Anatomical feasibility of using the ninth, 10th, and 11th intercostal nerves for the treatment of neurological deficits after damage to the spinal cord

Anatomical feasibility of anastomosing intercostal nerves (D10&D11) and subcostal nerve (D12) to S2 ventral root and lumbar plexus for management of bladder function after spinal cord injury

OBJECTIVE

The transfer of peripheral nerves originating above the level of injured spinal cord into the nerves/roots below the injury is a promising approach. It facilitates the functional recovery in lower extremity, bladder/bowel and sexual function in paraplegics. We assessed anatomical feasibility of transfer of lower intercostal nerves to S2 ventral root in human cadaver for management of neurogenic bladder dysfunction in patients with spinal cord injury.

METHODS

Study was performed in five formalin fixed cadavers. Cadavers were placed in prone position. A transverse incision was made along 11th ribs on both sides and 10th, 11th Intercostal nerves (ICN) and subcostal nerve were harvested up to maximum possible length. In four cadavers the ventral root of S2 was exposed by endoscope and in one by the standard open laminectomy. Intercostal nerves were brought down to lumbo-sacral region, S2 ventral root was cut cranially and feasibility of intercostal to S2 anastomosis was assessed.

RESULTS

The mean length of intercostal nerves was 18.4 cm for the 10th 19.5 cm for the 11th and 22.15 cm for the subcostal nerve. The length of harvested nerve and the nerve length necessary to perform sacral roots neurotization were possible in all cases by only by subcostal nerve while T11 and T10 ICN fall short of the required length.

CONCLUSION

For Spinal cord lesions located at the conus, subcostal nerve could be connected to ventral root of S2 in an attempt to restore bladder function while 10th and 11th ICN had enough length to neurotize lumbar plexus.

Intercostal, ilioinguinal, and iliohypogastric nerve transfers for lower limb reinnervation after spinal cord injury: an anatomical feasibility and experimental study

OBJECTIVESpinal cord injury (SCI) has been investigated in various animal studies. One promising therapeutic approach involves the transfer of peripheral nerves originating above the level of injury into those originating below the level of injury. The purpose of the present study was to evaluate the feasibility of nerve transfers for reinnervation of lower limbs in patients suffering SCI to restore some hip and knee functions, enabling them to independently stand or even step forward with assistive devices and thus improve their quality of life.METHODSThe feasibility of transferring intercostal to gluteal nerves and the ilioinguinal and iliohypogastric nerves to femoral nerves was assessed in 5 cadavers. Then, lumbar cord hemitransection was performed below L1 in 20 dogs, followed by transfer of the 10th, 11th, and 12th intercostal and subcostal nerves to gluteal nerves and the ilioinguinal and iliohypogastric nerves to the femoral nerve in only 10 dogs (NT group). At 6 months, clinical and electrophysiological evaluations of the recipient nerves and their motor targets were performed.RESULTSThe donor nerves had sufficient length to reach the recipient nerves in a tension-free manner. At 6 months postoperatively, the mean conduction velocity of gluteal and femoral nerves, respectively, increased to 96.1% and 92.8% of the velocity in controls, and there was significant motor recovery of the quadriceps femoris and glutei.CONCLUSIONSIntercostal, ilioinguinal, and iliohypogastric nerves are suitable donors to transfer to the gluteal and femoral nerves after SCI to restore some hip and knee motor functions.

Anatomic conditions for bypass surgery between rostral (T7-T9) and caudal (L2, L4, S1) ventral roots to treat paralysis after spinal cord injury

Severe spinal cord injuries cause permanent neurological deficits and are still considered as inaccessible to efficient therapy. Injured spinal cord axons are unable to spontaneously regenerate. Re-establishing functional activity especially in the lower limbs by reinnervation of the caudal infra-lesional territories might represent an effective therapeutic strategy. Numerous surgical neurotizations have been developed to bridge the spinal cord lesion site and connect the intact supra-lesional portions of the spinal cord to peripheral nerves (spinal nerves, intercostal nerves) and muscles. The major disadvantage of these techniques is the increased hypersensitivity, spasticity and pathologic pain in the spinal cord injured patients, which occur due to the vigorous sprouting of injured afferent sensory fibers after reconstructive surgery. Using micro-surgical instruments and an operation microscope we performed detailed anatomical preparation of the vertebral canal and its content in five human cadavers. Our observations allow us to put forward the possibility to develop a more precise surgical approach, the so called "ventral root bypass" that avoids lesion of the dorsal roots and eliminates sensitivity complications. The proposed kind of neurotization has been neither used, nor put forward. The general opinion is that radix ventralis and radix dorsalis unite to form the spinal nerve inside the dural sac. This assumption is not accurate, because both radices leave the dural sac separately. This neglected anatomical feature allows a reliable intravertebral exposure of the dura-mater ensheathed ventral roots and their damage-preventing end-to-side neurorrhaphy by interpositional nerve grafts.

