Radiculopathy is a diagnosis commonly made by physicians in primary care specialities, chiropractic, orthopedics, physiatry, and neurology. The diagnosis may be suggested by symptoms of pain, numbness, and weakness in a pattern consistent with the distribution of a particular nerve root. Neck pain or back pain may also be present. Physical examination may reveal motor and sensory deficits in the distribution of a nerve root. In the case of cervical radiculopathy, Spurling's test may elicit or reproduce symptoms radiating down the arm. In the case of lumbosacral radiculopathy, a Straight leg raise maneuver may exacerbate radiculopathic symptoms. Deep tendon reflexes (also known as a Stretch reflex) may be diminished or absent in areas innervated by a particular nerve root.

For further workup, the American College of Radiology recommends that projectional radiography is the most appropriate initial study in all patients with chronic neck pain. Two additional diagnostic tests that may be of use are magnetic resonance imaging and electrodiagnostic testing. Magnetic resonance imaging (MRI) of the portion of the spine where radiculopathy is suspected may reveal evidence of degenerative change, arthritic disease, or another explanatory lesion responsible for the patient's symptoms. Electrodiagnostic testing, consisting of NCS (Nerve conduction study) and EMG (Electromyography), is also a powerful diagnostic tool that may show nerve root injury in suspected areas. On nerve conduction studies, the pattern of diminished Compound muscle action potential and normal sensory nerve action potential may be seen given that the lesion is proximal to the Posterior root ganglion. Needle EMG is the more sensitive portion of the test, and may reveal active denervation in the distribution of the involved nerve root, and neurogenic-appearing voluntary motor units in more chronic radiculopathies. Given the key role of electrodiagnostic testing in the diagnosis of acute and chronic radiculopathies, the American Association of Neuromuscular & Electrodiagnostic Medicine has issued evidence-based practice guidelines, for the diagnosis of both cervical and lumbosacral radiculopathies. The American Association of Neuromuscular & Electrodiagnostic Medicine has also participated in the Choosing Wisely Campaign and several of their recommendations relate to what tests are unnecessary for neck and back pain.

Electrophysiologic testing is an essential part of the evaluation of Anterior interosseous nerve syndromes. Nerve conduction studies may be normal or show pronator quadratus latency.⁠⁠

Electromyography (EMG) is generally most useful and will reveal abnormalities in the flexor pollicis longus, flexor digitorum profundus I and II and pronator quadratus muscles.⁠⁠

The role or MRI and ultrasound imaging in the diagnosis of Kiloh-Nevin syndrome is unclear.⁠

If asked to make the "OK" sign, patients will make a triangle sign instead.

This 'Pinch-Test' exposes the weakness of the Flexor pollicis longus muscle and the flexor digitorum profundus I leading to weakness of the flexion of the distal phalanges of the thumb and index finger. This results in impairment of the pincer movement and the patient will have difficulty picking up a small item, such as a coin, from a flat surface.

Bernese periacetabular osteotomy resulted in major nerve deficits in the sciatic or femoral nerves in 2.1% of 1760 patients, of whom approximately half experienced complete recovery within a mean of 5.5 months.

Sciatic nerve exploration can be done by endoscopy in a minimally invasive procedure to assess lesions of the nerve. Endoscopic treatment for sciatic nerve entrapment has been investigated in deep gluteal syndrome; "Patients were treated with sciatic nerve decompression by resection of fibrovascular scar bands, piriformis tendon release, obturator internus, or quadratus femoris or by hamstring tendon scarring."

Signals from the sciatic nerve and it branches can be blocked, in order to interrupted transmission of pain signal from the innervation area, by performing a regional nerve blockade called a sciatic nerve block.

The symptoms and signs depend on which nerve is affected, where along its length the nerve is affected, and how severely the nerve is affected. Positive sensory symptoms are usually the earliest to occur, particularly tingling and neuropathic pain, followed or accompanied by reduced sensation or complete numbness. Muscle weakness is usually noticed later, and is often associated with muscle atrophy.

A compression neuropathy can usually be diagnosed confidently on the basis of the symptoms and signs alone. However, nerve conduction studies are helpful in confirming the diagnosis, quantifying the severity, and ruling out involvement of other nerves (suggesting a mononeuritis multiplex or polyneuropathy). A scan is not usually necessary, but may be helpful if a tumour or other local compressive lesion is suspected.Nerve injury, as a mononeuropathy, may cause similar symptoms to compression neuropathy. This may occasionally cause diagnostic confusion, particularly if the patient does not remember the injury and there are no obvious physical signs to suggest it.The symptoms and signs of each particular syndrome are discussed on the relevant pages, listed below.

