Nerve Root Avulsion Research Articles

Experimental studies on surgical treatment of avulsed spinal nerve roots in brachial plexus injury

This review summarises studies aiming at a surgical treatment of spinal nerve root avulsions from the spinal cord in brachial plexus lesions. After dorsal root injury, regrowth of nerve fibres into the spinal cord occurs only in the immature animal. After ventral root avulsion and subsequent implantation into the spinal cord, neuroanatomical and neurophysiological data show that motoneurons are capable of producing new axons which enter the implanted root. Intra-neuronal physiological experiments demonstrate that new axons can conduct action potentials and elicit muscle responses. The neurons are reconnected in segmental spinal cord activity and respond to impulses in sensory nerve fibres. In primate experiments, implantation of avulsed ventral roots in the brachial plexus resulted in functional restitution. These studies indicate the possibility of surgical treatment of ventral root avulsion injuries in brachial plexus lesions in humans.

Nerve root avulsion of birth palsy: comparison of myelography with CT myelography and somatosensory evoked potential.

Findings at myelography and computed tomographic (CT) myelography were reviewed in 21 patients (22 limbs) with birth palsy; nerve root shadows were the focus of this study. Myelography demonstrated 51 completely avulsed roots (78%) and 14 incompletely avulsed roots (22%). A traumatic meningocele was detected at 38 roots on myelograms and 51 roots on CT myelograms. Thirteen avulsed roots (eight completely and five incompletely avulsed roots) (20%) were not associated with a meningocele. In nine patients who underwent brachial plexus exploration, myelographic findings were compared with root somatosensory evoked potential (SEP). SEP was not induced at 22 of 25 completely avulsed roots and was induced at all seven incompletely avulsed roots. Myelography and SEP were consistent in 29 of 32 roots (91%). It is concluded that myelography is indispensable for preoperative evaluation of cervical nerve root avulsion of birth palsy, because CT myelography is not sensitive to nerve root avulsion without a traumatic meningocele, and SEP cannot enable one to discriminate incomplete avulsion from intact roots.

Coaptation of the anterior rami of C-3 and C-4 to the upper trunk of the brachial plexus for cervical nerve root avulsion

No surgical procedure has been available to repair cervical nerve root avulsion inside the spinal canal. Results with peripheral neurotization of denervated muscles have been discouraging. The authors have performed bridge-graft coaptation in three patients with C-5 and C-6 nerve root avulsion. The components of the coaptation included the anterior primary rami of C-3 and C-4 as the donor material, the entire upper trunk as the recipient, and the sural nerve graft as the bridge. This procedure resulted in restoration of motor function in the biceps and shoulder-girdle muscles and produced improved sensation. Stimulation of the C-3 and C-4 nerve roots elicited electrical responses in the biceps and deltoid muscles that indicated nerve growth through the graft and the brachial plexus into these muscles. This reconstructive procedure is effective and should stimulate development of new approaches to treatment of cervical nerve root avulsion and proximal brachial plexopathy.

Restoration of elbow flexion and wrist extension in brachial plexus paralyses by means of free muscle transplantation innervated by intercostal nerve

Traumatic lesions of the brachial plexus with nerve root avulsion pose extremely complex therapeutic problems. Since 1965, the authors have performed neurotization of the musculocutaneous nerve by intercostal nerves in order to restore elbow flexion. The results of this operation are considerably poorer when the interval between the trauma and the neurotization exceeds 6 months. In these late cases, the authors have used, since 1978, a free muscle transfer reinnervated by a transposed intercostal nerve. 17 patients have been operated by means of this technique; 8 of the 11 patients with a follow-up exceeding one year recovered elbow flexion force evaluated to be M3 or more. Encouraged by these results, the authors have extended this procedure to restoration of wrist extension by free musculocutaneous transfer of the gracilis muscle innervated by intercostal nerves. 17 of the 29 patients operated have a follow-up of more than one year and 9 these cases have regained wrist extension with a score of M3 or more.

