Simple Microsurgical Extirpation as a Method of Choice in Treating Symptomatic Spinal Facet Joint Cysts: A Retrospective Case Series.

BACKGROUND: Facet joint cysts (FJCs) are a cause of radiculopathy, back pain, cauda equina syndrome, and/or claudication. They mostly affect the lumbar spine in the elderly, prevailing in women, and are connected to spinal degeneration and instability. We aimed to evaluate the safety and efficacy of open surgical decompression and cyst excision without a subsequent fusion. METHODS: We evaluated neurologic symptoms and potential signs of spinal instability on preoperative versus postoperative radiological examination. We performed a histological assessment of the extirpated cysts. Statistical analysis was then performed. RESULTS: Of a total of 66 patients, 44 were included in the present study. The average age was 61.2 years. Female patients prevailed (61.4%). The mean follow-up was 5.3 years. The segment most frequently affected by a FJC was L4-L5 (65.9%). Cyst resection led to significant relief from neurologic symptoms for most patients. Thus, 95.5% of our patients reported their postoperative outcome as excellent. Preoperatively, 43.2% and 47.4% of patients had had radiographic signs of instability on magnetic resonance imaging and signs of spondylolisthesis on dynamic radiographs in the operated segment, respectively, with 54.5% manifesting signs of spondylolisthesis in the same segment on a postoperative dynamic radiograph. Despite spondylolisthesis progression, no patient required reoperation. Histologically, pseudocysts without synovium were more frequent than were synovial cysts. CONCLUSIONS: Simple FJC extirpation is a safe and effective method for resolving radicular symptoms, with excellent long-term outcomes. It does not lead to the development of clinically significant spondylolisthesis in the operated segment; thus, no supplementary fusion with instrumented stabilization is required.

Current trends and outcomes of non-elective neurosurgical care in Central Europe during the second year of the COVID-19 pandemic.

Reflecting the first wave COVID-19 pandemic in Central Europe (i.e. March 16th-April 15th, 2020) the neurosurgical community witnessed a general diminution in the incidence of emergency neurosurgical cases, which was impelled by a reduced number of traumatic brain injuries (TBI), spine conditions, and chronic subdural hematomas (CSDH). This appeared to be associated with restrictions imposed on mobility within countries but also to possible delayed patient introduction and interdisciplinary medical counseling. In response to one year of COVID-19 experience, also mapping the third wave of COVID-19 in 2021 (i.e. March 16 to April 15, 2021), we aimed to reevaluate the current prevalence and outcomes for emergency non-elective neurosurgical cases in COVID-19-negative patients across Austria and the Czech Republic. The primary analysis was focused on incidence and 30-day mortality in emergency neurosurgical cases compared to four preceding years (2017-2020). A total of 5077 neurosurgical emergency cases were reviewed. The year 2021 compared to the years 2017-2019 was not significantly related to any increased odds of 30 day mortality in Austria or in the Czech Republic. Recently, there was a significant propensity toward increased incidence rates of emergency non-elective neurosurgical cases during the third COVID-19 pandemic wave in Austria, driven by their lower incidence during the first COVID-19 wave in 2020. Selected neurosurgical conditions commonly associated with traumatic etiologies including TBI, and CSDH roughly reverted to similar incidence rates from the previous non-COVID-19 years. Further resisting the major deleterious effects of the continuing COVID-19 pandemic, it is edifying to notice that the neurosurgical community´s demeanor to the recent third pandemic culmination keeps the very high standards of non-elective neurosurgical care alongside with low periprocedural morbidity. This also reflects the current state of health care quality in the Czech Republic and Austria.

Long-Term Outcome After Midline Lumbar Fusion for the Treatment of Lumbar Spine Instability Due to Degenerative Disease.

