Spinal Nerve Syndromes PDF

Spinal Root Syndromes CHRISTINA LENK, MD OCTOBER 9, 2024 [email protected]  Objectives  Review anatomy of the spinal cord and nerve roots  Discuss various symptoms of radiculopathy involving the upper and lower extremities  Review...

Spinal Root Syndromes CHRISTINA LENK, MD OCTOBER 9, 2024 [email protected]  Objectives  Review anatomy of the spinal cord and nerve roots  Discuss various symptoms of radiculopathy involving the upper and lower extremities  Review causes of radiculopathy  Discuss cauda equina syndrome  Discuss conus medullaris syndrome  Anatomy  31 pairs of spinal nerves run through the intervertebral foramina  8 cervical  12 thoracic  5 lumbar  5 sacral  1 coccygeal  Each cervical nerve root exits above its corresponding vertebral segment, except the C8 nerve root exits below C7 and above T1  At thoracic, lumbar, and sacral levels, each root exits below its corresponding vertebral level  In the adult, the spinal cord is shorter than the spinal column, ending usually between L1 and L2  The lumbar and sacral roots descend caudally from the spinal cord to reach the individual intervertebral foramina, forming the cauda equina Spinal Cord Anatomy and Localization Hardy, Todd A. CONTINUUM: Lifelong Learning in Neurology27(1):12- 29, February 2021. doi: 10.1212/CON.0000000000000899 The gross anatomy of the spinal cord and adjacent spinal nerve roots.Reprinted with permission from Moore KL, et al, Wolters Kluwer/Lippincott Williams & Wilkins.1 © 2014 Lippincott Williams & Wilkins.  Terminology  Upper motor neuron  Brain and spinal cord  Conus medullaris  Lower motor neuron  Nerve roots  Cauda equina  Peripheral nerves  Terminology  Dermatome  The sensory distribution of a single nerve root  Myotome  The collection of muscles with significant innervation from a single root is called a myotome  Paresthesia  Subjective tingling sensation due to pathology of a nerve or nerve pathway  Terminology  Radiculopathy  A pathologic process affecting the nerve root  Causes can be divided into compressive and nondegenerative etiologies  The majority arise from nerve root compression  Predominant mechanisms are cervical spondylosis and disc herniation  Nerve Root Compression  Spondylosis  A general term for nonspecific, degenerative changes of the spine  Often is a cause of canal stenosis, but the two terms are not interchangeable  Although all causes of spondylosis have not been well defined, aging is an important factor  Degenerative changes occur in the vertebral discs, the facet joints and uncovertebral joints, and the vertebral bodies  Gradually, there is bone formation in these areas, which is called an osteophyte  More than 75% of all disc protrusions causing radiculopathy involve the L5 or S1 nerve roots  Risk factors for developing radiculopathy include manual labor involving heavy lifting, driving, or operation of vibrating equipment  History of chronic smoking increases the risk of developing radiculopathy  Cervical Spine  The spinal canal is widest in the upper part of the cervical spine  At the C1- C3 levels, the maximal anterior posterior dimension of the canal is 16 to 30 mm, and at the C4 - C7 levels it is 14 to 23 mm  The canal narrows an additional 2 to 3 mm with maximal neck extension  The upper cervical spine is responsible for rotational movements of the head  The lower cervical spine is responsible for flexion and extension movements of the head  Spondylotic disease most commonly occurs in the lower cervical spine  Lumbar Spine  The lumbosacral spine is susceptible to disc herniations because of its mobility from flexion, extension, and torsion  75% of flexion and extension occurs at the L5-S1 joint but it has limited torsion  20% of flexion and extension occurs at L4-L5  The remaining 5% occurs between L1 and L3  The L4-L5 and L5-S1 levels are most susceptible to injuries from routine movements of the spine, so 90 - 95 % of compressive radiculopathies occur at these levels  The incidence of radiculopathies is split somewhat evenly between L4-L5 and L5- S1, as the lack of torsion at L5-S1 helps to increase its stability despite its higher degree of flexion and extension  Nerve Root Compression  Disc herniation  The intervertebral disc is composed of a tough, ligamentous outer annulus and a gelatinous inner nucleus pulposus  The combination of intervertebral pressure and degeneration of the ligamentous fibers can lead to a tear in the annulus, allowing the nucleus pulposus to prolapse through the annulus  Inflammation and radicular symptoms develop if the