Regeneration after spinal nerve root injury

Spinal nerve root avulsion has been considered as a central nervous type of injury and therefore not repaired surgically in man. The possibility for axonal regeneration after root avulsion or root lesion has been investigated in laboratory animals by means of up to date neurophysiological, morphological and tracing techniques. It is shown that, after ventral root avulsion and implantation into the spinal cord, alpha and probably also gamma motoneurons are able to regenerate within the spinal cord for a considerable distance before entering the implanted root and reinnervate previously denervated skeletal muscles. The regenerated neurons were found to respond to afferent activity with excitatory or inhibitory responses, and the regenerated axons could conduct action potentials that elicited muscle twitch responses. After dorsal root injury in the adult animal, regeneration into the spinal cord does not occur. However, regeneration of primary sensory neurons into appropriate locations of the spinal cord can be demonstrated in immature animals.

Spinal Cord Stimulation in Deafferentation Pain

Spinal cord stimulation (SCS) was used in 49 cases to control resistant deafferentation pain resulting from causalgia, phantom limb, plexus and nerve root avulsion, postherpetic neuralgia, reflex sympathetic dystrophy and amputation. In all cases, one or two standard percutaneous leads were introduced into the epidural space and manipulated until the spinal segment at which external stimulation provoked paresthesic sensation in the painful area. Two weeks of external stimulation trial was used to determine the efficiency of the system. Pulse width of 0.1-0.2 ms, a rate of 80-120 cps and amplitude to low paresthesia threshold were programmed as electric parameters. In 36 out of the 49 tested cases showing a positive response to percutaneous SCS, the device was permanently implanted. After a mean follow-up of 5.5 years, 57% of patients had satisfactory pain relief (over 75%). Side effects were limited to dislodgement of the electrode in 1 case and wire extrusion in another, both requiring replacement of the stimulator.

Stretching of the brachial plexus in rabbits.

The brachial plexus of rabbits was stretched until mechanical failure. The level and site of rupture varied according to the direction of the stretching force. Upward and lateral traction of the forelimbs caused spinal nerve-root avulsions combined with nerve-trunk ruptures distal to the dorsal root ganglions. In such tractions the C5 nerves consistently exhibited postganglionic nerve-trunk rupture. The C6, C7, and C8 nerves had root avulsions. The T1 nerve was avulsed from the spinal cord in 7 cases out of 10; the other 3 cases had postganglionic nerve-trunk rupture. Downward traction of the forelimbs caused nerve avulsions from the scapulohumeral muscles innervated by the terminal branches of the brachial plexus and peripheral nerve ruptures in the course of the arm. The force producing trunk rupture of the C6 nerve was twice as great as that for root avulsion. The required stain was similar for nerve trunk rupture and root avulsion.

Neurotization via the Spinal Accessory Nerve in Complete Paralysis Due to Multiple Avulsion Injuries of the Brachial Plexus

The authors report their experience with 21 cases of neurotization via the spinal accessory nerve for multiple nerve root avulsion injuries of the brachial plexus associated with total paralysis of the upper limb. They performed microneuroanastomoses with interposed cable nerve grafts between the spinal accessory nerve taken in the supraclavicular fossa and the musculocutaneous nerve at its entrance into the biceps muscle. Surgical indications depend on the accurate diagnosis of spinal nerve root avulsion, especially C5. The anatomicosurgical basis of this technique is as precise as are the indications. As many as two-thirds of the patients with a neurotized musculocutaneous nerve can be expected to achieve strength of at least Grade 3 on late muscle testing. Nevertheless, these results are always inferior to those obtainable when grafting is performed with carefully selected unavulsed C5 or C6 spinal nerve root fibers in the intervertebral foramina. Therefore, neurotization via donor nerves extrinsic to the plexus should only be considered as a second-choice intervention.

Cervical myelography of nerve root avulsion injuries using water-soluble contrast media.

Eight cases of cervical nerve root avulsion injury are presented which were investigated by cervical myelography using a water-soluble contrast medium. The previous literature describes the appearances of this lesion using an oil-based agent and has resulted in emphasis being placed on looking for a traumatic meningocele rather than an abnormality of the roots themselves. The excellent definition of the nerve rootlets and axillary pouch that are obtained with a water-soluble contrast medium resulted in more root lesions per patient being detected than with an oil-based medium. There was complete correlation with the surgical findings at all but one root level explored. The appearances of root avulsion injuries and the advantages of using a water-soluble contrast medium are discussed.

