Protrusion of discs of the lumbar spine: what is it, diagnosis, treatment and spinal surgery

Spinal osteochondrosis is the main provocateur of the development of degenerative-dystrophic changes in the lumbar intervertebral discs with the formation of a hernia. Due to advanced osteochondrosis, the lumbar disc (LD) begins to lose water and experience a deficiency in valuable nutritional components, as a result of which it gradually becomes deformed. The initial degree of such deformation is protrusion.

But, despite the still minor changes in the intervertebral L-disc, the early stage (pre-hernia) is quite painful for many patients. The pain can become severe and prolonged, and is difficult to respond to conservative treatment, including painkillers. During this initial period, along with severe pain, the biomechanics of the lower spine often suffers seriously.

Protrusion of the disc and pressure on the nerve root.

Yes, many people with small disc bulges can also experience real physical pain, sometimes even more than some patients with large true hernias. The issue of operations is no less relevant for people who have been diagnosed with lumbar disc protrusion. Therefore, we will characterize this diagnosis and talk about treatment methods, in particular about the possibilities of modern neurosurgery for lumbar protrusions.

What is disc protrusion

Protrusion is a complication of the last stage of osteochondrosis, which is characterized by a slight bulging of the contour of the intervertebral disc beyond the physiological boundaries without rupture of the fibrous ring. To better understand what we are talking about, read the information below, which includes information on the structure and function of the discs of the lumbar spine.

• The lumbar region consists of 5 (less often 6) large vertebrae. In the spaces between each pair of adjacent vertebrae there are elastic fibrocartilaginous pads, medically called intervertebral discs. In the alphanumeric version, each segment where the disk is located is represented by the following names: L1-L2, L2-L3, L3-L4, L4-L5.

  Healthy and osteochondrosis-affected spine on CT scan.

• The role of such intervertebral spacers is to connect 5 bone bodies with each other, to provide shock absorption, mobility, stability and flexibility of the department during physical activity. By the way, the fifth vertebra is also connected to the sacrum through a disc, and the L5-S1 area is one of the most vulnerable zones in terms of the development of protrusion. Level L4-L5 has the same high predisposition to pathology. In the general structure, lumbar and lumbosacral protrusions and hernias account for as much as 90% in the frequency of lesions in L5-S1 and L4-L5.

• What are lumbar discs? They consist of the annulus fibrosus and the nucleus pulposus. The structure of the annulus fibrosus is formed by ring-shaped collagen fibers that surround the disc along the periphery. Inside the ring is the nucleus pulposus - a cartilaginous semi-liquid mass of jelly-like consistency, having a spherical shape. The discs are nourished through the circulatory network of the vertebrae that are associated with them and the endplate.

• Under the influence of an unfavorable factor in the part of the lumbar region where it has the greatest impact, a disruption of blood circulation and nutrient synthesis occurs. For example, systematic physical overload or physical inactivity, high body weight, systemic pathologies in the body, back injuries, etc. predispose to such an outcome. Against the background of a lack of blood supply and metabolism, degenerative-dystrophic processes are triggered locally, or, as they say, osteochondrosis occurs.

• In the absence of adequate treatment for osteochondrosis, degeneration of the peridiscal structures gradually progresses, affecting the marginal plates, which become sclerotic. The production of nutritional components and their delivery to the “destination” (into the disk) is reduced. Due to a pathological lack of important elements, the intervertebral cartilage eventually experiences depletion of fluid resources and begins to deteriorate. Protrusion occurs.

The formation of lumbar protrusion is accompanied by thinning, delamination, and microtears of the fibers of the inner layers of the fibrous ring of the disc in a certain area. The nucleus moves to this area of ​​greatest thinning, putting pressure on it, which causes the disc to bulge into the spinal canal. At the same time, the integrity of the external structures of the ring remains intact at the protrusion stage. This is the initial stage of hernia formation, but not yet the hernia itself, although it is classified as stage 1 of intervertebral hernia.

Complications

Timely initiation of treatment for L4–L5 intervertebral hernia is the key to its success and elimination of the risk of complications. If you do not intervene or ignore the doctor’s recommendations, the disease can lead to:

• spinal canal stenosis;
• paresis and paralysis of the lower extremities;
• loss of control over the process of urination;
• persistent impotence;
• infertility;
• disability.

