Chenlong Liao

Surgical Decompression of Painful Diabetic Peripheral Neuropathy: The Role of Pain Distribution

Objective To investigate the effect of surgical decompression on painful diabetic peripheral neuropathy (DPN) patients and discuss the role which pain distribution and characterization play in the management of painful DPN as well as the underlying mechanism involved. Methods A total of 306 patients with painful diabetic lower-extremity neuropathy were treated with Dellon surgical nerve decompression in our department. Clinical evaluation including Visual analogue scale (VAS), Brief Pain Inventory Short Form for diabetic peripheral neuropathy (BPI-DPN) questionnaire, two-point discrimination (2-PD), nerve conduction velocity (NCV) and high-resolution ultrasonography (cross-sectional area, CSA) were performed in all cases preoperatively, and at 6 month intervals for 2 years post-decompression. The patients who underwent surgery were retrospectively assigned into two subgroups (focal and diffuse pain) according to the distribution of the diabetic neuropathic pain. The control group included 92 painful DPN patients without surgery. Results The levels of VAS, scores in BPI-DPN, 2-PD, NCV results and CSA were all improved in surgical group when compared to the control group (P<0.05). More improvement of VAS, scores in BPI-DPN and CSA was observed in focal pain group than that in diffuse group (P<0.05). Conclusions Efficacy of decompression of multiple lower-extremity peripheral nerves in patients with painful diabetic neuropathy was confirmed in this study. While both focal and diffuse group could benefit from surgical decompression, pain relief and morphological restoration could be better achieved in focal group.

Symptomatic Trigeminal Neuralgia Caused by Cerebellopontine Angle Tumors.

To investigate the characteristics of symptomatic trigeminal neuralgia (TN) caused by tumors and the relationship between anatomicosurgical findings and tumor type, the authors undertook a retrospective review of 35 patients with symptomatic TN between 2006 and 2015. The tumors included 16 meningiomas, 14 epidermoids, 4 vestibular schwannomas, and 1 hemangioblastoma. The studies show that patients with tumor-induced TN were significantly younger than those idiopathic TN (P <0.05). Meningioma-induced TN tended to have responsible vessels, while epidermoid tumor seemed to cause TN by wrapping or compressing the nerve. Additional vascular compression was observed in 15 (42.9%) of these 35 patients. All patients except one showed immediate pain relief following total or subtotal tumor removal with microvascular decompression (if required). Two patients with epidermoid-induced TN experienced symptom relapses caused by tumor regrowth, and one with meningioma-induced TN experienced pain recurrence caused by adhesive arachnoid. The key for operative success is to examine the entire nerve root for possible vascular compression after total or subtotal tumor resection.Abstract To investigate the characteristics of symptomatic trigeminal neuralgia (TN) caused by tumors and the relationship between anatomicosurgical findings and tumor type, the authors undertook a retrospective review of 35 patients with symptomatic TN between 2006 and 2015. The tumors included 16 meningiomas, 14 epidermoids, 4 vestibular schwannomas, and 1 hemangioblastoma. The studies show that patients with tumor-induced TN were significantly younger than those idiopathic TN (P <0.05). Meningioma-induced TN tended to have responsible vessels, while epidermoid tumor seemed to cause TN by wrapping or compressing the nerve. Additional vascular compression was observed in 15 (42.9%) of these 35 patients. All patients except one showed immediate pain relief following total or subtotal tumor removal with microvascular decompression (if required). Two patients with epidermoid-induced TN experienced symptom relapses caused by tumor regrowth, and one with meningioma-induced TN experienced pain recurrence caused by adhesive arachnoid. The key for operative success is to examine the entire nerve root for possible vascular compression after total or subtotal tumor resection.