Orthopaedic surgery for patients with central nervous system lesions: Concepts and techniques

Since ancient times, the aim of orthopedic surgery has been to correct limb and joint deformities, including those resulting from central nervous system lesions. Recent developments in the treatment of spasticity have led to changes in concepts and management strategies. The increase in life expectancy has increased the functional needs of patients. Orthopedic surgery, along with treatments for spasticity, improves the functional capacity of patients with neuro-orthopaedic disorders, improving their autonomy. In this paper, we describe key moments in the history of orthopedic surgery regarding the treatment of patients with central nervous system lesions, from poliomyelitis to stroke-related hemiplegia, from the limbs to the spine, and from contractures to heterotopic ossification. A synthesis of the current surgical techniques is then provided, and the importance of multidisciplinary evaluation and management is highlighted, along with indications for medical, rehabilitation and surgical treatments and their combinations. We explain why it is essential to consider patients' expectations and to set achievable goals, particularly before surgery, which is by nature irreversible. More recently, specialized surgical teams have begun to favor the use of soft-tissue techniques over bony and joint procedures, except for spinal disorders. We highlight that orthopedic surgery is no longer the end-point of treatment. For example, lengthening a contractured muscle improves the balance around a joint, improving mobility and stability but may be only part of the problem. Further medical treatment and rehabilitation, or additional surgery, are often necessary to continue to improve the function of the limb. Despite the recognized effectiveness of orthopedic surgery for neuro-orthopedic disorders, few studies have formally evaluated them. Hence, there is a need for research to provide evidence to support orthopedic surgery for treating neuro-orthopedic disorders.

Effective reinnervation of the quadriceps femoris by spinal ventral root cross-anastomosis in rats

PURPOSE: To study the effective recovery of the quadriceps femoris by spinal ventral root cross-anastomosis in rats. METHODS: End-to-end anastomosis was performed between the left L1 and L3 ventral roots using autogenous nerve graft ,and the right L1 and L3 roots were left intact. In control animals, the left L3 ventral root was cut and shortened, and anastomosis was not performed. Six months postoperatively, the movement of low extremities was detected by electrophysiological examination, hindlimb locomotion and basso, beattie and bresnahan (BBB) scoring at one, three, seven, 14, 21 and 28 days after SCI. Fluorescence retrograde tracing with TRUE BLUE (TB) and HE staining were performed to observe the nerve regeneration. RESULTS: Six months after surgery, the anastomotic nerve was smooth and not atrophic. The amplitudes of action potential were 7.63±1.86 mV and 6.0±1.92 mV respectively before and after the spinal cord hemisection. The contraction of left quadriceps femoris was induced by a single stimulation of the anastomotic nerve. The locomotion of left hindlimb was partially restored after spinal cord hemisection while creeping and climbing. In addition, there was significant difference in the BBB score at one, three and seven days after SCI. TB retrograde tracing and neurophysiologic observation indicated efficient reinnervation of the quadriceps femoris. CONCLUSION: The cross-anastomosis between spinal ventral root can partially reconstruct the function of quadriceps femoris following SCI and may have clinical implication for the treatment of human SCI.

Spinal cord bypass surgery with intercostal and spinal accessory nerves: an anatomical feasibility study in human cadavers

OBJECT

Despite extensive study, no meaningful progress has been made in encouraging healing and recovery across the site of spinal cord injury (SCI) in humans. Spinal cord bypass surgery is an unconventional strategy in which intact peripheral nerves rostral to the level of injury are transferred into the spinal cord below the injury. This report details the feasibility of using spinal accessory nerves to bypass cervical SCI and intercostal nerves to bypass thoracolumbar SCI in human cadavers.

METHODS

Twenty-three human cadavers underwent cervical and/or lumbar laminectomy and dural opening to expose the cervical cord and/or conus medullaris. Spinal accessory nerves were harvested from the Erb point to the origin of the nerve's first major branch into the trapezius. Intercostal nerves from the T6-12 levels were dissected from the lateral border of paraspinal muscles to the posterior axillary line. The distal ends of dissected nerves were then transferred medially and sequentially inserted 4 mm deep into the ipsilateral cervical cord (spinal accessory nerve) or conus medullaris (intercostals). The length of each transferred nerve was measured, and representative distal and proximal cross-sections were preserved for axonal counting.