Therefore, we recommend not to delay contacting a doctor. In the early stages of development, L4–L5 hernia responds well to conservative therapy and does not lead to the development of undesirable consequences.

5 1 vote

Article rating

Stages, types of disc protrusion in the lower back

There is a classification of lumbar protrusions according to stages of development, which makes it possible to determine the severity of the clinical process.

1. The first stage (mild) is characterized by the smallest, barely noticeable protrusion of the disc, which not every specialist can detect, even with MRI images. Dimensions – 0.1-1 mm.
2. The second stage (moderate) - the bulge increases, making it easier to diagnose using special imaging tools. The size of protrusion in stage 2 is 1-3 mm.
3. The third stage (severe) - at this stage the displacement is already quite large, clearly visualized behind the contours of the vertebrae. Instrumental examination shows a formation of 3-6 mm, but still no signs of rupture of the outer part of the fibrous ring.

The last stage (3rd stage) is borderline with extrusion. And from this it follows that at any moment, against the background of strong sagging of the pulpous mass, the fragile fibrous ring may not be able to withstand it and finally burst. Then part of the nucleus will crawl out through the formed hole, which means a hernia will appear, in the true sense of the word from a medical point of view. However, we will not go beyond the scope of the article; let’s return to lumbar protrusion. Let us briefly consider its varieties depending on the direction and position of the resulting bulge.

Variety	Characteristic
Dorsal	It protrudes from the vertebrae posteriorly, in the direction opposite to the spinal canal. This form is rare and clinically the calmest.
Lateral	Protrudes from the right or left side of the vertebra, in the projection of the foraminal opening. Common type. Often comes into contact with the nerve processes emerging from the intervertebral foramen.
Median	Prolapse “looks” strictly at the center of the spinal canal, where the nerve bundle of the spinal cord – the cauda equina – is concentrated. Worst location ever.
Circular	Uniform or uneven defect along the entire circumference of the disc. This is another dangerous form, and it is also the most common (80%).

Pain and symptoms of protrusions

Lumbar protrusions at the initial and middle stages are often asymptomatic or mild. As a rule, in the lumbar region, pain and limited mobility begin to worry with the onset and progression of stage 3, when the bulging part of the disc has reached 3 mm or more. The first sign of an unfortunate deformity is pain in the lower back, which is accompanied by stiffness of the spine in the lower part. Next, we will present a complete list of classic manifestations of lumbar and lumbosacral protrusions and point out their specificity.

• Pain syndrome.
  The appearance of pain indicates the involvement of spinal nerves in the pathogenesis. With protrusion, it predominantly has an intermittent, dull, aching character. Not without exceptions, of course. Painful sensations can also manifest themselves in the form of a burning sensation or paroxysmal shooting, and can be quite persistent. Painful phenomena often intensify when trying to change position, during physical activity, during or after staying in a monotonous position for a long time (for example, when sitting for a long time). Pain may radiate to one of the lower extremities; more unpleasant discomfort is noted in the thigh and calf muscle.
• Mobility block.
  A decrease in motor potential is determined in the lower back. The patient complains of difficulties when trying to bend forward/backward or turn the body to the side. Many people are prevented from performing one or another type of movement of the lower back by emerging or increasing pain. Sometimes it is also problematic to move from a calm state to an active one precisely because of constriction and stiffness at the level of the lesion.
• Sensory disturbances.
  Clinicians scientifically call this type of disorder paresthesia. They are characterized by unnatural sensations in the problem area in the form of tingling, numbness, and crawling. It is worth noting that sensory disturbances can occur in the skin, lumbar muscles and/or in the leg, perineum and thighs. For many people, they begin to be felt in the area of ​​the fingers, feet, and back of the lower leg. After increasing physical activity, paresthesia often resolves on its own.
• Impaired muscle tone.
  This phenomenon is characterized mostly by weakness and rapid fatigue of the muscular system of the legs. In the back, at the time of exacerbation of protrusion, the muscles, on the contrary, are often in a state of hypertonicity and spasm. As the disease progresses, if there is no proper treatment, both described conditions are fraught with severe muscle atrophy, up to the inability to stand and move confidently.
• Dysfunction of the pelvic organs.
  Pathological deviations in the functions of the bladder, intestines, and reproductive organs are an extremely unsatisfactory complication of an advanced state of protrusion, indicating the presence of cauda equina syndrome. The main symptoms are urinary and fecal incontinence, impotence, problems with conception and pregnancy. Such a syndrome is a compelling argument for urgently prescribing surgery, since untimely assistance threatens not only the irreversibility of pathologies, but also paralysis of a person. Fortunately, at the stages of protrusion, cauda equina syndrome is relatively rare.