The prognosis for complete recovery is dependent upon many factors. The most important of these is the severity and duration of compression upon the damaged nerve(s). Generally, the longer the time before intervention to remove the compression causing nerve damage, the greater the damage caused to the nerve(s).

Damage can be so severe that nerve regrowth is impossible, and the nerve damage will be permanent. In cases where the nerve has been damaged but is still capable of regrowth, recovery time is widely variable. Surgical intervention with decompression of the cauda equina can assist recovery. Delayed or severe nerve damage can mean up to several years' recovery time because nerve growth is exceptionally slow.

Review of the literature indicates that around 50-70% of patients have urinary retention (CES-R) on presentation with 30-50% having an incomplete syndrome (CES-I). The latter group, especially if the history is less than a few days, usually requires emergency MRI to confirm the diagnosis followed by prompt decompression. CES-I with its more favourable prognosis may become CES-R at a later stage.

People who suffer from neurotmesis often face a poor prognosis. They will more than likely never regain full functionality of the affected nerve, but surgical techniques do give people a better chance at regaining some function. Current research is focused on new ways to regenerate nerves and advance surgical techniques.

Surgical decompression can give excellent results if the clinical picture and the EMG suggest a compression neuropathy.

In brachial plexus neuritis, conservative management may be more appropriate.

Spontaneous recovery has been reported, but is said to be delayed and incomplete.

There is a role for physiotherapy and this should be directed specifically towards the pattern of pain and symptoms. Soft tissue massage, stretches and exercises to directly mobilise the nerve tissue may be used.⁠

The diagnosis may be confirmed by an EMG examination in 5 to 7 days. The evidence of denervation will be evident. If there is no nerve conduction 72 hours after the injury, then avulsion is most likely..

The most advanced diagnostic method is MR imaging of the brachial plexus using a high Tesla MRI scanner like 1.5 T or more. MR helps aid in the assessment of the injuries in specific context of site, extent and the nerve roots involved. In addition, assessment of the cervical cord and post traumatic changes in soft tissues may also be visualised.

With Seddon's classification of nerve injuries, it is often tough to identify whether a particular nerve injury is neurotmesis, or axonotmesis, which has damage to the nerve fibres but preservation of the nerve trunk. Due to the damage involved in both of these conditions they will both show paralysis of muscles that are supplied by nerves below the site of the lesion, and will have sensory deficits in accordance with the individual nerves that are damaged. The only way to know for sure if a nerve injury is in fact neurotmesis is to allow for the normal progression of nerve regeneration to take place (nerves regenerate at a rate of approximately 2–4 mm/day proximal to the lesion), and if, after that time, there is still profound muscle paralysis and degeneration in these areas, then it is likely to have been a neurotmesis injury.

Neurotmesis is diagnosed through clinical evaluation of symptoms, physical evaluation, and other diagnostic studies. Patients often undergo a series of muscle strength tests, sensory exam which includes feeling the sensation of light touch, pinprick, vibration, and others. Other tests involved with diagnosis of nerve injury are electromyography (EMG) and nerve conduction studies (NCS). These help to distinguish upper from lower motor neuron disorder as well as diagnose primary muscle disease.

Examination for pain sensation, by pinprick, shows leg (lumbar nerves) analgesia with perineal (sacral nerves) escape. The maintenance of perineal sensation with absence of pain sensation over the lumbar nerve roots is typical for an extra-medullary and intra-thecal (outside the cord and within the dural sheath) process. Inability to walk, with this unusual sensory examination completes a triad of signs and usually represents spinal tuberculosis. The triad is paraplegia with lumbar loss of pain sensation and presence of perineal altered sensation.

Diagnosis is usually confirmed by an MRI scan or CT scan, depending on availability. Early surgery in acute onset of severe cases has been reported to be important.

While conservative approaches for rehabilitation are ideal, some patients will not improve and surgery is still an option. Patients with large cervical disk bulges may be recommended for surgery, however most often conservative management will help the herniation regress naturally. Procedures such as foraminotomy, laminotomy, or discectomy may be considered by neurosurgeons and orthopedic surgeons.

