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Fischmeister FPS, Amini A, Matt E, Reinecke R, Schmidhammer R, Beisteiner R. A New Rehabilitative Mechanism in Primary Motor Cortex After Peripheral Trauma. Front Neurol 2020; 11:125. [PMID: 32174882 PMCID: PMC7056825 DOI: 10.3389/fneur.2020.00125] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Accepted: 02/04/2020] [Indexed: 12/21/2022] Open
Abstract
Homuncular organization, i.e., the neuronal representation of the human body within the primary motor cortex, is one of the most fundamental principles of the human brain. Despite this, in rare peripheral nerve surgery patients, the transformation of a monofunctional (diaphragm activation) into a bifunctional motor area (diaphragm and arm activation is controlled by the same cortical area) has previously been demonstrated. The mechanisms behind this transformation are not fully known. To investigate this transformation of a monofunctional area we investigate functional connectivity changes in a unique and highly instructive pathophysiological patient model. These patients suffer from complete brachial plexus avulsion with arm paralysis and had been treated with reconnection of the end of the musculocutaneous nerve to the side of a fully functional phrenic nerve to regain function. Task-based functional connectivity between the arm representations and the diaphragm (phrenic nerve) representations were examined in six patients and 12 aged matched healthy controls at ultra-high field MRI while they either performed or tried isolated elbow flexion or conducted forced abdominal inspiration. Functional connectivity values are considerably increased between the diseased arm and the bilateral diaphragm areas while trying strong muscle tension in the diseased arm as compared to the healthy arm. This effect was not found as compared to the healthy arm in the patient group. This connectivity was stronger between ipsilateral than between corresponding contralateral brain regions. No corresponding differences were found in healthy subjects. Our data suggests that the increased functional connectivity between the deprived arm area and the diaphragm area drives biceps muscle function. From this findings we infer that this new rehabilitative mechanism in the primary motor cortex may establish new intrahemispheric connections within the brain and the motor cortex in particular to reroute the output of a completely denervated motor area. This study extend current knowledge about neuroplasticity within the motor cortex.
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Affiliation(s)
- Florian Ph S Fischmeister
- Study Group Clinical fMRI, Department of Neurology, Medical University of Vienna, Vienna, Austria.,Highfield MR Centre, Medical University of Vienna, Vienna, Austria.,Department of Psychology, University of Graz, Graz, Austria.,Ludwig Boltzmann Institute for Experimental and Clinical Traumatology, Vienna, Austria
| | - Ahmad Amini
- Study Group Clinical fMRI, Department of Neurology, Medical University of Vienna, Vienna, Austria.,Highfield MR Centre, Medical University of Vienna, Vienna, Austria
| | - Eva Matt
- Study Group Clinical fMRI, Department of Neurology, Medical University of Vienna, Vienna, Austria.,Highfield MR Centre, Medical University of Vienna, Vienna, Austria
| | - Raphael Reinecke
- Study Group Clinical fMRI, Department of Neurology, Medical University of Vienna, Vienna, Austria.,Highfield MR Centre, Medical University of Vienna, Vienna, Austria
| | - Robert Schmidhammer
- Ludwig Boltzmann Institute for Experimental and Clinical Traumatology, Vienna, Austria
| | - Roland Beisteiner
- Study Group Clinical fMRI, Department of Neurology, Medical University of Vienna, Vienna, Austria.,Highfield MR Centre, Medical University of Vienna, Vienna, Austria
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Amini A, Fischmeister FPS, Matt E, Schmidhammer R, Rattay F, Beisteiner R. Peripheral Nervous System Reconstruction Reroutes Cortical Motor Output-Brain Reorganization Uncovered by Effective Connectivity. Front Neurol 2019; 9:1116. [PMID: 30619069 PMCID: PMC6305497 DOI: 10.3389/fneur.2018.01116] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Accepted: 12/05/2018] [Indexed: 01/30/2023] Open
Abstract
Cortical reorganization in response to peripheral nervous system damage is only poorly understood. In patients with complete brachial plexus avulsion and subsequent reconnection of the end of the musculocutaneous nerve to the side of a phrenic nerve, reorganization leads to a doubled arm representation in the primary motor cortex. Despite, homuncular organization being one of the most fundamental principles of the human brain, movements of the affected arm now activate 2 loci: the completely denervated arm representation and the diaphragm representation. Here, we investigate the details behind this peripherally triggered reorganization, which happens in healthy brains. fMRI effective connectivity changes within the motor network were compared between a group of patients and age matched healthy controls at 7 Tesla (6 patients and 12 healthy controls). Results show the establishment of a driving input of the denervated arm area to the diaphragm area which is now responsible for arm movements. The findings extend current knowledge about neuroplasticity in primary motor cortex: a denervated motor area may drive an auxilliary area to reroute its motor output.