BACKGROUND: Midline lumbar fusion (MIDLF) is one promising new surgical technique that has been developed to minimize perioperative damage to the paravertebral stabilizing musculotendinous system. The aim of this study was to assess long-term clinical and radiological effects of MIDLF. METHODS: This prospective cohort study evaluated patients who underwent MIDLF for degenerative spinal instability. Clinical and radiological examinations were performed before and after surgery. Perioperative and postoperative complications were recorded. Follow-up was 2 years. P ≤ 0.05 was considered statistically significant. RESULTS: The study included 64 patients (mean age 58.9 ± 10.7 years; 41 women [64.1%]). The most frequent indication for MIDLF was degenerative spondylolisthesis grade I (28 cases [43.8%]); the prevalent spinal segment to be fused was L4-L5 (35 cases [54.7%]). Mean duration of surgery was 148.2 ± 28.9 minutes. Relief of low back pain and leg pain was significant and stable in the postoperative period as assessed by visual analog scale (P < 0.001). Of patients, 86.9% reported fair, good, or excellent outcomes in terms of pain relief based on MacNab score 2 years after surgery. Patients' level of function in activities of daily living improved significantly based on Oswestry Disability Index score: from 66.8 ± 9.8 before surgery to 33.9 ± 16.5 2 years after surgery (P < 0.001). X-rays and computed tomography at 12 months showed interbody fusion in 46 cases (73.4%), inconclusive results in 13 cases (20.3%), and no fusion in 4 cases (6.3%). No damage to neural or vascular structures and no failure of hardware or screw loosening were recorded. CONCLUSIONS: MIDLF is a safe, efficient method for surgical treatment of lumbar spine instability. Its limited invasiveness contributes to better preservation of paravertebral muscles and enhanced postoperative spinal stability.

Trends and outcomes for non-elective neurosurgical procedures in Central Europe during the COVID-19 pandemic.

The world currently faces the novel severe acute respiratory syndrome coronavirus 2 pandemic. Little is known about the effects of a pandemic on non-elective neurosurgical practices, which have continued under modified conditions to reduce the spread of COVID-19. This knowledge might be critical for the ongoing second coronavirus wave and potential restrictions on health care. We aimed to determine the incidence and 30-day mortality rate of various non-elective neurosurgical procedures during the COVID-19 pandemic. A retrospective, multi-centre observational cohort study among neurosurgical centres within Austria, the Czech Republic, and Switzerland was performed. Incidence of neurosurgical emergencies and related 30-day mortality rates were determined for a period reflecting the peak pandemic of the first wave in all participating countries (i.e. March 16th-April 15th, 2020), and compared to the same period in prior years (2017, 2018, and 2019). A total of 4,752 emergency neurosurgical cases were reviewed over a 4-year period. In 2020, during the COVID-19 pandemic, there was a general decline in the incidence of non-elective neurosurgical cases, which was driven by a reduced number of traumatic brain injuries, spine conditions, and chronic subdural hematomas. Thirty-day mortality did not significantly increase overall or for any of the conditions examined during the peak of the pandemic. The neurosurgical community in these three European countries observed a decrease in the incidence of some neurosurgical emergencies with 30-day mortality rates comparable to previous years (2017-2019). Lower incidence of neurosurgical cases is likely related to restrictions placed on mobility within countries, but may also involve delayed patient presentation.

Optic nerve sheath meningioma-findings in the contralateral optic nerve tract: A case report.

The aim of the present study was to observe visual pathway changes on the contralateral side in optic nerve sheath meningioma (ONSM). The authors present a case report of a 43-year-old patient with OfNSM on the right side. A complex ophthalmic examination was performed, including an assessment of visual functions, an electrophysiology examination and functional and structural MRI examinations. Visual acuity of the right eye after ONSM remained with no light perception, while that of the left side was normal. The visual field of the left eye was normal as was colour perception. An electrophysiology examination using a pattern electroretinogram revealed low amplitude values in the right eye. In the left eye, the finding was at the lower limit of normal results. The pattern visual evoked potential exhibited a bilateral lesion with a larger decrease in response after stimulation of the right eye. The structural MRI revealed intraorbital atrophy of the optic nerve on the right side throughout the whole course, which was accompanied by atrophy of the right half of the optic chiasm. Functional magnetic resonance imaging revealed zero activity after stimulation of the right eye and decreased activity in the visual centre after stimulation of the left eye. The present study demonstrated that unilateral damage to the optic nerve in ONSM is accompanied by significant changes on the contralateral side of the optic pathway.