The intensity of pain and other neurological signs, the combination and number of symptoms primarily depend on the location, volume of the lesion, the degree of inflammation and swelling of the nerve tissue around the disc.

Prevention

The main problem of prevention for posterior disc protrusions is maintaining proper muscle tone and posture. This may involve playing sports, therapeutic exercises or yoga.

This is especially important if the patient has a curvature of the spine (scoliosis). It is advisable to avoid prolonged positions with the torso tilted forward and the head tilted forward, since it is these loads that primarily provoke the formation of posterior disc protrusions.

If you experience even minimal complaints from the back, lower back or neck, you should definitely consult a doctor who specializes in spine diseases. The sooner protrusion is diagnosed and the sooner treatment is started, the more effective and quick the treatment result will be.

Examination methods

During the first visit, the neurologist conducts an initial examination of the patient, which includes a complete history taking and special tests to assess the patient’s neurological status. A qualified specialist will be able to suspect lumbar disc protrusion based on initial monitoring of the problem. We emphasize that it is impossible to just suspect, approve and prescribe treatment without conducting instrumental diagnostics. Similar symptoms and signs of neurological deficit are typical of many central nervous system pathologies.

In order to confirm or reject this diagnosis, the neurologist refers the patient to study this department using magnetic resonance imaging. X-ray can also be used, but only as a preliminary MRI examination, since it is completely devoid of the ability to visualize soft tissues. And soft tissues are the disc itself, nerve and vascular formations, the spinal cord, and muscle-ligamentous structures.

Protrusion on MRI.

In the topic of “making a diagnosis,” it is impossible not to inform patients that taking an anamnesis, neurological tests and radiography are also of great importance. Yes, these are auxiliary methods, but they allow a specialist to:

• find out about the nature, strength, time of appearance, frequency of recurrence of disturbing ailments before a person goes to a medical institution;
• assess muscle strength, coordination, motor-support potential and identify the relationship between the increase in pain and a particular movement;
• understand what the patient’s level of physical data was before the onset of the disease and what it is now;
• identify violations of posture, measure the range of motion of the spine in all physiological directions;
• carefully examine reflexes and tactile sensitivity;
• determine the presence, size, number of osteophytes in the examined area of ​​the ridge, shifts of the vertebrae relative to each other, the size of the intervertebral space, bone density;
• study the history of a person’s illnesses, lifestyle, professional sphere, record weight and height, take into account age, which, like everything else, plays an important role in identifying the etiology of degenerative spinal disease and in determining treatment tactics.

The process of dislocation of the nucleus pulposus, metamorphosis in the tissues of the fibrous ring, the accuracy of the location and direction of protrusion, nerve entrapment and the condition of the spinal cord can be determined purely on MRI images.

MRI allows you to collect comprehensive information down to the smallest details about the condition of all disks and other structural components at each software level. Based on cross-sectional MRI images of the area under study in the sagittal plane, even the smallest protrusions, which are less than 2 mm, are determined. After the doctor confirms the diagnosis, treatment that is adequate in the particular case and will be effective is prescribed.

Reasons for education

The predominance of the rate of destruction of intervertebral discs over their restoration occurs as a result of age-related changes or the regular action of increased loads on them. In such situations, osteochondrosis develops, which is the main prerequisite for further thinning of the cartilage tissue and the formation of L4-L5 protrusion.

Due to the fact that during pregnancy the load on a woman’s body doubles, it is very important to put the spine in order. Our clinic has developed and prepared a special program of comprehensive examination and treatment for pregnant women and those planning pregnancy.

Thus, the main reasons for its development are considered:

• sedentary lifestyle - leads to prolonged static loads on the spinal column, decreased tone of the back muscles and loss of adequate support for the spine;
• excess weight - every extra kilogram increases the load on the spine and especially its intervertebral discs;
• poor posture – lead to improper distribution of the load on the spine when walking, standing, sitting, and physical work;
• heavy physical labor, lifting heavy objects - increases the load on the discs, leading to their faster wear.