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Affiliation(s)
- Ahmad Amini
- Study Group Clinical fMRI, Department of Neurology, Medical University of Vienna, Vienna, Austria.,Highfield MR Centre, Medical University of Vienna, Vienna, Austria.,TU-BioMed Association for Biomedical Engineering, Vienna University of Technology, Vienna, Austria
| | - Florian Ph S Fischmeister
- Study Group Clinical fMRI, Department of Neurology, Medical University of Vienna, Vienna, Austria.,Highfield MR Centre, Medical University of Vienna, Vienna, Austria.,Institute of Psychology, University of Graz, Graz, Austria
| | - Eva Matt
- Study Group Clinical fMRI, Department of Neurology, Medical University of Vienna, Vienna, Austria.,Highfield MR Centre, Medical University of Vienna, Vienna, Austria
| | - Robert Schmidhammer
- Ludwig Boltzmann Institute for Experimental and Clinical Traumatology, Vienna, Austria
| | - Frank Rattay
- TU-BioMed Association for Biomedical Engineering, Vienna University of Technology, Vienna, Austria
| | - Roland Beisteiner
- Study Group Clinical fMRI, Department of Neurology, Medical University of Vienna, Vienna, Austria.,Highfield MR Centre, Medical University of Vienna, Vienna, Austria
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Methylcobalamin facilitates collateral sprouting of donor axons and innervation of recipient muscle in end-to-side neurorrhaphy in rats. PLoS One 2013; 8:e76302. [PMID: 24098787 PMCID: PMC3786991 DOI: 10.1371/journal.pone.0076302] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Accepted: 08/23/2013] [Indexed: 12/28/2022] Open
Abstract
Using ulnar nerve as donor and musculocutaneous nerve as recipient we found earlier that end-to-side neurorrhaphy resulted in weak functional reinnervation after lengthy survival. End-to-side neurorrhaphy however is the sole choice of nerve repair at times and has the advantage of conserving donor nerve function. Here, we investigated whether myelination-enhancing agent methylcobalamin and motoneuron trophic factor pleiotrophin enhances the recovery after end-to-side neurorrhaphy. Methylcobalamin significantly increased the expression of growth associated protein 43 and S100 protein and βIII tubulin in musculocutaneous nerve 1 month after neurorrhaphy suggesting the ingrowth of ulnar axonal sprouts in reactive Schwann cell environment. Upper limb functional test, compound muscle action potential measurements, motor end plate counts, and axon and myelin analyses showed that methylcobalamin treatment alone or with pleiotrophin improved the recovery significantly, 3 and 6 months post-surgery. There were fewer axons, closer in number to that of the intact recipient nerve, found in the distal repaired nerve of the methylcobalamin-treated than that of the vehicle control, suggesting that methylcobalamin facilitates axonal maturation and eliminates supernumerary sprouts. In conclusion, our results showed that methylcobalamin does indeed enhance the recovery of peripheral nerve repaired in end-to-side configuration.
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Haninec P, Mencl L, Kaiser R. End-to-side neurorrhaphy in brachial plexus reconstruction. J Neurosurg 2013; 119:689-94. [DOI: 10.3171/2013.6.jns122211] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
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.
