Selective posterior spinal nerve root block is currently an effective surgical procedure for the treatment of spastic cerebral palsy. Spastic cerebral palsy is usually thought to be due to the weakened inhibitory effect on gamma motor neurons after damage to the cerebral cortex and downward inhibitory conduction pathways in the brain, resulting in increased excitability of gamma motor fibers, causing increased sensitivity of the muscular spindle and producing abnormal discharges, which act on alpha motor neurons through the class Ia afferent fibers of the muscular spindle, resulting in spastic contraction of limb muscles.
Based on the above pathophysiological mechanism of spasticity, the spasticity of the limb is released or relieved by selectively blocking class Ia afferent fibers in the posterior root, preserving other sensory nerve fibers, and blocking the gamma loop in the spinal cord reflex. To relieve spasticity in the upper extremity, class Ia afferent fibers in the posterior roots of the spinal nerves in the cervical spinal cord (C5 to T1) are selectively blocked, and in the lower extremity, class Ia afferent fibers in the posterior roots of the spinal nerves in the lumbosacral segment (L2 to S1) are selectively blocked.
Compositionally, the posterior roots contain a variety of nerve fibers, which can be classified according to their function as.
① deep and superficial cutaneous sensory fibers.
(ii) muscle and tendon sensory fibers, and
(3) visceral sensory fibers.
According to the morphology and physiological characteristics of the fibers, they can be divided into.
① Class A fibers, thick myelinated fibers, with a diameter of about 3-20 μm and fast conduction speed;
(ii) Class B fibers, myelinated, about 3 μm in diameter, with a slower conduction speed than Class A fibers;
(iii) Class C fibers, unmyelinated fibers, have the slowest conduction speed.
According to the condition of myelin sheaths, they can be classified as
① myelinated fibers.
②unmyelinated fibers. Unlike the posterior roots, the anterior roots have a more homogeneous fiber composition, which are all myelinated motor fibers. Depending on their functions, they can be broadly divided into α motor nerve fibers, which innervate the extra-saccadic muscles, and γ motor fibers, which innervate the intersaccadic muscles.
Recent studies over the last decade have shown that the anterior root contains a small number of unmyelinated sensory fibers, and the function of these sensory fibers is generally considered to be somatosensory afferent fibers. Radiofrequency selective posterior spinal nerve root block has reached a world advanced level for the treatment of spastic cerebral palsy. Under general anesthesia, the posterior roots of the spinal nerve are viewed directly from the lateral posterior part of the spinal cord and are naturally divided into several bundles, which are electrically stimulated to induce spasticity in the limbs. In order to establish a new dynamic balance around the joint, correct non-fixed deformities, prevent the occurrence or aggravation of fixed deformities, and improve the flexibility of sitting, climbing, kneeling and other movements of the limb and the stability of standing and walking.
Contracture and joint deformity problems
The activity of the muscular, skeletal system is influenced by the state of the connective tissues (tendons, ligaments, fascia, joint capsule) with which it is closely related. The fibrous composition of connective tissue is made up of collagen fibers, reticular fibers and elastic fibers. When the tissue is damaged or there are deposits of fibrin between the fibers of the connective tissue, these components are often intertwined in a physiological state maintained by new growth and destruction.
Tissue collagen fibers of tendons and ligaments are dense connective tissue regularly arranged in the direction of the long axis and loose connective tissue rich in mobility within a certain range. The ligaments and joint capsule in joints that have contracted are mainly collagen fibers arranged in a mesh-like multi-layered pile, with fewer gaps between fibers and poor mobility, and the fibers themselves are less elastic, becoming a very tough dense connective tissue with no mobility. If the tissue spasm lasts too long, there will be cellular infiltration of soft tissue, fibrin exudation, and connective tissue proliferation, gradually forming dense connective tissue into contracture.
The main prevention method is to move the joints within the range of motion with gentle manipulation, which can promote local blood circulation and maintain the appropriate tension of tendons, ligaments, fascia and joint capsule. If improper massage techniques are forced on the already severely contracted tissues, it will cause local edema and bleeding and aggravate the contracture. In the actual treatment process, due to some informal personnel do not understand the basic medical knowledge, the use of rough massage techniques, resulting in serious damage to the tendons or even tendon rupture, so that the original function of the muscle loss of function.
