Innervation of the spinal dura. Myth or reality?

Area of Science:

• Neuroscience
• Anatomy
• Immunology

Background:

• The cranial dura is densely innervated with nerve fibers and mast cells, implicated in vascular headaches and neurogenic inflammation.
• Previous research on spinal dural innervation yielded conflicting and inconclusive results.
• Understanding dural innervation is crucial for headache pathogenesis models.

Purpose of the Study:

• To investigate the pattern of sensory innervation in the rat spinal dura.
• To determine the presence and distribution of mast cells within the rat spinal dura.
• To compare the innervation and mast cell presence between cranial and spinal dura.

Main Methods:

• Immunocytochemistry was employed using antibodies for calcitonin gene-related peptide and substance P to identify sensory nerve fibers.
• Antibodies to serotonin were used to detect mast cells.
• Tissue samples included cranial vault dura, skull base dura, cervical and lumbar dura, and associated ligaments and membranes.

Main Results:

• A dense network of nerve fibers and abundant mast cells were observed in both supratentorial and infratentorial cranial dura.
• The cervical and lumbar spinal dura showed a scarcity of nerve fibers and mast cells.
• Conversely, the posterior longitudinal ligament and peridural membrane exhibited prominent nerve fibers and mast cells.

Conclusions:

• The rat spinal dura is sparsely innervated by calcitonin gene-related peptide- and substance P-positive fibers and contains few mast cells.
• The spinal dura may function primarily as a protective layer and is unlikely to be involved in pain pathogenesis, unlike the cranial dura.
• Further research on primate and human spinal dura is recommended to confirm its relative insensitivity.