Improved neural microcirculation and regeneration after peripheral nerve decompression in DPN rats

Abstract Objective: Recently, neural microcirculation and regeneration were regarded as critical factors in diabetic peripheral neuropathy (DPN) improvement. In the present study, we explored the cytological and molecular mechanisms how peripheral nerve decompression impaired nerve injury. Methods: Forty-five male SD rats were established as the DPN model. HE staining was used to observe the morphology and distribution of microvessels. Transmission electron microscopy was applied to observe the morphology and distribution of Schwann cells. Immunohistochemical staining was performed to measure nerve growth factor (NGF), tyrosine kinase receptor A (TrkA) and growth-associated protein 43 (GAP-43) in the distal sciatic nerve. Results: Distribution of microvessels and Schwann cells decreased in the DPN group (p < 0.05). NGF, TrkA and GAP-43 also decreased significantly in the DPN group (p < 0.05). NGF, TrkA, GAP-43 and distribution of microvessels and Schwann cells increased in the decompressed group (p < 0.05). Discussion: In DPN rats, after nerves are compressed, microcirculation disturbance and hypoxia ischemia will happen, which cause decreased expression of NGF, TrkA and GAP-43. Finally, the self-healing function of compressed nerves is impacted. Conversely, nerve decompression can improve neural microcirculation and regeneration and change the former pathological process.

Endoscopic Endonasal Approach for Craniovertebral Junction Pathologic Conditions: Myth and Truth in Clinical Series and Personal Experience

OBJECTIVE For many years, the microsurgical transoral approach has been accepted as the gold standard for anterior decompressions of the craniovertebral junction (CVJ). The introduction of the endoscopic endonasal approach (EEA) has gained wide recognition and overwhelming support in recent years, including for diseases of the CVJ. The aim of this study was to critically analyze and discuss all cases of CVJ diseases approached by means of an EEA so far reported in the literature, including our institutional experience consisting of 6 consecutive patients. METHODS Six consecutive patients affected by CVJ disease underwent an EEA. Three patients had a tumor (2 chordomas and 1 myeloma) and 3 had impressio basilaris. RESULTS Five patients had an uncomplicated postoperative course and 1 developed an intraoperative cerebrospinal fluid leak and subsequent meningitis and died 5 weeks after surgery. A total of 107 patients (including our 6) affected by CVJ disease and treated with EEA have been reported so far. Among these patients, cerebrospinal fluid leak was reported in 13 (12.4%), transient velopharyngeal incompetence in 6 (5.6%), postoperative epistaxis in 2 (1.86%), and respiratory dysfunction requiring a tracheostomy in 2 (1.86%). In our extended institutional series of more than 20 consecutive anterior decompressions for CVJ diseases (including transoral and transnasal microsurgical approaches), the only fatal complication was associated with EEA. CONCLUSIONS On the basis of the reviewed literature and our personal experience, the reported increased safety of the EEA needs to be reassessed and discussed.

Association of myelinated primary afferents impairment with mechanical allodynia in diabetic peripheral neuropathy: an experimental study in rats

To investigate the mechanisms underlying the efficacy of surgical treatment for painful diabetic peripheral neuropathy. Rats were initially divided into 3 groups (I, control rats, II, streptozotocin-induced diabetic rats, III, streptozotocin-induced diabetic rats with latex tube encircling the sciatic nerve without compression). When mechanical allodynia (MA) became stable in the third week, one third of group III rats were sacrificed and the remainder were further divided into subgroups depending on whether the latex tube was removed. Except for some rats in group III, all rats were sacrificed in the fifth week. Morphometric analysis of nerve fibers was performed. Expression level of GABAB receptor protein in spinal dorsal horn was determined. Changes of GABAB receptor within areas of primary afferents central terminal were identified. Chronic nerve compression caused by the interaction of diabetic nerves swelling and the encircling latex tube increased the incidence of MA in diabetic rats, and nerve decompression could ameliorate MA. In diabetic rats with MA, demyelination of myelinated fibers was noted and reduction of GABAB receptor was mainly detected in the area of myelinated afferent central terminals. MA in DPN should be partially attributed to compression impairment of myelinated afferents, supporting the rationale for surgical decompression.To investigate the mechanisms underlying the efficacy of surgical treatment for painful diabetic peripheral neuropathy. Rats were initially divided into 3 groups (I, control rats, II, streptozotocin-induced diabetic rats, III, streptozotocin-induced diabetic rats with latex tube encircling the sciatic nerve without compression). When mechanical allodynia (MA) became stable in the third week, one third of group III rats were sacrificed and the remainder were further divided into subgroups depending on whether the latex tube was removed. Except for some rats in group III, all rats were sacrificed in the fifth week. Morphometric analysis of nerve fibers was performed. Expression level of GABAB receptor protein in spinal dorsal horn was determined. Changes of GABAB receptor within areas of primary afferents central terminal were identified. Chronic nerve compression caused by the interaction of diabetic nerves swelling and the encircling latex tube increased the incidence of MA in diabetic rats, and nerve decompression could ameliorate MA. In diabetic rats with MA, demyelination of myelinated fibers was noted and reduction of GABAB receptor was mainly detected in the area of myelinated afferent central terminals. MA in DPN should be partially attributed to compression impairment of myelinated afferents, supporting the rationale for surgical decompression.