腰神経根引き抜き損傷の一例

Traumatic lumbosacral nerve root avulsion has been recognized as extremely rare, compared with traction injury of cervical lesion. This seems to due chiefly to the structural characteristics of the mechanism of lumbar girdle. But recently, with the development of high speed transport, so called high momentum injury has been increasing.We report a case of a 58-year-old woman who sufferred from right 4th lumbar nerve root avulsion in the traffic accident.She had fractures of right pelvic ring and right transverse process of the 5th lumbar spine.Mechanism of this injury seemed to be left side bending of lumbar spine and fiexion-abduction displacement of right thigh.In treating a case of pelvic fractures associated with flaccid paralysis of lower leg, we must take into consideration an avulsion injury of the lumbar nerve root.

Imaging of Peripheral Nerve Lesions

The imaging of peripheral nerve lesions remains limited to the radiographic demonstration of secondary skeletal lesions in birth trauma, reflex sympathetic dystrophy, neuropathic arthropathy, leprosy, and congenital indifference to pain. Nerve root avulsions can be imaged directly and the newer imaging modalities now allow delineation of lesions that previously could not be studied using conventional radiography. The ability of ultrasound, CT, and MRI to differentiate soft tissue structures makes it possible, in many instances, to study the primary abnormality in trauma, nerve entrapment syndromes, and tumors. With fractures, the possibility of trauma to adjacent nerves can only be inferred on the radiographs, while the role that peripheral nerve injury plays remains controversial in other entities, such as amputation with replantation. Imaging of peripheral nerve lesions remains in its infancy. With further refinement in the signal-to-noise ratio made possible by advances in MRI technology, we may be optimistic about future imaging of peripheral nerve pathology.

Abnormal physiology of the dorsal horn as related to the deafferentation syndrome.

The spinal cord dorsal horn has been implicated in the generation of pain and dysesthesias following nerve and nerve root damage and/or avulsion, as well as following damage in adjacent spinal cord regions. Alterations in the functional properties of dorsal horn neurons occur after deafferentation and may underlie the occurrence of abnormal sensations referred to the denervated body part. Abnormal activity following deafferentation has also been noted at thalamic and cortical levels. Some of these post-denervation functional changes, determined anatomically and/or electrophysiologically, are reviewed as well as the results of behavioral studies of the deafferentation syndrome in the rat.

CT myelography in cervical nerve root avulsion.

Computed tomographic myelography (CTM) with metrizamide was performed in six patients to delineate the CTM appearance of avulsed cervical nerve roots. Twelve cervical nerve root avulsions were found and confirmed by cervical myelography and physical examination. The CTM findings in cervical nerve root avulsion closely matched those found myelographically: outpouchings of metrizamide extending ventrolaterally from the thecal sac into the neural foramen in an expanding or "mushroom-like" manner and separated from the thecal sac proximally by a 1-2 mm thick dural plane. This CTM appearance differs from that seen in such normal variants as dilated nerve root sleeves or root diverticula. We conclude that CTM is as sensitive as myelography. In addition, it can provide useful information regarding bony fragments or contiguous soft tissue injury.

Neuropharmacology of the Dorsal Root Entry Zone

The finding of a number of peptides in the central nervous system and the discovery of the endogenous opiates represent major recent advances in the understanding of neural transmission. A number of these neuropeptides are found in the dorsal root entry zone and may play a role in pain. An analysis of changes in distribution of substance P, methionine-enkephalin, and somatostatin after simulated nerve root avulsion injury suggested a possible mechanism for deafferentation pain. A review of the localizations and actions of these peptides in the dorsal root entry zone is included.

Investigation of brachial plexus injuries by intraoperative cortical somatosensory evoked potentials

With the intention of estimating the extent and site of damage in brachial plexus injuries which involve close to the root outlet and also the distal portion, cortical somatosensory evoked potentials (SEP) were recorded in 21 patients by directly stimulating the exposed brachial plexus. In 38 avulsed nerve roots which showed positive sensory action potentials (SNAP)/nerve action potentials (NAP) in their peripheral part, 15 roots (nine patients) were apparently in continuity and confirmed as root avulsion injury by the absence of cortical SEP. However, 11 roots (ten patients) which showed neither SNAP nor SEP would suggest either extensive lesions involving root and more distal segment or a combination of root avulsion and postganglionic injury. Fourteen patients who showed a positive Tinel's sign had at least one root with a postganglionic type lesion, but cortical SEP evoked by stimulation of the most proximal root zone sometimes revealed a reduced amplitude and prolonged latency. This would indicate the retrograde extension of damage. To confirm the extent and degree of the nerve lesions in brachial plexus injuries, an intraoperative SEP and NAP recording is very useful, practical, and also indispensable.