Endocrine disorders, in particular diabetes mellitus and its complications, also indirectly contribute to the development of osteochondrosis, and then protrusion, since they lead to impaired blood supply to the discs.

Treatment methods and their effectiveness

For lumbar protrusions, conservative and surgical therapy is recommended. In some cases, a conservative approach helps to effectively combat exacerbations and relapses of pathology. The main purpose of non-invasive tactics:

• relieve pain and inflammation, create favorable conditions for nerve roots;
• improve blood circulation, metabolism, nutrition delivery to a weakened area;
• prevent the progression of disc destruction and ensure the prevention of recurrence of protrusion symptoms;
• increase mobility of the diseased area;
• prevent the development of muscle atrophy (back, lower extremities);
• to prevent as much as possible from degenerating the protrusion into a true hernia (unfortunately, in practice, sooner or later this outcome of the disease usually occurs in most patients).

For conservative treatment to truly be beneficial, it must comprehensively and competently take into account all the criteria of the underlying pathology, concomitant diseases and the individual characteristics of the patient’s body. Therefore, it is ideal that only a highly competent doctor observing the patient can plan it. So, what is included in the basic range of non-invasive treatment and are its methods effective?

1. The use of medications is the effect of drugs on a disease. Among the medications used are: non-steroidal anti-inflammatory drugs (if necessary in the acute phase) - Ketorol, Ibuprofen, Diclofenac; stimulators of metabolism and regeneration of cartilage tissue - Chondromix, Rumolon; vitamins and dietary supplements based on B vitamins and calcium. All medications act symptomatically and prophylactically. For minor protrusions, chondroprotectors and mineral-vitamin formulations in combination with other mandatory treatment tactics still work well, preventing the destructive pathogenesis from progressing. And in isolated cases, they can completely restore the disc if it is deformed by no more than 1 mm. Formations larger than 1 mm are only prevented from progression by these drugs, but not for everyone and not always. Painkillers of any group have no effect on reducing the volume of protrusion; they can only “extinguish” painful symptoms.

2. Physical therapy is the leading type of conservative recovery for the patient. Tactics involve the daily use of moderately gentle but effective physical training techniques. Exercise therapy relieves the pathological area from excessive tension, locally and generally increases the endurance and plasticity of the musculoskeletal system, produces a tonic effect, and improves the synthesis of the main metabolites of the disc. In addition, due to proper gymnastics, the vertebrae and joints are straightened, thereby increasing the intervertebral space and freeing the nerve roots from the clamp. The effectiveness of the exercise therapy method has been proven. Of course, a complete cure will not take place, such is the nature of the pathology, but keeping protrusion under control is quite possible. However, the value of the exercises will be negated by the unauthorized use of exercises, the recommendations of which the patient received not from the first person (his own specialist), but from second parties (friends, consultants from thematic Internet sites, etc.).

3. Physiotherapeutic procedures – stabilization of well-being with an optimally selected set of physical sessions. A selection of physiotherapy may consist of several procedures in one treatment and rehabilitation program. For example, from electrophoresis, shock wave treatment, laser therapy, magnetic therapy, balneo- and mud therapy, etc. Physiotherapy can significantly improve the patient’s well-being and lead to a long-term stop in the further development of pathology. Its effectiveness is especially noted for protrusions of mild and moderate severity, not complicated by neurological deficit. Unfortunately, a lumbosacral lesion of this form cannot be regressed and eliminated forever.

4. Massage procedures are auxiliary treatment with special non-traumatic massage techniques. Massage locally stimulates lymphatic drainage, blood circulation, and metabolic processes. Thanks to its action, muscle tone, reflexes and sensitivity are corrected, locomotor and support strength of the lumbosacral segments are improved. The level of effectiveness is similar to physiotherapy. Massage for certain types of displacements may be completely contraindicated. Therefore, it is forbidden to contact him without the consent of the treating doctor. If the doctor approves such medical care for your diagnosis, it should be done exclusively in a medical facility with the best specialized massage therapist. Otherwise, you run the risk of serious consequences. And this is instability of the spine, an increase in the degree of disc prolapse, critical infringement and death of nerves, the development of prolapses at other levels, etc.

