain and good pain relief from implantation of a peripheral nerve stimulator (PNS). METHODS: This pilot study includes four patients suffering from Chronic Regional Pain Syndrome type II (CRPS II) or neuropathic mononeuropathy treated with PNS therapy. The affected extremities and corresponding implantation sites were examined using computer tomographic scans (CT), additional CT angiography (CTA), reconstruction techniques and postprocessing procedures. RESULTS: It was possible to prove a close relation between the implanted device and the neurovascular bundle in each of these cases. Thus, indirect lead position control was obtained. CONCLUSIONS: Computer tomographic techniques represent a reliable method for the position control of implanted peripheral nerve electrodes. Hence, this procedure should surpass general radiographies in detecting lead displacements.

Operative and technical complications of vagus nerve stimulator implantation.

BACKGROUND: The treatment of refractory epilepsy by vagus nerve stimulation (VNS) is a well-established therapy option for patients not suitable for epilepsy surgery and therapy refractory depressions. OBJECTIVE: To analyze surgical and technical complications after implantation of left-sided VNS in patients with therapy-refractory epilepsy and depression. METHODS: One hundred five patients receiving a VNS or VNS-related operations (n = 118) from 1999 to 2008 were investigated retrospectively. RESULTS: At the time of operation, 84 patients were younger than 18 years, with a mean age of 10.5 years. Twenty (19%) patients had technical problems or complications. In 6 (5.7%) patients these problems were caused by the operation. The device was removed in 8 cases. The range of surgically and technically induced complications included electrode fractures, early and late onset of deep wound infections, transient vocal cord palsy, cardiac arrhythmia under test stimulation, electrode malfunction, and posttraumatic dysfunction of the stimulator. CONCLUSION: VNS therapy is combined with a wide spread of possible complications. Technical problems are to be expected, including electrode fracture, dislocation, and generator malfunction. The major complication in younger patients is the electrode fracture, which might be induced by growth during adolescence. Surgically induced complications of VNS implantation are comparably low. Cardiac symptoms and recurrent nerve palsy need to be taken into consideration.

Right-sided vagus nerve stimulation in humans: an effective therapy?

Vagus nerve stimulation (VNS) is an additive treatment option for refractory epilepsy. The electrode is placed on the cervical trunk of the left vagus nerve. In patients who are not suitable for left-sided vagus nerve stimulation (L-VNS) right-sided vagus nerve stimulation (R-VNS) may be as effective. In animal models epilepsy is sufficiently suppressed by R-VNS. In a 16 years old boy suffering from medically refractory psychomotoric seizures with secondary generalisation, L-VNS reduced the frequency of generalized seizures. A deep wound infection required the removal of the system eight weeks later. Cicatrisation did not allow preparation of the left vagus nerve, therefore we implanted R-VNS with sufficient seizure suppression. However, compared to L-VNS, the effect occurred months later and cardiac symptoms were induced by stimulation of the right vagus nerve. R-VNS seems to be an effective and alternative therapy in selected patients responding to L-VNS where a left-sided reimplantation is not possible. Placement and adjustment of the device should be performed under ECG control. Further studies are necessary to compare the efficacy of L-VNS and R-VNS.

Case reports: a rare cause of radicular complaints: ligamentum flavum hematoma.

Hematomas in the lumbar ligamentum flavum are rare and may generate signs and symptoms of lumbar nerve root compression or neurogenic claudication similar to the far more common degenerative diseases. The pathogenesis of these hematomas is unclear. Ruptured irregular vessels of the degenerated and hypertrophic ligamentum flavum were assumed. We diagnosed three patients with a flavum hematoma intraoperatively leading to radicular complaints and spinal claudication. One occurred as a complication of local infiltration therapy, and the other two patients reported minor trauma as the releasing factor. Using spinal magnetic resonance imaging, a preoperative diagnosis is possible but the differentiation to synovial cysts is difficult. Surgical resection of the ligamentum flavum, including the hematoma, provided adequate treatment in these patients.