Lower subscapular nerve transfer for axillary nerve repair in upper brachial plexus palsy.

BACKGROUND: The potential to utilize the lower subscapular nerve for brachial plexus surgery has been suggested in many anatomical studies. However, we know of no studies in the literature describing the use of the lower subscapular nerve for axillary nerve reconstruction to date. This study aimed to examine the effectiveness of this nerve transfer in patients with upper brachial plexus palsy. METHODS: Of 1340 nerve reconstructions in 568 patients with brachial plexus injury performed by the senior author (P.H.), a subset of 18 patients underwent axillary nerve reconstruction using the lower subscapular nerve and constitutes the patient group for this study. The median age was 48 years, and the median time between trauma and surgery was 6 months. A concomitant radial nerve injury was found in 8 patients. RESULTS: Thirteen patients completed a minimum follow-up period of 24 months. Successful deltoid recovery was defined as (1) muscle strength MRC grade ≥ 3, (2) electromyographic signs of reinnervation, and (3) increase in deltoid muscle mass. Axillary nerve reconstruction was successful in 9 of 13 patients, which represents a success rate of 69.2%. No significant postoperative weakness of shoulder internal rotation or adduction was observed after transecting the lower subscapular nerve. CONCLUSIONS: The lower subscapular nerve can be used as a safe and effective neurotization tool for upper brachial plexus injury, having a success rate of 69.2% for axillary nerve repair. Our technique presents a suitable alternative for patients with concomitant radial nerve injury.

Leaf Area Index Estimation Using Three Distinct Methods in Pure Deciduous Stands.

Accurate estimations of leaf area index (LAI), defined as half of the total leaf surface area per unit of horizontal ground surface area, are crucial for describing the vegetation structure in the fields of ecology, forestry, and agriculture. Therefore, procedures of three commercially used methods (litter traps, needle technique, and a plant canopy analyzer) for performing LAI estimation were presented step-by-step. Specific methodological approaches were compared, and their current advantages, controversies, challenges, and future perspectives were discussed in this protocol. Litter traps are usually deemed as the reference level. Both the needle technique and the plant canopy analyzer (e.g., LAI-2000) frequently underestimate LAI values in comparison with the reference. The needle technique is easy to use in deciduous stands where the litter completely decomposes each year (e.g., oak and beech stands). However, calibration based on litter traps or direct destructive methods is necessary. The plant canopy analyzer is a commonly used device for performing LAI estimation in ecology, forestry, and agriculture, but is subject to potential error due to foliage clumping and the contribution of woody elements in the field of view (FOV) of the sensor. Eliminating these potential error sources was discussed. The plant canopy analyzer is a very suitable device for performing LAI estimations at the high spatial level, observing a seasonal LAI dynamic, and for long-term monitoring of LAI.

Traumatic optic neuropathy-a contralateral finding: A case report.

The present study demonstrates alterations of the contralateral side optic tract to an optic nerve traumatic lesion. Visual acuity of the right eye following Traumatic optic neuropathy (TON) remained at 0 following the injury. Electrophysiological examination using pattern electroretinogram revealed values reduced by 50% in the right eye compared with the left eye. Pattern visual-evoked potential evaluation indicated a bilateral lesion with a higher decrease following right eye stimulation. Magnetic resonance imaging revealed right optic nerve atrophy. Functional magnetic resonance imaging indicated decreased activity of the visual centre during left eye stimulation. The present study revealed contralateral visual tract alterations following unilateral injury, and hypothesize that the ganglion cells of the retina respond initially to glial activation. These changes are, in our view, followed by changes in the visual pathway.