Methods of physiotherapy, exercise therapy, and massage can be put into practice only in the absence of signs of inflammation and pain, that is, without relapses. Initially, during the acute period, the patient is treated with medications, wearing an orthopedic bandage and ensuring maximum rest for the lower back. Only after the acute phase has been completely suppressed are the sound methods used.

Clinical experience shows that 5%-10% of patients with protrusions require surgical treatment. As a rule, minimally invasive puncture technologies of neurosurgery from the nucleoplasty profile are used. Further about the indications, features and effectiveness of minimally invasive procedures.

Medial hernia (also called Schmorl's hernia)

Shows no signs.

There are also symptoms common to all types:

• increased pain during physical activity, eating, defecation;
• relief of pain in a standing position;
• autonomic disorders (sweating increases, legs swell, skin becomes dry);
• unbearable pain if you try to lift your straight leg while lying on your back, and the disappearance of pain if you bend the raised leg at the knee.

Operation for protrusion

Let us recall that protrusion is the initial form of herniation, when the anatomical integrity of the outer sphere of the fibrous ring is preserved, due to which the nucleus pulposus is still located in the disc. Only such a picture of the disease allows the use of puncture methods of plastic disc surgery. It is advisable to recommend nucleoplasty to a person with a protrusion of the lumbar/lumbosacral location only under the following circumstances:

• ineffectiveness of non-surgical treatment for 3-6 weeks;
• frequent exacerbations of painful symptoms;
• dysfunction of the nerves of the equine ganglion;
• chronic reflex and radicular syndrome;
• rapidly progressing dynamics of protrusion development.

Puncture nucleoplasty is aimed at reducing the pressure inside the intervertebral disc, which facilitates the return of the latter to its normal shape. The effect of reducing intradiscal pressure and retracting deformation is ensured by direct impact on the core (with the goal of its partial destruction) by a certain physical factor:

• cold plasma (cold plasma plastic);
• laser (laser vaporization);
• electromagnetic waves (radiofrequency ablation);
• a pressure jet of isotonic liquid (outdated tactics, hydroplasty).

At their core, all methods of influence “work” and are carried out according to the same principle. They are also approximately equal in effectiveness - the success rate of the procedures is approximately 80%. Access to the intervertebral disc is carried out from the back percutaneously (through a puncture puncture). Anesthesia is used mainly of a local type, but in some situations general anesthesia or epidural anesthesia is not excluded. The intervention is carried out on an empty stomach, before which the patient is given a cleansing enema. The procedure is carried out in the department of minimally invasive neurosurgery, equipped with an intraoperative X-ray machine. Session duration is 15-30 minutes. Let's consider all stages of nucleoplasty.

1. The patient is placed on the operating table. The classic position is on your side, with your legs tucked towards your stomach.
2. The skin of the lumbar region is widely treated with antiseptics. Anesthesia is performed.
3. Under X-ray control, in a safe interval, the surgeon makes a puncture (2-5 mm) with a puncture needle inserted into the disc at the required distance. Usually to the center of the core.
4. An electrode is installed into the working cannula of the needle, through which the “destruction agent” of the gelatinous substance will be supplied.
5. By rotating and translational movements of the electrode, emitting, for example, pulses of laser radiation or a flow of low-temperature plasma, the jelly-like component in the disk is partially evaporated.
6. The denucleation performed ensures inverse retraction of the pulpous mass that has shifted to the periphery of the ring during the course of the disease. The configuration of the lumbar disc is restored, and the pinched nerve root is eliminated.
7. At the end of the operation, thin working instruments are removed, and an antiseptic patch is applied to the puncture. Usually such a tiny wound does not require stitches.

During the procedure.

If the protrusion is not confirmed by MRI, and a rupture of the fibrous part of the intervertebral lining is diagnosed, the significance of nucleoplasty is completely annulled. The operation of choice for already formed lumbar hernias is microdiscectomy or endoscopy.

Separately, it is worth highlighting the fact that elderly patients (after 50-55 years) do not undergo puncture surgery on lumbar discs. Experts explain this by the fact that, due to age-related aging, the lumbar intervertebral discs at this age are too severely dehydrated. This fact indicates the intractability of the unacceptably dehydrated fibrous ring to reverse retraction in the protrusion zone when using any type of nucleoplasty. And, consequently, the ineffectiveness of such procedures in elderly patients.