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Kovačič U, Zele T, Tomšič M, Sketelj J, Bajrović FF. Influence of breaching the connective sheaths of the donor nerve on its myelinated sensory axons and on their sprouting into the end-to-side coapted nerve in the rat. J Neurotrauma 2012; 29:2805-15. [PMID: 22873667 DOI: 10.1089/neu.2011.2298] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The influence of breaching the connective sheaths of the donor sural nerve on axonal sprouting into the end-to-side coapted peroneal nerve was examined in the rat. In parallel, the effect of these procedures on the donor nerve was assessed. The sheaths of the donor nerve at the coaptation site were either left completely intact (group A) or they were breached by epineurial sutures (group B), an epineurial window (group C), or a perineurial window (group D). In group A, the compound action potential (CAP) of sensory axons was detected in ~10% and 40% of the recipient nerves at 4 and 8 weeks, respectively, which was significantly less frequently than in group D at both recovery periods. In addition, the number of myelinated axons in the recipient nerve was significantly larger in group D than in other groups at 4 weeks. At 8 weeks, the number of axons in group A was only ~15% of the axon numbers in other groups (p<0.05). Focal subepineurial degenerative changes in the donor nerves were only seen after 4 weeks, but not later. The average CAP area and the total number of myelinated axons in the donor nerves were not different among the experimental groups. In conclusion, myelinated sensory axons are able to penetrate the epiperineurium of donor nerves after end-to-side nerve coaption; however, their ingrowth into recipient nerves is significantly enhanced by breaching the epiperineurial sheets at the coaptation site. Breaching does not cause permanent injury to the donor nerve.
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Affiliation(s)
- Uroš Kovačič
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Slovenia.
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Yu Q, Lin ZK, Ding J, Wang T, Chi YL, Gao WY. Functional motor nerve regeneration without motor-sensory specificity following end-to-side neurorrhaphy: an experimental study. J Hand Surg Am 2011; 36:2010-6. [PMID: 22123048 DOI: 10.1016/j.jhsa.2011.09.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2011] [Revised: 09/13/2011] [Accepted: 09/13/2011] [Indexed: 02/02/2023]
Abstract
PURPOSE To evaluate the quality of regenerating myelinated axons and motor-sensory specificity in an end-to-side nerve repair model. METHODS We divided 20 rats into 3 groups: (1) end-to-side neurorrhaphy using the ulnar nerve as donor nerve and the musculocutaneous nerve as recipient nerve; (2) normal control; and (3) transected nerve with the stumps buried. At 5 months, we monitored the grooming test, the electrophysiological response, and the histologic changes in nerve and muscle. RESULTS Grooming recovered successfully, and electrophysiological investigations revealed that the target muscles had been reinnervated in the end-to-side group. The mean wet weight of the reinnervated biceps brachii muscle was 72% of the normal muscle, and the mean muscle fiber cross-sectional area of the reinnervated muscle was similar to the normal muscle. The implanted musculocutaneous nerve contained varying but satisfactory numbers of axons (end-to-side group: 596 ± 348 vs normal group: 1,340 ± 241). Acetylcholinesterase staining revealed a similar percentage of myelinated fibers in the musculocutaneous nerve (39%) and the biceps brachii branch of the musculocutaneous nerve (38%) in the end-to-side group. This was similar to the number of myelinated fibers in the donor ulnar nerve (37%). CONCLUSIONS The present study confirms that limited but functional reinnervation can occur on the basis of collateral sprouting of intact axons from the ulnar nerve. The motor-sensory specificity is not important.
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Affiliation(s)
- Qing Yu
- Department of Orthopaedic Surgery, Second Affiliated Hospital of Wenzhou Medical College, Zhejiang, China
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Ozsoy U, Hizay A, Demirel BM, Ozsoy O, Bilmen Sarikcioglu S, Turhan M, Sarikcioglu L. The hypoglossal–facial nerve repair as a method to improve recovery of motor function after facial nerve injury. Ann Anat 2011; 193:304-13. [PMID: 21458251 DOI: 10.1016/j.aanat.2011.01.009] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2010] [Revised: 01/03/2011] [Accepted: 01/05/2011] [Indexed: 12/16/2022]
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