Preserved cutaneous silent period in cervical root avulsion.

OBJECTIVE: Brachial plexus injuries are usually severe and involve the entire brachial plexus, sometimes occurring with root avulsions. Imaging and electrodiagnostic studies are an essential part of the lesion evaluation; however, the results sometimes show a discrepancy. The cutaneous silent period (SP) is a spinal inhibitory reflex mediated by small-diameter A-delta nociceptive fibers. The aim of the study was to determine if cutaneous SP testing may serve as a useful aid in evaluation of brachial plexus injury and/or in the diagnosis of root avulsion. METHODS: In 19 patients with traumatic brachial plexus injury (15 males, age 18-62 years) we performed a clinical examination, CT myelography and neurophysiological testing. A needle EMG was obtained from muscles supplied by C5-T1 myotomes. Cutaneous SP was recorded after painful stimuli were delivered to the thumb (C6 dermatome), middle (C7) and little (C8) fingers while subjects maintained voluntary contraction of intrinsic hand muscles. RESULTS: Electrodiagnostic and imaging studies confirmed root avulsion (partial or total) maximally involving C5, C6 roots in 12 patients, whereas only in 4 of them the cutaneous SP was partially absent. In the remaining subjects, the cutaneous SP was preserved. CONCLUSION: In brachial plexopathy even with plurisegmental root avulsion, the cutaneous SP was mostly preserved. This method cannot be recommended as a reliable test for diagnosis of single root avulsion; however, it can provide a quick physiological confirmation of functional afferent A-delta fibers through damaged roots and/or trunks. The clinicians may add this test to the diagnosis of spinal cord dysfunction.

Complete diagnostics and clinical approach for a female patient with unusual glioblastoma: A case study.

The present study reports a case of a 44-year-old female patient with a large frontal lobe tumor who underwent surgery using a modern navigation system SonoWand that combines the advantages of a non-frame navigation system with intraoperative real-time ultrasound imaging. The right frontal lobe tumor consisted of two morphologically different sections. A diffuse astrocytoma grade II and a glioblastoma grade IV were identified. These tumors were relatively substantially separated. A 17 p deletion, including TP53, was detected in a diffuse astrocytoma but not in a glioblastoma. EGFR and MDM2 amplifications were detected only in a glioblastoma. Detection of these amplifications is typical for primary glioblastomas. These findings support our assumption of two independent tumors. The KRAS, BRAF and EGFR gene mutations were also detected in a glioblastoma. Such an accumulation of molecular mutations is rare in one tumor. Following oncological treatment the patient was cared for in the oncological center and survived for 15 months after the surgery without any signs of a disease. This is an unusual case, and to the best of our knowledge, is not frequently published in literature.

Results of nerve reconstructions in treatment of obstetrical brachial plexus injuries.

BACKGROUND: The aim of this study was to evaluate the results achieved using various surgical techniques in patients with partial and total obstetrical brachial plexus palsy. METHODS: From 2000 to 2013, 33 patients with obstetrical brachial plexus injury underwent surgery. Twenty had follow-up periods greater than 24 months and met the criteria for inclusion in the study. All patients were evaluated using the Active Movement Scale. RESULTS: The outcomes of different nerve reconstructive procedures including nerve transfers, nerve grafting after neuroma resection and end-to-side neurorrhaphy are presented. The overall success rate in upper plexus birth injury was 80 % in shoulder abduction, 50 % in external rotation and 81.8 % in elbow flexion with median follow-ups of 36 months. Success rate in complete paralysis was 87 % in finger and thumb flexion, 87 % in shoulder abduction and 75 % in elbow flexion; the median follow-up was 46 months. Useful reanimation of the hand was obtained in both patients who underwent end-to-side neurotization. CONCLUSION: Improved function can be obtained in infants with obstetrical brachial plexus injury with early surgical reconstruction.