Diagnostics

If symptoms of L4-L5 protrusion, and especially radicular syndrome, appear, it is important to contact a chiropractor, vertebrologist or neurologist as soon as possible. The doctor will conduct a thorough survey of the patient, find out the nature of the complaints about the state of health, lifestyle features, whether there are chronic diseases, etc.

After this, he will proceed directly to the inspection. During it, he will find the most painful areas, conduct the necessary neurological tests in this situation to assess the degree of neurological deficit and will be able to suggest damage to the L4-L5 intervertebral disc.

But this data is not enough to develop effective treatment tactics. It is important to have a clear understanding of the location, type, size of the protrusion, and the condition of the surrounding tissues. Therefore, patients are required to be prescribed instrumental diagnostic methods. It can be:

• MRI;
• CT;
• X-ray.

If possible, preference is always given to MRI, since this diagnostic method allows you to collect the maximum amount of accurate information about the condition of the intervertebral discs and is completely safe. With its help, you can not only determine the presence of a protrusion in the L4-L5 intervertebral disc, but also determine with high accuracy its size, position in the spinal canal, etc. But MRI is expensive and cannot be performed if there are metal implants in the patient’s body with diamagnetic properties. Therefore, in such situations, patients are prescribed a CT scan or x-ray of the spine.

In some situations, it is recommended to conduct electroneuromyography, designed to assess the functional state of muscles and peripheral nerves.

In our clinic you can also learn in more detail about the composition of your body and the state of the vascular system, which is involved in the blood supply to internal organs, musculoskeletal muscles, and the brain. Our experienced doctors will explain the data obtained to you in detail. Bioimpendansometry calculates the ratio of fat, muscle, bone and skeletal mass, total fluid in the body, and basal metabolic rate. The intensity of recommended physical activity depends on the state of muscle mass. Metabolic processes, in turn, affect the body's ability to recover. Based on the indicators of active cell mass, one can judge the level of physical activity and nutritional balance. This simple and quick test helps us identify disturbances in the endocrine system and take the necessary measures. In addition, it is also very important for us to know the condition of blood vessels for the prevention of diseases such as heart attacks, hypertension, heart failure, diabetes and much more. Angioscan allows you to determine such important indicators as the biological age of blood vessels, their stiffness, stress index (which indicates heart rate), and blood oxygen saturation. Such screening will be useful for men and women over 30, athletes, those undergoing long-term and severe treatment, as well as everyone who monitors their health.

In this case, body composition analysis gives us information that adipose tissue predominates in the body, and the bone-muscle component is in relative deficiency. These data will help the rehabilitation doctor competently draw up a physical activity plan, taking into account the individual characteristics of the patient.

Recovery after surgery

After a minimally invasive simple session, the patient is activated after 2-3 hours. Most of those operated on notice noticeable improvements within the first hours after minimally invasive surgery. Perhaps, immediately after activation, he will be allowed to go home on his own. But in order to avoid postoperative complications, which are not excluded even after percutaneous (the most gentle) surgery, the following are prescribed:

• antibiotic therapy (against infections and suppurations);
• taking vascular medications (against limb thrombosis, thromboembolism);
• a calm physical regimen, especially gentle on the lower back during the recovery period;
• special physical therapy for good restoration of the operated area, muscle strengthening, and prevention of relapses;
• wearing a support corset during rehabilitation;
• ban on lifting weights, lifelong refusal from heavy sports.

In total, rehabilitation measures take 2 months. But this does not mean that during these 2 months a person will be limited from walking, going to work, doing household chores, etc. No, with a successful intervention, patients even go to work within 3-5 days. However, non-compliance with specific rehabilitation and lifelong regimens, which the doctor thoroughly informs about upon discharge, is associated with high risks of postoperative complications. The first among them is the rapid resumption and more progressive course of protrusion.

Alternative techniques

Only comprehensive treatment can ensure complete recovery, which, in addition to traditional methods, also includes alternative ones:

• hirudotherapy – leeches are placed on the area where the hernia is located;
• ozone therapy – ozone preparations are injected into damaged areas using injections;
• homeosinia – homeopathic medicines are injected into reflex points.

The combination of innovative techniques with time-tested methods allows in 90% of cases to cure a herniated disc without surgery. And if you follow simple preventive measures, the disease will no longer remind you of itself.