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.
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Terminology
A laminotomy should not be confused with a laminoplasty in which the laminae are replaced at the end of the procedure.
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:
spinal vascular malformation
A laminoforaminotomy is performed for foraminal decompression.
Contraindications
The following conditions are considered as contraindications of laminotomy and/or laminoforaminotomy:
overt spinal instability
malignant tumors with dural involvement
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:
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postoperative spinal infection
hematomas/blood loss
dural tears with cerebrospinal fluid leakage and pseudomeningoceles
wound dehiscence/wound infection
radiculitis/nerve root damage
laminar fracture
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.