Usefulness of screening tools in the evaluation of long-term effectiveness of DREZ lesioning in the treatment of neuropathic pain after brachial plexus injury.

BACKGROUND: Despite high success rate of DREZ lesioning in the treatment of intractable central pain, there is still a significant incidence of patients without satisfactory post-operative effect. The aim of the study was to evaluate the long-term effect of DREZ lesioning using both a subjective assessment using a visual analog scale (VAS) to quantify residual pain and an assessment using the screening tool (painDETECT Questionnaire, PD-Q). METHODS: DREZ lesioning was performed in 52 patients from a total 441 cases with brachial plexus injury (11.8%) during a 17-year period (1995-2011). The effect of surgery was retrospectively assessed in 48 patients. RESULTS: A decrease in pre-operative pain by more than 75% (Group I) was achieved in 70.8% of patients and another 20.8% reported significant improvement (Group II). The surgery was unsucessful in 8.4% (Group III). We found a significant correlation between 'improvement' groups from both methods of assessments. Patients from Group I usually complained of residual nociceptive pain according to PD-Q, patients from Group II typically had pain of unclear origin, and all cases those in Group III suffered from neuropathic pain, Cramer's V = .66, P < .001. Overall, 66.7% of patients had resolved neuropathic pain, 20.8% patients had more serious complaints and may also suffer from residual neuropathic pain, while 12.5% had unresolved neuropathic pain. CONCLUSION: DREZ lesioning is a safe and effective method with success rates of about 90%. PD-Q scores correspond to subjective satisfaction with the surgery and it seems to be a suitable screening tool for finding patients with residual neuropathic pain after surgery.

Injuries associated with serious brachial plexus involvement in polytrauma among patients requiring surgical repair.

BACKGROUND: Brachial plexus injury occurs in up to 5% of polytrauma cases involving motorcycle crashes and in approximately 4% of severe winter sports injuries. One of the conditions for the success of operative therapy is early detection, ideally within three months of injury. The aim of this study was to evaluate associated injuries in patients with severe brachial plexus injury and determine whether there is a characteristic concomitant injury (or injuries), the presence of which, in the polytrauma, could act as a marker for nerve structures involvement and whether there are differences in severity of polytrauma accompanying specific types of brachial plexus injury. METHODS: We evaluated retrospectively 84 surgical patients from our department, from 2008 to 2011, that had undergone brachial plexus reconstruction. For all, an injury severity scale (ISS) score and all major associated injuries were determined. RESULTS: 72% of patients had an upper, 26% had a complete and only 2% had a lower brachial plexus palsy. The main cause was motorcycle crashes (60%) followed by car crashes (15%). The average ISS was 35.2 (SD=23.3), although, values were significantly higher in cases involving a coma (59.3, SD=11.0). The lower and complete plexus injuries were significantly associated with coma and fractures of the shoulder girdle and injuries of lower limbs, thoracic organs and head. Upper plexus injuries were associated with somewhat less severe injuries of the upper and lower extremities and less severe injuries of the spine. CONCLUSION: Serious brachial plexus injury is usually accompanied by other severe injuries. It occurs in high-energy trauma and it can be stated that patients involved in motorcycle and car crashes with multiple fractures of the shoulder girdle are at high risk of nerve trauma. This is especially true for patients in a primary coma. Lower and complete brachial plexus injuries are associated with higher injury severity scale.

End-to-side neurorrhaphy in brachial plexus reconstruction.

