Lumbosacral plexus root thickening: Establishing normal root dimensions using magnetic resonance neurography

Area of Science:

• Radiology
• Anatomy
• Neurology

Background:

• Disorders of the lumbosacral plexus (LSP) can lead to changes in nerve root diameter.
• Accurate measurement of LSP nerve root dimensions is crucial for diagnosing various neurological conditions.

Purpose of the Study:

• To establish normal lumbosacral plexus (LSP) nerve root dimensions using magnetic resonance neurography (MRN).
• To validate MRN findings against cadaveric measurements.

Main Methods:

• MRN of the LSP was performed on 11 asymptomatic individuals using a 3 T scanner.
• Nerve root dimensions (L2-S1) were measured 5 mm from the dorsal root ganglion (DRG) on coronal IDEAL T2-weighted images.
• Measurements were compared with those from a fresh-frozen cadaver specimen using identical imaging parameters and subsequent anatomical dissection.

Main Results:

• Mean root sizes in patients: L2 (3.12 mm), L3 (4.29 mm), L4 (5.13 mm), L5 (5.29 mm), S1 (5.38 mm).
• High correlation coefficients (0.72 patient vs. cadaver MRN, 0.79 patient vs. dissected cadaver).
• Excellent inter-observer agreement among radiologists (0.73) and anatomists (0.87).

Conclusions:

• Magnetic resonance neurography (MRN) is a reliable method for assessing lumbosacral plexus (LSP) nerve root thickness.
• The established reference values can aid in the diagnosis of LSP disorders.
• Further extensive studies are recommended to confirm these findings.