RESULTS

Spinal accessory nerves were consistently of sufficient length to be transferred to caudal cervical spinal cord levels (C4-8). Similarly, intercostal nerves (from T-7 to T-12) were of sufficient length to be transferred in a tension-free manner to the conus medullaris. Spinal accessory data revealed an average harvested nerve length of 15.85 cm with the average length needed to reach C4-8 of 4.7, 5.9, 6.5, 7.1, and 7.8 cm. The average length of available intercostal nerve from each thoracic level compared with the average length required to reach the conus medullaris in a tension-free manner was determined to be as follows (available, required in cm): T-7 (18.0, 14.5), T-8 (18.7, 11.7), T-9 (18.8, 9.0), T-10 (19.6, 7.0), T-11 (18.8, 4.6), and T-12 (15.8, 1.5). The number of myelinated axons present on cross-sectional analysis predictably decreased along both spinal accessory and intercostal nerves as they coursed distally.

CONCLUSIONS

Both spinal accessory and intercostal nerves, accessible from a posterior approach in the prone position, can be successfully harvested and transferred to their respective targets in the cervical spinal cord and conus medullaris. As expected, the number of axons available to grow into the spinal cord diminishes distally along each nerve. To maximize axon "bandwidth" in nerve bypass procedures, the most proximal section of the nerve that can be transferred in a tension-free manner to a spinal level caudal to the level of injury should be implanted. This study supports the feasibility of SAN and intercostal nerve transfer as a means of treating SCI and may assist in the preoperative selection of candidates for future human clinical trials of cervical and thoracolumbar SCI bypass surgery.

Spinal cord bypass surgery using peripheral nerve transfers: review of translational studies and a case report on its use following complete spinal cord injury in a human. Experimental article

Spinal cord injury has been studied in a variety of in vitro and in vivo animal models. One promising therapeutic approach involves the transfer of peripheral nerves originating above the level of injury into the spinal cord below the level of injury. A model of spinal cord injury in rodents has shown the growth of peripheral nerve fibers into the spinal cord, with the subsequent development of functional synaptic connections and limb movement. The authors of this paper are currently developing a similar model in felines to assess the cortical control of these novel repair pathways. In an effort to determine whether these neurotization techniques could translate to spinal cord injury in humans, the authors treated a patient by using intercostal nerve transfer following complete acute spinal cord injury. The case presented details a patient with paraplegia who regained partial motor and sensory activity following the transfer of intercostal nerves, originating above the level of the spinal cord injury, into the spinal canal below the level of injury. The patient recovered some of his motor and sensory function. Notably, his recovered hip flexion showed respiratory variation. This finding raises the possibility that intercostal nerve transfers may augment neurological recovery after complete spinal cord injury.

The paraspinal splitting approach: a possible approach to perform multiple intercosto-lumbar neurotizations: an anatomic study

STUDY DESIGN

Descriptive anatomy. OBJECTIVE.: To describe the anatomy associated with the extensive transmuscular paraspinal approach required to perform multiple intercosto-lumbar neurotizations.

SUMMARY OF BACKGROUND DATA

Neurotization of lumbar roots using lower intercostal nerves is a potential method of treating neurologic deficits after spinal cord injury. It appeared to us that the paraspinal splitting approach was potentially an optimal method to perform intercostal nerve harvesting, rerouting, and intercosto-lumbar neurotizations.

METHODS

Ninth, 10th, and 11th intercostal nerve harvesting and rerouting down to L2, L3, and L4 roots were performed on 50 cadavers. The descriptive anatomy and topographic landmarks are reported.

RESULTS

The mean total length of intercostal nerve harvested was 17.96 (range, 10-27) cm for the 9th intercostal nerve, 17.14 cm (range, 10-20) for the 10th intercostal nerve and 15.94 cm (range, 10-25) for the 11th intercostal nerve. The length of harvested nerve was not correlated to the size of the trunk. The length of harvested nerve was sufficient to perform lumbar roots neurotizations in the 300 cases of nerve harvesting.

CONCLUSION

Multiple lumbar roots neurotizations with lower intercostal nerves already have been proposed by other authors. In this strategy, the use of the spinal cord and intercostal nerves above the spinal cord lesion avoids the axonal regrowth required via the injured central nervous system. Rerouting intercostals nerves down to the lumbar roots at their exit from the intervertebral foraminae is less invasive that the same procedure performed down to the vertebral canal at the level of the cauda equina as we used in previous protocols. Our anatomic study confirms the advantage of the paraspinal sacrospinalis splitting approach in multiple intercosto-lumbar neurotizations. The approach is quick and easy and allows a good exposure of the nerve roots at the thoracic and lumbar levels. The L2, L3, and L4 roots could be satisfactorily neurotized with this procedure.