OBJECT: Although a number of theoretical and experimental studies dealing with end-to-side neurorrhaphy (ETSN) have been published to date, there is still a considerable lack of clinical trials investigating this technique. Here, the authors describe their experience with ETSN in axillary and musculocutaneous nerve reconstruction in patients with brachial plexus palsy. METHODS: From 1999 to 2007, out of 791 reconstructed nerves in 441 patients treated for brachial plexus injury, the authors performed 21 axillary and 2 musculocutaneous nerve sutures onto the median, ulnar, or radial nerves. This technique was only performed in patients whose donor nerves, such as the thoracodorsal and medial pectoral nerves, which the authors generally use for repair of axillary and musculocutaneous nerves, respectively, were not available. In all patients, a perineurial suture was carried out after the creation of a perineurial window. RESULTS: The overall success rate of the ETSN was 43.5%. Reinnervation of the deltoid muscle with axillary nerve suture was successful in 47.6% of the patients, but reinnervation of the biceps muscle was unsuccessful in the 2 patients undergoing musculocutaneous nerve repair. CONCLUSIONS: The authors conclude that ETSN should be performed in axillary nerve reconstruction but only when commonly used donor nerves are not available.

Serious axillary nerve injury caused by subscapular artery compression resulting from use of backpacks.

A palsy of the brachial plexus elements caused by carrying a heavy backpack is a very rare injury usually occurring in soldiers or hikers, and recovery is usually spontaneous. We describe here the case of male civilian presenting with an isolated serious axillary nerve palsy associated with chronic backpack use. During the surgery, a dumbbell-shaped neuroma-in-continuity was found which was caused by direct pressure from the subscapular artery. After resection of the neuroma, a nerve graft from the sural nerve was used to reconstruct the nerve. Reinnervation was successful and the patient was able to abduct his arm to its full range, with full muscle strength, within 24 months.

A Comparison of collateral sprouting of sensory and motor axons after end-to-side neurorrhaphy with and without the perineurial window.

BACKGROUND: Many experimental studies have confirmed collateral sprouting of axons after end-to-side neurorrhaphy and its possible clinical application. There is still controversy about how the surgical method should be carried out. The aim of the present study was to quantitatively evaluate collateral sprouting of motor and sensory axons after end-to-side neurorrhaphy with and without the perineurial window. METHODS: End-to-side neurorrhaphy of the distal stump of transected musculocutaneous nerve with intact ulnar nerve with or without a perineurial window was performed in a rat model. Collateral sprouts were quantitatively evaluated by counting of motor and sensory neurons following their retrograde labeling by Fluoro-Ruby and Fluoro-Emerald applied to the ulnar and musculocutaneous nerves, respectively. RESULTS: Our results show that significantly more motor and sensory axons sent their collateral branches into the recipient nerve in the group with a perineurial window. Some axons were injured during preparation of the perineurial window; the injured axons reinnervated directly into the recipient nerve to contribute to results of functional reinnervation. CONCLUSION: The authors conclude that it is necessary to create a perineurial window when using end-to-side neurorrhaphy in clinical practice, especially in brachial plexus reconstruction.

Axillary nerve repair by fascicle transfer from the ulnar or median nerve in upper brachial plexus palsy.

OBJECT: Nerve repair using motor fascicles of a different nerve was first described for the repair of elbow flexion (Oberlin technique). In this paper, the authors describe their experience with a similar method for axillary nerve reconstruction in cases of upper brachial plexus palsy. METHODS: Of 791 nerve reconstructions performed by the senior author (P.H.) between 1993 and 2011 in 441 patients with brachial plexus injury, 14 involved axillary nerve repair by fascicle transfer from the ulnar or median nerve. All 14 of these procedures were performed between 2007 and 2010. This technique was used only when there was a deficit of the thoracodorsal or long thoracic nerve, which are normally used as donors. RESULTS: Nine patients were followed up for 24 months or longer. Good recovery of deltoid muscle strength was seen in 7 (77.8%) of these 9 patients, and in 4 patients with less follow-up (14-23 months), for an overall success rate of 78.6%. The procedure was unsuccessful in 2 of the 9 patients with at least 24 months of follow-up. The first showed no signs of reinnervation of the axillary nerve by either clinical or electromyographic evaluation in 26 months of follow-up, and the second had Medical Research Council (MRC) Grade 2 strength in the deltoid muscle 36 months after the operation. The last of the group of 14 patients has had 12 months of follow-up and is showing progressive improvement of deltoid muscle function (MRC Grade 2). CONCLUSIONS: The authors conclude that fascicle transfer from the ulnar or median nerve onto the axillary nerve is a safe and effective method for reconstruction of the axillary nerve in patients with upper brachial plexus injury.