Microvascular Decompression for Trigeminal Neuralgia: The Role of Mechanical Allodynia

OBJECTIVE This study was conducted to determine whether mechanical allodynia (MA) acts as a predictor of outcome after microvascular decompression (MVD) for trigeminal neuralgia (TN) and to discuss the potential pathologic mechanisms involved. METHODS A series of 246 patients who underwent MVD for TN were involved in the study. The classifications were based on the characteristic of pain (shocklike or constant), and the presence of MA was defined from the chart review, retrospectively. Surgical outcomes are defined as excellent, good, or poor. Immediate and long-term outcomes were compared to provide the information on recurrence and delayed relief. The relationship among the groups was investigated, and the strength was determined. RESULTS The presence of MA and the type of TN pain are significant predictors of surgical outcome (P < 0.05). MA was proved to be an independent predictor of surgical outcome and a significant predictor of existence of neurovascular compression (P < 0.05) and lower rate of recurrence (P < 0.05). No statistically significant predictors of delayed relief were detected in this study. CONCLUSIONS The presence of MA is a reliable predictor of immediate and long-term outcome after MVD for TN. Compared with the patients without MA, the incidence rate of intraoperative neurovascular compression was higher in MA-positive patients, who were more likely to achieve a better outcome and lower rate of recurrence after MVD for TN. Application of the information in this study will be helpful in patient selection of MVD for TN.

Facial-Hypoglossal End-To-Side Neurorrhaphy: Exploration of the Source of Axonal Sprouting

Background The clinical application of end-to-side (ETS) neurorrhaphy is under debate partly due to a lack of consensus on the source of axonal sprouting. Methods In this study, 24 rats were divided into three groups: sham operation, facial-hypoglossal ETS neurorrhaphy, and end-to-end (ETE) neurorrhaphy. Electrophysiological tests were employed to detect the evoked compound muscle action potentials (CMAPs) in different situations, and the latencies and maximal amplitudes of the CMAPs recorded were compared. Fluorescence retrograde tracing studies, hematoxylin and eosin (HE) staining, and immunohistochemical staining of growth-associated protein 43 (GAP-43) were performed. The number and the diameter of myelinated axons proximal and distal to the coaptation sites were measured. Results Twelve weeks after the surgeries, reinnervation of whisker pad muscles by hypoglossal nerves in both the ETS and ETE groups were confirmed via electrophysiological study. The maximal amplitudes of the CMAPs recorded in different situations and the quantification of myelinated axons supported the coexistence spontaneous collateral sprouting and regenerative sprouting of axons. Double-labeled neurons were found within the hypoglossal nuclear areas in the ETS neurorrhaphy group and HE staining illustrated the axons crossed the coaptation site into the facial acceptor nerve. Although immunohistochemical staining of GAP-43 revealed different timeframes between ETS and ETE neurorrhaphy groups, no significant difference on latency or diameters of the myelinated axons distal to the coaptation sites was noted between ETE and ETS groups. Conclusion Both spontaneous collateral sprouting and regenerative sprouting of axons coexisted following ETS neurorrhaphy, which represents an alternative approach to peripheral nerve reconstruction.

The Role of Percutaneous Radiofrequency Thermocoagulation for Persistent or Recurrent Trigeminal Neuralgia After Surgery.

