Foraminal stenosis: what it is, symptoms and treatment

What is foraminal stenosis?

Between every two vertebrae there is a bony opening called the neural foramen or intervertebral foramen. The nerve root that connects the spinal cord to the rest of the body exits through it. Foraminal stenosis consists of the narrowing of that foramen, which reduces the space available for the nerve root and ends up compressing it.

This compression irritates the nerve and triggers a picture of radiculopathy: pain radiating along the nerve's course, together with tingling, numbness and, in advanced stages, loss of strength. It can occur in the cervical, thoracic or lumbar spine, with the cervical and lumbar regions being the most clinically relevant.

Difference from spinal canal stenosis

Although often confused, they are distinct conditions:

• Spinal canal stenosis (central): narrows the central spinal canal, through which the spinal cord (at cervical and thoracic levels) or the cauda equina (at lumbar level) passes. It typically causes bilateral symptoms or neurogenic claudication (leg pain on walking that improves on sitting).
• Foraminal stenosis (lateral): narrows the foramen through which a specific nerve root exits. It typically produces symptoms of a single nerve root, in one arm or one leg.

Both can coexist in the same patient, and distinguishing them through imaging and examination determines the therapeutic strategy.

Causes of foraminal stenosis

Most cases are degenerative and develop over the years. The most common causes are:

• Facet arthrosis: joint wear generates osteophytes (bony spurs) that invade the foramen.
• Disc herniation: displaced disc material, especially foraminal or extra-foraminal herniation, occupies the root's space.
• Loss of disc height: as the disc dehydrates, the vertebrae approximate and the foramen closes vertically.
• Thickening of the ligamentum flavum.
• Spondylolisthesis: slippage of one vertebra over another deforms the foramen and may cause instability.
• Trauma and fractures causing malalignment.

Symptoms: cervical and lumbar radiculopathy

Cervical foraminal stenosis

When a cervical nerve root is affected, pain starts in the neck and descends through the shoulder and arm to the hand, following a specific pattern. It is accompanied by tingling or numbness in specific fingers, weakness for certain movements and, sometimes, a sense of loss of dexterity. Some neck positions worsen the pain.

Lumbar foraminal stenosis

Involvement of a lumbar nerve root causes sciatica: pain that travels through the buttock and down the back or side of the leg, sometimes to the foot. Tingling, leg weakness and worsening on standing or walking are common, with relief on leaning forward or sitting.

Diagnosis

Diagnosis is clinical and confirmed with complementary tests:

• MRI: the reference test. Shows the compressed root, discs and soft tissues in detail.
• CT: defines the bony component (osteophytes, actual foramen calibre) and is useful when MRI is contraindicated.
• Electromyography (EMG): identifies which nerve root is affected and the degree of compromise, and helps exclude other causes of symptoms.

Correlation between imaging and neurological examination is essential: treating the correct nerve root avoids unnecessary surgery.

Conservative treatment

Most patients improve without surgery. Conservative management includes:

• Physiotherapy and therapeutic exercise aimed at decompressing the root and stabilising the spine.
• Analgesia and anti-inflammatory drugs, together with pain neuromodulators when there is a neuropathic component.
• Image-guided epidural or foraminal injections, which reduce inflammation around the root in selected cases.
• Postural habit correction and workplace ergonomics improvement.

Surgical treatment

Surgery is considered when disabling pain persists despite well-conducted conservative treatment, or in the face of progressive neurological deficit (loss of strength). The main options are:

• Foraminotomy: widening of the foramen to decompress the nerve root. It is the technique of choice for isolated foraminal stenosis.
• Minimally invasive and endoscopic decompression: through millimetre-sized incisions, the bone or disc compressing the root is removed, preserving musculature and accelerating recovery.
• Spinal fusion: reserved for cases with associated instability, such as spondylolisthesis, to stabilise the treated segment.

At Brain & Spine Barcelona we always prioritise the least invasive technique that resolves each patient's problem.

Recovery

With minimally invasive and endoscopic techniques many patients are discharged the same day or the following day and resume light activity within a few weeks. When a fusion is performed, consolidation timelines are longer. In all cases, a guided rehabilitation programme improves functional outcome and reduces the risk of recurrence.