[The ineffective or short-term recurrence of trigeminal neuralgia after microballoon compression:different causes and management strategies]

Objectives: To explore the causes of ineffective or short-term recurrence (within 3 months)of trigeminal neuralgia treated by percutaneous microballoon compression(PBC), and to examine the reoperative strategies and clincal outcomes of modified PBC. Methods: The clinical data of 21 patients with ineffective or short-term recurrence after PBC treatment (5.7% of 369 patient received PBC) admitted to the Department of Neurosurgery,Nanjing Drum Tower Hospital Clinical College of Nanjing Medical University from June 2018 to June 2020 were retrospectively analyzed.There were 8 males and 13 females, mean aged 66.6 years (range:51 to 79 years).Among them,2 patients was ineffective after PBC and 19 patients relapsed within 3 months.The distribution of pain was along V₂ branches in 2 cases,V₃ branches in 3 cases,V₁+V₂ branches in 1 case,and V₂+V₃ branches in 15 cases.The mean time of recurrence was 46.8 days (range:23 to 76 days) among the 19 patients with short-term recurrence.The patients were divided into 4 types based on the causes of postoperative ineffectiveness or short-term recurrence.TypeⅠ:extracapsular false pear (1 case);Type Ⅱ:invalid true pear(2 cases);Type Ⅲ:capsular rupture (6 cases);Type Ⅳ:compression blind area (12 cases).The individualized modified PBC operation plans were used according to the types of the patients and the clinical effect and complications of the patients were observed. Results: The pain symptoms of the patients disappeared after the second operation with immediate effective rate of 100%. All patients had mild facial numbness after surgery.Five patients(23.8%,5/21) had masseter muscle weakness, 3 (14.3%,3/21) had peristomatous herpes, 1(4.8%, 1/21) had diplopia.No bleeding or other complications occurred.All patients were followed up for at least 12 months (range:13 to 28 months). One patient (4.8%,1/21) (compression blind area type) had pain recurrence 9 months after surgery, and cured by receiving the original modified PBC surgery again with no recurrence after another 13 months' follow-up. None of the other patients relapsed during the follow-up period.Up to the last follow-up,19 cases(90.5%,19/21) were cured,and 2 cases (9.5%,2/21) were relieved. Conclusions: The main reason for ineffective or short-term recurrence of PBC in trigeminal neuralgia patients is the ineffectively compressed of trigeminal ganglion.According to the different types of patients,the use of individualized modified surgical scheme can improve the efficacy of PBC surgery.

The conductive properties of single DNA molecules studied by torsion tunneling atomic force microscopy

The conductive properties of single natural λ-DNA molecules are studied by torsion tunneling atomic force microscopy (TR-TUNA). The currents both parallel to and perpendicular to the DNA chains are investigated, but only weak or even no current signals are detected by TR-TUNA. To improve the conductance of DNA molecules, silver and copper metallized DNAs are fabricated and their conductivities are checked by TR-TUNA. It is found that for both Cu- and Ag-DNAs, the conductivity perpendicular to the DNA chain is enhanced significantly as the metal clusters are attached to the DNA chains. But parallel to the chain the electrical transport is still weak, most probably due to the 'beads-on-a-string' constructions of metallized DNAs.