Laminotomy

A laminotomy is a spinal decompression procedure with partial removal of the vertebral arch usually at its base. Laminotomies might be combined with other spinal procedures such as discectomy or spinal fusion procedures. If a laminotomy is combined with a foraminotomy, then the procedure is called a laminoforaminotomy.

Terminology

Synonymous terms for a laminotomy include laminoplasty, replacement laminotomy, osteoplastic laminotomy, non-expansive laminotomy or laminoplasty, open-door laminoplasty and en-bloc laminoplasty ¹.

Indications

Laminotomy is a common approach to the spinal canal in clinical settings where a bony decompression of the spinal canal is not the target of spinal surgery and includes the following indications ^1-3:

• herniated disc
• spinal vascular malformation
• non-osseous primary spinal tumors
  • astrocytoma
  • spinal cavernoma
  • ependymoma
  • schwannoma
  • spinal lipoma
• arachnoid cyst
• syringomyelia
• epidural hematoma

A laminoforaminotomy is performed for foraminal decompression.

Contraindications

The following conditions are considered as contraindications of laminotomy and/or laminoforaminotomy:

• bony spinal canal stenosis
• overt spinal instability
• bony lesions
• malignant tumors with dural involvement
• spinal infections

Procedure

The procedure and technique of laminotomy depend on location and indication. It can be unilateral or bilateral as hemilaminotomy with or without undercutting, central laminotomy or split laminotomy ^1,2. It can be performed on multiple levels. Microscopic and endoscopic techniques exist ^1,4.

A rough overview and example of a surgical procedure include the following steps ^1,2:

Opening

• dissection of the paraspinal muscles away from the spinous processes and laminae
• incision of the supraspinous and interspinous ligaments at the most cranial and caudal levels
• caudocranial osteotomy of the lamina about halfway between the spinous process and facet joint either unilateral with or without undercutting, rarely bilateral or as a split procedure

Closure

• repositioning of the osteoligamentous flap and fixation
• suturing of the supraspinous ligament and approximation of the paraspinal muscles
• suturing of the fascia, subcutaneous tissue layer and skin

Complications

Complications of laminotomy or laminoforaminotomy include the following ^1,3,5:

• postoperative spinal infection
  • epidural abscess
  • spondylodiscitis
  • vertebral osteomyelitis
• hematomas/blood loss
• dural tears with cerebrospinal fluid leakage and pseudomeningoceles
• wound dehiscence/wound infection
• arachnoiditis
• radiculitis/nerve root damage
• laminar fracture
• failed back or neck surgery syndrome
• textiloma

Radiographic features

Plain radiograph

A laminotomy can be seen on AP radiographs of the cervical, thoracic or lumbar spine like a small defect on the inferior aspect of the posterior vertebral lamina.

CT

CT can detect and characterize the location of implants as well as complications and might assess the success of decompression. 

MRI

MRI can be used to evaluate the success of decompression and show a fibrous scar at the level of the cut of the supraspinous and interspinous ligaments and any signs of epidural fibrosis ¹.

Signal characteristics

• T1: hypointense
• T2: hyperintense
• T1C+(Gd): enhancement

Radiology report

The postoperative radiological report should include a description of the following features:

• fibrous scar tissue
• level of laminotomy
• complications

Outcomes

A laminotomy is considered as generally less invasive than a laminectomy or hemilaminectomy with less risk of tissue damage ¹. It is also associated with a shorter procedure time and lower risk of blood loss, epidural fibrosis or scar formation and spinal cord trauma after surgery. It is not suitable in the setting of bilateral bony stenosis with cord compression or severe facet joint hypertrophy ¹.