Definitions and discussion

Narrowing of the spinal canal causing potential neurologic symptoms due to compression of the spinal cord, nerve roots or spinal nerves

• Synonym: intermittent claudication

Aetiology

Usually affects 50 years and older age group

Stenosis may be central or lateral and caused by bone, soft tissue or both

May be caused by:

• Congenital defects, spondylosis
• Disc herniation
• Proliferation of the ligamentum flavum
• Neoplasm, infection

History, symptoms and signs

• May have presented with previous episodes of lower back pain which has now changed to lower limb pain or neurological deficit
• Major or minor trauma
• Patients may present with an inconsistent pattern of back and leg pain that may increase with activity and is relieved by rest (may resemble the clinical presentation of vascular claudication)
• Forward flexion may relieve the pain
• Increased stiffness in the lower back
• Diffuse pain that may be unilateral or bilateral
• Possible neurologic deficits
• Loss of lumbar lordosis and posterior pelvic till, may walk or stand in more of a flexed position
• Difficulty walking if neurological symptoms affecting the lower limbs
• Possible muscle spasm on inspection and palpation
• Decreased range of motion due to increased stiffness; flexion may relieve leg pain whilst extension, lateral flexion and rotation may increase the leg pain
• May identify the appearance of disc bulges in asymptomatic cases
• Differentiate between lateral canal stenosis and central canal stenosis

Management

• Adjust
• Mobilise
• Flexion distraction
• Soft tissue massage, ischemic compression and dry needling
• Modalities: IFC, ultrasound, TENS, laser, ice, heat
• Patient education/ergonomics
• Stretching, strengthening, proprioception
• Use flexion type movements, positions. Avoid extension type movements.

 Introduction

• Lumbar stenosis may be asymptomatic
• Lumbar stenosis may lead to pain and neurological symptoms or the condition neurogenic claudication (specific symptomology)
• Spinal Stenosis Work Group of the North American Spine Society Clinical Guidelines Committee (2008) definition: clinical syndrome of buttock or lower extremity pain, which may occur with or without back pain; associated with diminished space available for the neural and vascular elements in the lumbar spine.

Pathophysiology

Lumbar spine stenosis can be classified into:

• Aetiology of LSS
• Anatomic location and tissues involved in narrowing

Aetiology of LSS can be divided into:

1. Developmental/congenital
2. Acquired

Developmental/congenital

• Idiopathic (e.g. short pedicles, thickened lamina and facets)
• Achondroplasia
• Morquio Syndrome
• Hypophosphatemia Vit D-Resistant Rickets
• Spinal Dysraphism (Lipoma, Myelomeningocele)

Acquired

• Degenerative
  • Spondylosis (IVD herniation, hypertrophy of the ligamentum flavum, hypertrophy of the facet joints and osteophyte formation)
  • SLT
  • Ossification of Ligamentum Flavum
  • Ossification of the PLL
  • Intraspinal Synovial cysts
• Metabolic or Endocrine
  • Osteoporosis
  • Acromegaly
  • Pseudogout
  • Renal osteodystrophy
  • Hypoparathyroidism
  • Epidural lipomatosis
  • Fluorosis
• Skeletal
  • Pagets disease
  • Ankylosing spondylitis
  • DISH
  • Rheumatoid Arthritis
• Traumatic
  • Burst fracture
  • Laminectomy
  • Kyphosis/scoliosis
• Postoperative
  • Laminectomy
  • Fusion
  • Fibrosis

Anatomic location and tissues involved in narrowing can classify LSS into:

• Central LSS: involves the narrowing of the spinal canal around nerve roots of the cauda equina within the dural sac
• Spinal cord and nerve root compression can also be based on location within the central canal:
• Extradural: most common causes being due to degenerative processes (disc herniation or spondylosis), metastatic disease and spinal trauma
• Intradural: may be found within the spinal cord substance (intramedullary) or on its surface (extramedullary)
• Intradural extramedullary lesions are mainly tumours and are almost always benign. They include neurofibromas and meningiomas which may be treated surgically with relatively low morbidity
• Intradural intramedullary lesions are less common. They include diffuse astrocytoma’s (cannot be removed surgically) and ependymoma (may sometimes be removed with difficulty). Multiple sclerosis may mimic an intramedullary tumour
• Lateral LSS: occurs when the nerve root becomes encroached upon in the lateral canal (extends from the dural sac to the IVF) or IVF
• Most common type of stenosis is due to degenerative processes i.e. degenerative LSS
• In patients with a congenitally borderline or narrow canal, relatively mild degenerative changes are sufficient to cause spinal stenosis
• Degenerative SLT develops when there are severe degenerative changes and excess motion at the facet joints. The entire vertebra shifts forwards which then narrows the spinal canal and symptoms of spinal stenosis are common
• With isthmic SLT, the pars defect divides the vertebra into an anterior part (VB, pedicles, transverse processes and superior articular facet) and posterior part (inferior articular facet, laminae and spinous process). The anterior portion slips forward and leaves the posterior portion behind. This therefore elongates the A-P dimension of the spinal canal and therefore spinal stenosis is uncommon
• In the cervical spine, the most common cause of lateral canal stenosis is hypertrophy of the uncovertebral joints
• Nontraumatic spinal stenosis of the thoracic spine is rare