AbstractTherapeutic strategy is controversial and not yet uniform for patients with trigeminal neuralgia (TN) and persistent or recurrent facial pain after microvascular decompression, percutaneous radiofrequency thermocoagulation (PRT), or Gamma Knife surgery. The outcomes and risks of PRT for these patients are not clearly understood. The authors performed a retrospective study of 84 patients with persistent or recurrent TN after surgery who then underwent PRT between 2007 and 2013. Data were obtained with chart review and telephone interviews. The mean follow-up duration was 44.2 months. The immediate pain relief after PRT was 98%. The survival rates of pain free without medications at 1, 2, and 3 years after PRT were 85%, 68%, and 54%, respectively, with a nearly 80% rate for effective pain control (pain free, or pain controlled with medications) during the study period. The previous surgical method for TN did not have a significant effect on pain-free rates (P >0.05). Ninety-five percent of patients benefited from multiple PRT procedures and were satisfied with their pain relief. Fourteen of 17 patients who required retreatment selected additional PRT, resulting in 8 patients (57%) in excellent outcome and 12 (86%) in effective pain control. Two patients had failed all conventional invasive treatments. All patients experienced numbness of varying degrees, with 2 reporting severe and bothersome numbness. The complication rate was 15%, including 6 patients with masseter weakness, 2 patients with impaired taste acuity, 4 patients with absent or decreased corneal reflex, 1 patient with oculomotor paralysis. Percutaneous radiofrequency thermocoagulation is a safe and efficacious therapeutic method for patients with persistent or recurrent TN after surgery. Percutaneous radiofrequency thermocoagulation can serve as an alternative treatment option for these patients.

Narrow Foramen Ovale and Rotundum: A Role in the Etiology of Trigeminal Neuralgia.

AbstractPrimary trigeminal neuralgia (TN) may occasionally occur in absence of neurovascular compression. A mechanism other than nerovascular compression may play a role in TN. High-resolution computed tomographies (CTs) of 21 consecutive TN patients without vascular compression during surgery and 30 healthy volunteers were retrospectively performed. Measuring parameters (length, width, and aspect ratio) were obtained in the axial plane for foramen ovale, and in the reconstructed coronal plane for foramen rotundum on both sides in each subject. The right-sided foramen ovale is slightly narrower than the left-sided, but no difference was observed between the sides. No correlation was found between the foramen size and the gender in both groups. The affected side with a narrower ovale foramen (>0.5 mm) and a significantly greater aspect ratio compared with the unaffected side may contribute to TN. Meanwhile, no significant correlation, but more likely a tendency, was found between the right and left sides in size of foramen rotundum (P = 0.09). This study has speculatively suggested that a narrow skull foramen may be etiologically important in a small percentage of TN patients. If recurrent or residual TN was encountered in cases of TN without vascular compression during surgery, high-resolution CT may help to evaluate the anatomical morphology of skull foramen in great detail.

Comparison of 4 Different Methods for Direct Hypoglossal-Facial Nerve Anastomosis in Rats

BACKGROUND Classic hypoglossal-facial nerve anastomosis inevitably causes hemitongue atrophy and dysfunction. Thus, many variants have been developed to reduce tongue-related morbidities. A comparative study concerning these techniques was conducted in rats to systematically evaluate long-term functional and histologic outcomes of the recipient and donor systems. METHODS Rats (8 per group) were treated by end-to-end neurorrhaphy (EEN), EEN using the hemisectioned and longitudinally split donor nerve (EEN-Hemi), end-to-side neurorrhaphy through a perineurial window (ESN-PW), or 30% to 40% partial neurotomy (ESN-PN). Four additional rats were left intact. At 8 months postoperatively, behavioral, electrophysiologic, and morphologic studies were carried out to compare the groups. RESULTS All techniques resulted in partial functional recovery, but complete restoration was not obtained. There were no significant differences between the experimental groups in axon diameter or myelin thickness. The facial nerve fiber count after ESN-PN, but not after EEN-Hemi or ESN-PW, was comparable with that after EEN, which agreed with the behavioral and electrophysiologic results. The hypoglossal nerve fiber count after ESN-PN was slightly less than that after ESN-PW, but markedly more than that after EEN-Hemi, corresponding to the electrophysiologic examination. Quantitative measures of muscle fiber cross-sectional area and connective tissue area density of the tongue demonstrated severe muscle atrophy on the operated side after EEN and EEN-Hemi when compared with ESN-PW and ESN-PN. CONCLUSIONS ESN with 30% to 40% partial donor neurotomy offers the best balance between motor reinnervation and donor deficits. The method of nerve split for provision of hemihypoglossal nerve stump may not effectively preserve the tongue function.