The influence of seatbelts on the types of operated brachial plexus lesions caused by car accidents.

PURPOSE: To determine whether there is a relationship between seatbelt use and type of brachial plexus injury seen in automobile accidents. Knowledge of such a relationship may help guide the surgical management of these patients. METHODS: We retrospectively evaluated 43 surgical patients with brachial plexus palsy caused by car accidents. We recorded sex, age, and type of injury for each case. We also obtained data regarding the patients' position in the car at the time of the accident and whether they were wearing a seatbelt. RESULTS: We obtained data on 39 men and 4 women. Of the seatbelted patients, 24 (100%) had upper plexus palsy on the side where the seatbelt crossed the shoulder. Of those who were not wearing seatbelts, 17 (86%) had complete plexus injuries. We also found 1 upper and 1 lower plexus injury in the unbelted group. CONCLUSIONS: We found a relationship between the type of brachial plexus injury sustained by the accident victim and the use and position of the seatbelt. Complete plexus injuries were more common in those who were not wearing seatbelts. We saw upper plexus injuries for those wearing seatbelts. Information about seatbelt use may be useful in clinical practice. When treating an unbelted car accident victim with a brachial plexus injury, it is reasonable to anticipate a more serious form of the injury. TYPE OF STUDY/LEVEL OF EVIDENCE: Prognostic IV.

Enhancement of musculocutaneous nerve reinnervation after vascular endothelial growth factor (VEGF) gene therapy.

BACKGROUND: Vascular endothelial growth factor (VEGF) is not only a potent angiogenic factor but it also promotes axonal outgrowth and proliferation of Schwann cells. The aim of the present study was to quantitatively assess reinnervation of musculocutaneous nerve (MCN) stumps using motor and primary sensory neurons after plasmid phVEGF transfection and end-to-end (ETE) or end-to-side (ETS) neurorrhaphy. The distal stump of rat transected MCN, was transfected with plasmid phVEGF, plasmid alone or treated with vehiculum and reinnervated following ETE or ETS neurorrhaphy for 2 months. The number of motor and dorsal root ganglia neurons reinnervating the MCN stump was estimated following their retrograde labeling with Fluoro-Ruby and Fluoro-Emerald. Reinnervation of the MCN stumps was assessed based on density, diameter and myelin sheath thickness of regenerated axons, grooming test and the wet weight index of the biceps brachii muscles. RESULTS: Immunohistochemical detection under the same conditions revealed increased VEGF in the Schwann cells of the MCN stumps transfected with the plasmid phVEGF, as opposed to control stumps transfected with only the plasmid or treated with vehiculum. The MCN stumps transfected with the plasmid phVEGF were reinnervated by moderately higher numbers of motor and sensory neurons after ETE neurorrhaphy compared with control stumps. However, morphometric quality of myelinated axons, grooming test and the wet weight index were significantly better in the MCN plasmid phVEGF transfected stumps. The ETS neurorrhaphy of the MCN plasmid phVEGF transfected stumps in comparison with control stumps resulted in significant elevation of motor and sensory neurons that reinnervated the MCN. Especially noteworthy was the increased numbers of neurons that sent out collateral sprouts into the MCN stumps. Similarly to ETE neurorrhaphy, phVEGF transfection resulted in significantly higher morphometric quality of myelinated axons, behavioral test and the wet weight index of the biceps brachii muscles. CONCLUSION: Our results showed that plasmid phVEGF transfection of MCN stumps could induce an increase in VEGF protein in Schwann cells, which resulted in higher quality axon reinnervation after both ETE and ETS neurorrhaphy. This was also associated with a better wet weight biceps brachii muscle index and functional tests than in control rats.