Clinical presentation

According to Amundsen et al (1995), the clinical symptoms of LSS include:

• Bilateral or unilateral leg pain (present in 100% of their patients)
• Lower back pain (present in 95% of their patients)
• Sensory disturbances in the legs (present in 70% of their patients)
• Weakness in the legs (present in 33% of their patients)
• Neurogenic claudication (present in 91% of their patients)

Hallmark signs or symptoms of LSS (with neurogenic claudication) is the appearance of leg pain with standing: leg pain is exacerbated by prolonged walking (especially with lumbar spine extension) and relieved by resting in a flexed lumbar spine position. The following *red flags* in patients with lower back pain may suggest serious underlying pathology:

• Cancer (risk factors include those over 50 years of age, previous history of cancer, unexplained weight loss, no relief of pain with bed rest, pain at rest and pain that is worse at night)
• Infection (risk factors include immunocompromised states, persistent fever, intravenous drug use, urinary tract infection, skin infections and increasing age)
• Cauda equina syndrome (risk factors include progressive neurological deficit, urinary incontinence or retention, saddle anaesthesia, anal sphincter tone decrease or faecal incontinence and bilateral lower extremity weakness or numbness)
• Compression fractures (risk factors include increasing age, history of trauma, prolonged use of corticosteroids and history of OP)
• Abdominal aortic aneurysm (risk factors include atherosclerotic vascular disease, abdominal pulsating mass, pain at rest and older than 60 years of age)

For many patients with LSS, diagnosis from history and physical examination alone may be difficult; may require advanced imaging to determine and confirm the diagnosis and help to establish a prognosis. Improvements in imaging technology has lead to an increased diagnosis of the condition. Bony findings such as facet joint arthropathy are best seen on CT Soft tissue pathologies such as disc herniation/bulge, ligamentum flavum buckling and/or

hypertrophy or cysts of the facet joint capsule are best seen on MRI

Anatomy

• Lateral canal is an open canal bounded by the VB anteriorly, the pedicle laterally and the superior AP posterolaterally. The nerve root passes through the lateral canal on its way to exiting the IVF
• The IF is bounded by the VB, uncovertebral joints (cervical spine) and IVD anteriorly, the superior facet of the lower vertebra posteriorly and above and below by the pedicles of the adjacent vertebrae
• The nerve root is positioned in the superior aspect of the IF just below the pedicle. The IVF also serves as a passageway for abundant fat, radicular arteries and venous plexus
• As the nerve root lies in the superior aspect of the IVF, it occupies only a small portion of the canal; marked stenosis may therefore not produce nerve root compression or symptoms.

NOTE: For symptoms of sciatica to occur, a degree of nerve root inflammation must be

present. Acute compression does not lead to acute pain in the absence of irritation. When a

non-inflamed nerve is compressed, paraesthesia, reflex abnormalities and motor and sensory losses occur rather than pain

Treatment of LSS

• Treatment is dictated by the pathology, its severity and the patients general condition
• Early spinal cord compression can present with subtle signs and symptoms and therefore a high index of suspicion is required
• All cases of suspected spinal cord compression should be investigated thoroughly and referred to a spinal surgeon (neurosurgeon or orthopaedic surgeon) at an early stage in order to create a more favourable environment promptly via surgical decompression and prevent progressive neurological damage
• Surgery is often required to relieve spinal cord or nerve root compression, but conservative management (analgesia, anti-inflammatories, bed rest or physiotherapy) can be helpful in certain patients especially those with benign disc disease and nerve root compression
• Research has shown that 70-80% of patients with prolapsed lumbar or cervical IVD make spontaneous natural recovery within 2-3 months; surgery can therefore be avoided unless there is severe neurological compromise (e.g. acute cauda equina syndrome from a central lumbar disc)
• Surgery may be required for instability: fixation may lead to a reduction in pain
• Metastatic disease of the spine can be treated with chemotherapy or radiotherapy (effects are not immediate) as a primary treatment or adjunct. Surgery is required when acute compression is present

Surgical approaches:

• Posterior: “fenestration”, laminectomy, hemilaminectomy and laminotomy’ are used to describe the degree of removal of the posterior elements. Most extradural and intradural tumours are approached from the posterior aspect
• Anterior: C1/C2 can be approached via a ‘transoral approach, sub axial spine through a ‘retropharyngeal’ approach, thoracic spine requires thoracotomy, L1-L4/L5 via the retroperitoneal approach and transperitoneal approach for the lumbosacral junction
• Endoscopic: uncommon at present. Exciting area for future development

NB: Prognosis of spinal cord damage (and nerve root damage) is related to pre-operative

function