When an underlying medical condition is causing the neuropathy, treatment should first be directed at this condition. For example, if weight gain is the underlying cause, then a weight loss program is the most appropriate treatment. Compression neuropathy occurring in pregnancy often resolves after delivery, so no specific treatment is usually required. Some compression neuropathies are amenable to surgery: carpal tunnel syndrome and cubital tunnel syndrome are two common examples. Whether or not it is appropriate to offer surgery in any particular case depends on the severity of the symptoms, the risks of the proposed operation, and the prognosis if untreated. After surgery, the symptoms may resolve completely, but if the compression was sufficiently severe or prolonged then the nerve may not recover fully and some symptoms may persist. Drug treatment may be useful for an underlying condition (including peripheral oedema), or for ameliorating neuropathic pain.

Treatment is directed at the pathology causing the paralysis. If it is because of trauma such as a gunshot or knife wound, there may be other life-threatening conditions such as bleeding or major organ damage which should be dealt with on an emergent basis. If the syndrome is caused by a spinal fracture, this should be identified and treated appropriately. Although steroids may be used to decrease cord swelling and inflammation, the usual therapy for spinal cord injury is expectant.

The diagnosis depends on appropriate patient history backed by imaging studies like X ray and MRI. Lumbosacral spine radiographs help in the identification of the skeletal abnormality. MRI helps in confirmation.

Diagnosis of tumefactive MS is commonly carried out using magnetic resonance imaging (MRI) and proton MR spectroscopy (H-MRS). Diagnosis is difficult as tumefactive MS may mimic the clinical and MRI characteristics of a glioma or a cerebral abscess. However, as compared to tumors and abscesses, tumefactive lesions have an open-ring enhancement as opposed to a complete ring enhancement. Even with this information, multiple imaging technologies have to be used together with biochemical tests for accurate diagnosis of tumefactive MS.

Tumefactive demyelination is distinguished from tumor by the presence of multiple lesions, absence of cortical involvement, and decrease in lesion size or detection of new lesions on serial imaging

Electrical stimulation can promote nerve regeneration. The frequency of stimulation is an important factor in the success of both quality and quantity of axon regeneration as well as growth of the surrounding myelin and blood vessels that support the axon. Histological analysis and measurement of regeneration showed that low frequency stimulation had a more successful outcome than high frequency stimulation on regeneration of damaged sciatic nerves.

Surgery can be done in case a nerve has become cut or otherwise divided. Recovery of a nerve after surgical repair depends mainly on the age of the patient. Young children can recover close-to-normal nerve function. In contrast, a patient over 60 years old with a cut nerve in the hand would expect to recover only protective sensation, that is, the ability to distinguish hot/cold or sharp/dull. Many other factors also affect nerve recovery. The use of autologous nerve grafting procedures that involve redirection of regenerative donor nerve fibers into the graft conduit has been successful in restoring target muscle function. Localized delivery of soluble neurotrophic factors may help promote the rate of axon regeneration observed within these graft conduits.

An expanding area of nerve regeneration research deals with the development of scaffolding and bio-conduits. Scaffolding developed from biomaterial would be useful in nerve regeneration if they successfully exhibit essentially the same role as the endoneurial tubes and Schwann cell do in guiding regrowing axons.

Several different types of magnetic resonance imaging (MRI) may be employed in diagnosis: MRI without contrast, Gd contrast enhanced T1-weighted MRI (GdT1W) or T2-weighted enhanced MRI (T2W or T2*W). Non-contrast enhanced MRI is considerably less expensive than any of the contrast enhanced MRI scans. The gold standard in diagnosis is GdT1W MRI.

The reliability of non-contrast enhanced MRI is highly dependent on the sequence of scans, and the experience of the operator.

The severity of brachial plexus injury is determined by the type of nerve damage. There are several different classification systems for grading the severity of nerve and brachial plexus injuries. Most systems attempt to correlate the degree of injury with symptoms, pathology and prognosis. Seddon's classification, devised in 1943, continues to be used, and is based on three main types of nerve fiber injury, and whether there is continuity of the nerve.

1. Neurapraxia: The mildest form of nerve injury. It involves an interruption of the nerve conduction without loss of continuity of the axon. Recovery takes place without wallerian degeneration.

