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Dorsal root ganglion of spinal nerve

The dorsal root ganglion (DRG), also known as the spinal ganglion, is a cluster of sensory neuronal cell bodies located on the dorsal root of each spinal nerve. It contains the cell bodies of primary sensory neurons responsible for transmitting sensory information such as touch, pain, temperature, and proprioception from the periphery to the spinal cord.

The DRG is an essential component of the peripheral nervous system and is clinically important in conditions such as radiculopathy, neuropathic pain syndromes, and nerve compression disorders.

Synonyms

  • Spinal ganglion

  • Posterior root ganglion

  • Sensory root ganglion

Origin, Location, and Structure

  • Origin: Formed during embryological development from neural crest cells that migrate to the dorsal root of the spinal nerve

  • Location:

    • Situated within or just lateral to the intervertebral foramen, on the dorsal root of the spinal nerve

    • Present at every spinal nerve level except the first cervical (C1) nerve

  • Structure:

    • Contains pseudounipolar neurons with cell bodies that transmit sensory signals from peripheral receptors to the spinal cord

    • Surrounded by satellite glial cells and enclosed within a connective tissue capsule

    • Connected proximally to the dorsal horn of the spinal cord and distally to the mixed spinal nerve

Relations

  • Proximal: Dorsal horn of spinal cord via dorsal root fibers

  • Distal: Mixed spinal nerve before splitting into dorsal and ventral rami

  • Surroundings: Enclosed within the intervertebral foramen, adjacent to vertebral bone, intervertebral disc, and spinal vessels

Function

  • Acts as the primary sensory relay station of the spinal nerve

  • Transmits afferent signals:

    • Touch, pressure, pain, temperature, vibration, and proprioception

  • Houses pseudounipolar neuron cell bodies for rapid conduction of sensory signals

  • Critical role in neuropathic pain when abnormal discharges occur from DRG neurons

Clinical Significance

  • Radiculopathy: Compression by herniated discs, spondylosis, or foraminal stenosis

  • Neuropathic pain: DRG hyperexcitability contributes to chronic pain syndromes

  • Tumors: May be enlarged in schwannomas or neurofibromas

  • Target in therapy: Site for dorsal root ganglion stimulation in refractory neuropathic pain

  • Imaging relevance: Identification on MRI helps localize spinal pathology and guide interventions

MRI Appearance

T1-weighted images:

  • DRG appears as an intermediate signal oval/round structure in the intervertebral foramen

  • Surrounded by bright epidural and perineural fat

T2-weighted images:

  • Shows intermediate to mildly hyperintense signal compared to muscle

  • Pathology (inflammation, edema, tumor) appears bright

STIR (Short Tau Inversion Recovery):

  • Normal DRG: low signal

  • Pathology (neuritis, edema, tumor infiltration): bright hyperintensity

T1 Fat-Sat Post-Contrast:

  • Normal DRG: mild or no enhancement

  • Pathology: marked or heterogeneous enhancement in neuritis, tumors, or infection

3D T2 SPACE / CISS:

  • DRG shows intermediate to mildly hyperintense signal compared to muscle

  • Surrounded by bright CSF or fat in the neural foramen, providing excellent delineation

  • Ideal for evaluating foraminal stenosis, nerve root compression, or small tumors

CT Appearance

Non-Contrast CT:

  • DRG not directly visible; inferred as soft tissue density within intervertebral foramen

  • Surrounding fat provides contrast

  • Foraminal narrowing or bony encroachment can affect the DRG

Post-Contrast CT:

  • DRG itself does not normally enhance significantly

  • Pathological conditions (tumors, inflammatory infiltration) may show focal enhancing masses in the neural foramen

  • CT myelography may indirectly outline the nerve root and ganglion

MRI image

Dorsal root ganglion of spinal nerve MRI axial anatomy image-img-00000-00000

MRI image

Dorsal root ganglion of spinal nerve MRI sagittal anatomy image-img-00000-00000