Maintaining normal joint range of motion is more important, easier and practical than treating contractures that have already occurred and preventing them. Healthy people move their joints unconsciously during the movements of daily life, maintaining a normal range of joint motion without contracture. In contrast, people with cerebral palsy are unable to move flexibly and autonomously because of the presence of spasticity, they are unable to overcome poor posture and limb position by themselves, their joint range of motion is limited, and they do not perform functional training, or even if they do, contractures may occur. The goal of maintaining normal joint range of motion is directly to prevent contractures. The methods can be broadly divided into three categories, passive exercise, voluntary mediated exercise and active exercise. Amount of training: Each joint is effectively moved within the normal range of motion, 3 times per repetition, once a day in the morning and once in the evening. The specific method is described in the section on home functional training methods.
Surgical problems
Surgical treatment should be considered for joints that have contractures or deformities, and should be done very carefully. The cases selected for surgical treatment are characterized by the presence of increased muscle tone (spasticity), with an average of 3 or more levels according to the Ashworth 5 level method.
Upper extremity: with deformities of cerebral palsy hand, wrist flexion, forearm rotation forward, elbow flexion, etc. Individual cases had shoulder deformity.
Lower extremities: ptosis, clubfoot, clubfoot, flatfoot, knee flexion contracture, hip flexion contracture, adductor contracture and other deformities, and movement disorders in the corresponding areas. In daily life, the affected limb (hand) is divided into complete users, auxiliary users, and non-users. Those who use upper limb soft tissue surgery alone.
According to the condition, the following surgeries are performed, such as the lowering of the starting point of the forearm flexor group, the ulnar carpal flexor muscle or the rotator anterior round muscle instead of the radial carpal long and short extensors, the long palmar muscle instead of the long thumb extensor or long thumb extensor, the superficial and deep flexor tendons of the fingers, the extension of the long thumb extensor tendon, the release of the interosseous membrane of the forearm, and the partial severance of the axillary nerve or the musculocutaneous nerve in individual cases. Simple soft tissue surgery of the lower extremity includes lengthening of the Achilles tendon, lengthening of the posterior tibial muscle, external displacement of the anterior tibial muscle, anterior displacement of the posterior tibial muscle, lengthening or superior displacement of the country rope muscle, severance of the adductor muscle, and superior displacement of the stop of the iliopsoas muscle. Common bony procedures include fusion of the carpal joint and external fixation of the subtalar joint.
The results of the follow up were in all cases with varying degrees of therapeutic effect. In terms of deformity improvement, muscle balance, spasticity release, limb function and manual dexterity, the deformity improvement and muscle balance were superior in those who underwent upper and lower limb soft tissue surgery alone. Selective posterior spinal nerve root block was found to reduce spasticity and improve limb dexterity. Selective posterior spinal nerve root block supplemented soft tissue surgery with the most satisfactory results. Limb spasticity is predominant in infancy or early in the course of the disease when spasticity leads to dysfunction, with soft tissue contractures gradually developing with age.
For children with severe spasticity or those with contracture starting at a younger age, soft tissue surgery performed in a spastic state will result in easy recurrence of the deformity, difficult balance of muscle strength or deformity opposite to the original deformity, and poor limb flexibility. In cases where both spasticity and fixed deformity are severe, the experience is to perform selective posterior spinal nerve root block in phase I to relieve spasticity and soft tissue surgery or bone surgery in phase II (bone surgery is usually performed after 12 years of age). In this way, the advantages of each type of surgery are exploited, and their respective shortcomings are compensated for, so that the patient receives meaningful treatment in terms of deformity improvement, muscle balance, spasticity relief, limb function, and manual dexterity.