prolapsed material presses on a nerve root  Disc herniation is most likely to result in root compression and radicular symptoms if it occurs laterally, whereas spinal cord compression and myelopathy can occur if there is herniation of a large midline disc  Radiculopathy Symptoms  Symptoms develop more acutely when caused by a herniated disc  Onset is generally slower when due to spondylosis  Pain in the neck typically radiates into the arm or leg in a dermatomal pattern  Pain may be in the cervical region, the upper limb, the shoulder, or the interscapular region  May be atypical and present as chest pain (pseudo-angina), breast pain, or facial pain  Sensory loss in radiculopathy is frequently mild or absent due to the extensive overlap of dermatomes  Paresthesia or numbness in a root distribution occurs in 80% of patients  Subjective weakness is less common than paresthesias  A sharp demarcation of sensory loss is frequently seen in peripheral nerve lesions, and this finding may be a helpful distinguishing feature  In the presence of pain, it can be difficult to perform an accurate motor examination  The reflex exam is a more objective test of nerve root function  The diagnosis is further supported when the symptoms are exacerbated by Valsalva maneuvers (cough, sneeze, or strain)  Indicates stretching of the dura at an intraspinal point of compression  Lower cervical roots, particularly C7, are more frequently affected by compression than higher cervical roots  C7 is the most frequently affected nerve root, accounting for approximately 70% of patients with cervical radiculopathy  C6 root involvement was found in approximately 20%  Involvement of the C5, C8, and T1 levels together account for the remaining 10%  History  An accurate history is most important in the diagnosis of radiculopathy  Chief complaint: Numbness, pain, weakness, location of symptoms?  What activities increase or decrease the symptoms?  What was the mechanism of injury?  Ask about occupational risk factors and history of trauma or triggers  Radicular pain is usually described by patients as "electrical shocks" or "shooting pains" that radiate from the buttock to the foot or neck to the hand  But can also be experienced as aching pain referred to the medial border of the scapula and called “shoulder pain” by patients  In many cases, cervical radiculopathy can be diagnosed based on the patient history alone  Upper Extremity Examination  Spurling test  Designed to reproduce symptoms by compression of the affected nerve root  Passive cervical extension with rotation to the affected side and axial compression  Cervical extension induces/reproduces posterior bulging of the intervertebral disk  Rotation of the head causes narrowing of the neuroforamina in the cervical spine  Axial compression is applied to amplify the effects with the aim of exaggerating the nerve root compression  Most commonly used (highest specificity; only moderate sensitivity)  Shoulder abduction test (looks for C5-C7 nerve root compression)  Performed by asking the patient to rest the hand on the top of the head (positive test results in relief of symptoms)  Symptoms may increase with the arm hanging at the side of the body  Valsalva maneuver  Neck distraction test  Traction is placed on the neck while the patient is lying supine  Reflexes  C5 - biceps and brachioradialis  C6 - brachioradialis  C7 - triceps  L4 - quadriceps  S1 - Achilles ► 0 – Absent reflex with no evidence of contraction ► 1+ - Decreased, but still present (hypo-reflexic) ► 2+ - Normal reflex ► 3+ - Hyper-reflexic ► 4+ - Clonus  Lower Extremity Examination  Straight leg test  Performed by passively raising one leg into the air 30-60 degrees from the exam table  Creates increased tension on the sciatic nerve  Reproduction of the patient's symptoms is a positive test suggestive of lower lumbar nerve root involvement (L4 to S1)  Reverse straight leg  Patient's symptoms are reproduced by extending the hip and flexing the knee with the patient in the prone position  This will stretch the femoral nerve and the L2 to L4 nerve roots  Reproduction of radicular symptoms can also be produced by placing the patient in a seated position with the neck in full flexion and knees in full extension (slump test)  Examination Findings  Bowstring sign  Relief of radicular pain when the knee is flexed during a positive straight leg raise  Important Points to Remember  Cervical radiculopathy is almost always unilateral, although, in rare cases, both nerves at a given level may be impacted  On physical examination, positioning