2. Axonotmesis: Involves axonal degeneration, with loss of the relative continuity of the axon and its covering of myelin, but preservation of the connective tissue framework of the nerve (the encapsulating tissue, the epineurium and perineurium, are preserved).

3. Neurotmesis: The most severe form of nerve injury, in which the nerve is completely disrupted by contusion, traction or laceration. Not only the axon, but the encapsulating connective tissue lose their continuity. The most extreme degree of neurotmesis is transsection, although most neurotmetic injuries do not produce gross loss of continuity of the nerve but rather, internal disruption of the nerve architecture sufficient to involve perineurium and endoneurium as well as axons and their covering. It requires surgery, with unpredictable recovery.

A more recent and commonly used system described by the late Sir Sydney Sunderland, divides nerve injuries into five degrees: first degree or neurapraxia, following on from Seddon, in which the insulation around the nerve called myelin is damaged but the nerve itself is spared, and second through fifth degree, which denotes increasing severity of injury. With fifth degree injuries, the nerve is completely divided.

Before the advent of MRI, electronystagmography and Computed Tomography were employed for diagnosis of acoustic neuroma.

Because there are various causes for back injuries, prevention must be comprehensive. Back injuries are predominant in manual labor so the majority low back pain prevention methods have been applied primarily toward biomechanics Prevention must come from multiple sources such as education, proper body mechanics, and physical fitness.

Surgery may be useful in those with a herniated disc that is causing significant pain radiating into the leg, significant leg weakness, bladder problems, or loss of bowel control. Discectomy (the partial removal of a disc that is causing leg pain) can provide pain relief sooner than nonsurgical treatments. Discectomy has better outcomes at one year but not at four to ten years. The less invasive microdiscectomy has not been shown to result in a significantly different outcome than regular discectomy with respect to pain. It might however have less risk of infection.

The presence of cauda equina syndrome (in which there is incontinence, weakness and genital numbness) is considered a medical emergency requiring immediate attention and possibly surgical decompression. Regarding the role of surgery for failed medical therapy in people without a significant neurological deficit, a Cochrane review concluded that "limited evidence is now available to support some aspects of surgical practice".

MRI diagnosis is based on lesions that are disseminated in time and space, meaning that there are multiple episodes and consisting of more than one area. There are two kinds of MRI used in the diagnosis of tumefactive MS, T1-weighted imaging and T2-weighted imaging. Using T1-weighted imaging, the lesions are displayed with low signal intensity, meaning that the lesions appear darker than the rest of the brain. Using T2-weighted imaging, the lesions appear with high signal intensity, meaning that the lesions appear white and brighter than the rest of the brain. When T1-weighted imaging is contrast-enhanced through the addition of gadolinium, the open ring enhancement can be viewed as a white ring around the lesion. A more specific MRI, Fluid attenuation inversion recovery (FLAIR) MRI show the signal intensity of the brain. Subjects with tumefactive multiple sclerosis may see a reduction of diffusion of the white matter in the affected area of the brain.

Magnetic resonance imaging (MRI) is the imaging of choice in spinal cord lesions.

Brown-Séquard syndrome is an incomplete spinal cord lesion characterized by findings on clinical examination which reflect hemisection of the spinal cord (cutting the spinal cord in half on one or the other side). It is diagnosed by finding motor (muscle) paralysis on the same (ipsilateral) side as the lesion and deficits in pain and temperature sensation on the opposite (contralateral) side. This is called ipsilateral hemiplegia and contralateral pain and temperature sensation deficits. The loss of sensation on the opposite side of the lesion is because the nerve fibers of the spinothalamic tract (which carry information about pain and temperature) crossover once they meet the spinal cord from the peripheries.

Diagnosis of Harlequin syndrome is made when the individual has consistent signs and symptoms of the condition, therefore, it is made by clinical observation. In addition, a neurologist or primary care physician may require an MRI test to rule out similar disorders such as Horner's syndrome, Adie's syndrome, and Ross' syndrome. In an MRI, a radiologist may observe areas near brain or spinal cord for lesions, or any damage to the nerve endings. It is also important that the clinician rules out traumatic causes by performing autonomic function tests. Such tests includes the following: tilt table test, orthostatic blood pressure measurement, head-up test, valsalva maneuver, thermoregulatory sweat test, tendon reflex test, and electrocardiography (ECG). CT scan of the heart and lungs may also be performed to rule out a structural underlying lesion. The medical history of the individual should be carefully noted.