There is a basic concept worth noting in the treatment process, that is, the direct effect of surgery is only to solve the basic problems of spasticity, muscle strength imbalance and joint deformity, and to create conditions for functional recovery. Especially in the upper extremity, the patient may often avoid the use of the severely affected hand before surgery, which also has a significant impact on the prognosis. It should be explained to the family and the patient that using the affected limb as much as possible so that it can function normally is helpful to improve the function after surgery. Functional training is an important part of the postoperative period and an important guarantee of the efficacy, and it can be said that surgery and training are indispensable without one another. It includes training of basic movements, muscle strength, life movements, coordination and flexibility.
Problems of involuntary movements and ataxia
The lesions are located in the basal ganglia and extrapyramidal system of the brain, and the patient shows continuous, irregular and purposeless movements, i.e. tardive dyskinesia. The symptoms are exacerbated when the patient is easily stimulated or consciously inhibits such movements, and disappear during sleep. In ataxia, the lesions are in the cerebellum, mainly involuntary movements of the trunk or walking and poor balance.
Hand-foot tardive dyskinesia and ataxia are considered as contraindications to all the above-mentioned surgeries because surgery does not reduce the abnormal activity of patients with hand-foot tardive dyskinesia and ataxia, especially because it is impossible to treat hand and upper limb dysfunction effectively. Treatment of such patients should be based on active, self-directed normal movement training to overcome involuntary movements through conscious and active normal movement training.
Special attention should be paid to the training of such patients, which should be carried out in a relatively relaxed and pleasant environment, and the training process should not cause mental tension or make the patient feel repressed, such as scolding the patient and feeling pain when moving passively. It is best to match the patient’s daily habits and hobbies with some relaxing, elegant and slow rhythm music, without loud volume or noise.
Hyperbaric oxygen therapy problems
Neonatal hypoxia and ischemic encephalopathy are the main causes of early neonatal death and impaired mental development. The use of hyperbaric oxygen therapy in the neonatal period at home and abroad has achieved encouraging results. Its principle: by increasing the partial pressure of blood oxygen, cerebral blood vessels are constricted, cerebral blood volume is reduced, cerebral edema is reduced, and intracranial pressure is lowered, interrupting the vicious cycle between cerebral hypoxia-cerebral edema-rising intracranial pressure. Although cerebral blood flow is reduced, the oxygen supply to brain tissue is instead increased due to increased blood oxygen content and enhanced oxygen diffusion capacity, thus improving and correcting the hypoxic state of brain tissue. The efficacy is related to the age at which treatment is started, with early treatment having good results. The optimal time of neonatal period and infancy (within 1 year of age), when the neurological system is plastic, should be used for treatment; the effect is not obvious after 1 year of age.
Problems with brace use
It can be used as an adjunct to treatment to control involuntary movements such as tardive dyskinesia, improve posture and prevent deformities, but it has little effect on deformities that have already occurred, especially those with heavy soft tissue contractures or bony deformities that have developed. It is important to note that braces can affect skeletal development in young children, so extra care should be taken when fitting younger children with cerebral palsy. Inappropriate use of braces can interfere with normal muscle strength, rendering some muscles inoperative and causing them to become disuse atrophy. In young children, the original size of the brace will need to be replaced as the limb grows. The fitting of the brace should vary from person to person, and the amorphous brace can be suitable for all types of cerebral palsy patients.
Medication issues
To date, there are no convincing medications to effectively treat the brain lesions of cerebral palsy. Many medications suggest that the treatment of cerebral palsy mainly refers to the improvement of cerebral circulation through medication in the early stages of cerebral palsy onset, when the brain is not yet mature. In fact, when cerebral palsy is detected and diagnosed, the brain lesion has long been immutable. At this point, medication will not help the brain lesions. Many parents do not understand this and cause great waste financially and materially. Drugs can only be used to control the symptoms of tardive dyskinesia or limb tonicity in tardive dyskinesia and tonic cerebral palsy, but the results are not satisfactory. 30 years ago, phenol or alcohol blocks were used to inject the nerve-muscle junction with the aim of reducing spasticity, but there was no long-lasting effect, and most of the symptoms recurred six months after the injection, and made further treatment difficult.