the patient to isolate individual reflexes is key  Given the individual variation in reflexes, comparing side to side is more important than overall magnitude  If there is nerve impingement, the affected side will be reduced relative to the unaffected side  Reduction in strength of muscles innervated by the affected nerve is also a significant physical finding  L1 radiculopathy  Herniation at the L1 level is rare, and thus L1 radiculopathy is uncommon  Symptoms on presentation generally involve pain, paresthesia, and sensory loss in the inguinal region  Rarely, minor hip flexion weakness is present  L2/L3/L4 radiculopathy  There is marked overlap of the L2, L3, and L4 innervation of the anterior thigh muscles, making it difficult to differentiate these spinal nerve root levels based on symptoms, neurologic examination, or electrodiagnostic testing  These are generally considered as a group  Most commonly involved in older patients with symptoms of spinal stenosis  L5 radiculopathy  The most common radiculopathy affecting the lumbosacral spine  Presents with back pain that radiates down the lateral aspect of the leg into the foot  Examination reveals reduced strength of foot dorsiflexion, toe extension, foot inversion, and foot eversion and occasionally weakness of leg abduction  Atrophy may be present in the extensor digitorum brevis muscle of the foot and the tibialis anterior muscle  Sensory loss is confined to the lateral aspect of the lower leg and dorsum of the foot, but may be obvious only when testing sharp sensation in the web space between the first and second digits  Reflexes are generally normal  S1 radiculopathy  Pain radiates down the posterior aspect of the leg into the foot  Weakness of plantar flexion (gastrocnemius muscle) is specific  There may also be weakness of leg extension and knee flexion  Sensation is generally reduced on the posterior aspect of the leg and the lateral edge of the foot  Ankle reflex loss is typical  S2/S3/S4 radiculopathy  Structural radiculopathies at these lower levels are less common than other lumbosacral radiculopathies, but may be caused by a large central disc compressing the nerve roots intrathecally at a higher level  Patients can present with sacral or buttock pain that radiates down the posterior aspect of the leg or into the perineum  Weakness is minimal, with urinary and fecal incontinence as well as sexual dysfunction present  Evaluation  Plain x-rays  CT scan  MRI  EMG/NCS  Myelogram  Treatment  Pain control  Muscle relaxants  Physical therapy  Epidural steroid injections  Surgical intervention Non-Degenerative Radiculopathies  Tend to affect the ventral and dorsal root more diffusely than compressive etiologies  In contrast to most compressive types, nondegenerative radiculopathies may also affect the dorsal root ganglion  The deficit may span multiple myotomes and dermatomes, leading to motor and sensory deficits that are more complete than are typical for a compressive radiculopathy  Non-Degenerative Causes of Radiculopathy  Diabetes mellitus  Sarcoid  Nerve root trauma  Infiltrative conditions:  Nerve root infarction  Lymphoma  Nerve root avulsion  Carcinomatous meningitis  Infectious or granulomatous conditions:  Herpes zoster  Inflammatory conditions:  Lyme disease  Guillain-Barré syndrome  Tuberculosis  Chronic inflammatory demyelinating  Human immunodeficiency virus (HIV) polyneuropathy  Syphilis  Vasculitis with nerve root infarction  Brucellosis  Cytomegalovirus  Histiocytosis X  Herpes Zoster  Caused by varicella zoster virus  Colonizes the dorsal root ganglia after initial infection and may remain latent for years  Reactivation is associated with a hemorrhagic lymphocytic infiltration of the ventral roots  Symptoms include  An erythematous vesicular maculopapular rash in the dermatome of the affected root that lasts for three to five days  Sensory changes characterized by severe burning or tingling pain  Most likely to involve the thoracic dermatomes and the face  Risk Factors ► Age >60 years (8-10x increased risk ► Underlying malignancy ► Especially lymphoproliferative cancers ► Immunosuppression (due to altered cell-mediated immunity) ► Diabetes ► Surgical trauma ► UV light  Disease Course ► 80 – 90% resolve spontaneously over 6 months ► Chronic pain (Post-Herpetic Neuralgia) ► Pain lasting greater than 2-3 months after rash develops ► Occurs in about 5% of cases ► Occurrence correlates with ► Severity of the rash ► Severity of acute pain at onset  Treatment  Prevention with Shingrix vaccine  Antiviral medication started