Pain in avulsion lesions of the brachial plexus

Traction lesions of the brachial plexus are becoming more frequent. Many of the lesions involve avulsion of nerve roots from the spinal cord. This very often results in severe pain which is associated with deafferentation. Although reference to this pain and the difficulty in its management has been made is several reports in the literature, there has been no long-term study of the natural history of this pain and the effects of various attempts to mitigate it. This series reports on a long-term follow-up of 275 patients of which 108 had evidence of avulsion lesions. Of these 108, 98 suffered significant pain. There is a remarkably constant description of the pain and the various activities that may affect it. Drugs are of very limited use and the most valuable method of treatment found in this series was transcutaneous electrical stimulation — although, only one-third responded dramatically to this treatment. The single most effective manoeuvre that reduces pain is absorption by the patient in work. There remains a significant number of young men with severe pain who may expect to suffer such pain indefinitely. There is urgent need for new methods to be developed to control this pain.

Pain relief after dorsal root entry zone lesions.

Pain is an early symptom following avulsion of the brachial plexus in 70% of patients, but only 20% develop intractable disabling pain requiring surgical Intervention. In the past neurosurgical treatment has consisted of rhizotomy, cordotomy, dorsal column stimulation and stereotactic mesencephalotomy all of which have been largely unsuccessful 1, 2. Recently 18 patients with intractable pain from brachial plexus avulsion lesions were treated with a new surgical technique using radiofrequency coagulation of the dorsal root entry zone (DREZ) of the cervical cord in the region of the avulsed nerve root. Since the initial clinical results in the brachial plexus avulsion patients were encouraging, we have applied the treatment to three additional patients with intractable pain from other causes. These include one man with a gunshot injury to the brachial plexus, a woman suffering from a gunshot wound to the spine with involvement of the spinal word and a third man with intractable chronic pain due to a pelvic tumour.KeywordsPain ReliefBrachial PlexusGunshot WoundIntractable PainAvulsion InjuryThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Avulsion of nerve rootlets with the Cuatico needle during Pantopaque removal after myelography

Three cases of histologically proven nerve root avulsion during Pantopaque removal with a Cuatico needle are described. While use of such multihole needles poses some risk to patients, we feel the advantages outweigh the disadvantages, particularly when a large volume of Pantopaque has to be removed. To minimize the possibility of nerve root avulsion, we recommend minimal manipulation of the needle and cannula during Pantopaque removal, use of gentle suction, termination of suction and injection of cerebrospinal fluid if pain occurs, and slow withdrawal of the cannula and stylet.

LUMBOSACRAL NERVE ROOT AVULSION

The 14th myelographically demonstrated case of lumbosacral nerve root avulsion is presented with a summary of the previously reported cases. In most cases lumbosacral nerve root avulsion is associated with pelvic fractures and sacroiliac dislocation, which cause a stretching force to be applied to the nerves of the lumbar and sacral plexuses, and in turn to the nerve roots intradurally. This force causes nerve root avulsion in the intradural course of the nerve root. The myelographic defect is a pseudomeningocele or diverticulum-like outpouching created by the tearing of the arachnoid covering of the nerve roots. Myelography clearly indicates nerve root avulsion and surgical exploration is not indicated.

Pantopaque-myelographic findings in brachial plexus root avulsion (author's transl)

The myelograms of 7 patients with traction injury of the brachial plexus are compared with the operation findings. It appears that not only the roentgenological sign of the "traumatic meningocele" but also other myelographic abnormalities are to be considered as indications of a nerve root lesion. These changes are demonstrated. The myelogram of a 6-months-old child showing a nerve root avulsion due to birth trauma is represented. Myelographic examination of each patient with posttraumatic brachial palsy should be performed as soon as possible. A sufficient myelographic diagnosis of the nerve root lesion can be achieved only in considering also the less impressive radiological signs.