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Femoral Neuropathy
KEY FACTS
Terminology
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Synonyms: Femoral neuropathy, femoral mononeuropathy, femoral nerve (FN) palsy
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FN entrapment or injury secondary to direct trauma, compression, stretch injury, or ischemia
Imaging
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Nerve enlargement ± loss of internal fascicular architecture, ↑ T2 hyperintensity
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Injury most common in psoas muscle body, iliopsoas groove, or femoral canal
Top Differential Diagnoses
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Neoplastic femoral nerve infiltration
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Nerve sheath tumor
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Lumbosacral disc syndromes
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Lumbar plexopathy
Pathology
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Reported causes include self-retaining retractor, thigh tourniquet, traumatic injury, heparin anticoagulation (retroperitoneal hematoma), arterial catheterization complication, obstetrical complication, diabetic neuropathy
Clinical Issues
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Acute symptom onset, pain/weakness in FN distribution, diminished/absent knee jerk reflex, thigh muscle atrophy
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Severe back/groin pain (retroperitoneal hematoma)
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Recovery is rule over days → months
Diagnostic Checklist
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Femoral neuropathy is uncommon
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Look carefully for lesion or hematoma in iliopsoas groove or femoral canal
Coronal graphic shows the normal course of the femoral nerve
relative to the psoas muscle
and inguinal ligament
. The femoral nerve produces multiple peripheral branches to the anterior thigh muscles.
relative to the psoas muscle and inguinal ligament . The femoral nerve produces multiple peripheral branches to the anterior thigh muscles.
Coronal STIR MR (femoral neuropathy postsurgical herniorrhaphy) depicts marked enlargement, T2 hyperintensity of the right femoral nerve
, with abrupt transition at the right groin. In this case, the femoral nerve was accidentally ligated during herniorrhaphy.
, with abrupt transition at the right groin. In this case, the femoral nerve was accidentally ligated during herniorrhaphy.
Axial STIR MR in the same patient confirms that the right femoral nerve
in the iliopsoas groove is markedly enlarged with discrete T2 hyperintense fascicles (compared to the normal left femoral nerve
).
in the iliopsoas groove is markedly enlarged with discrete T2 hyperintense fascicles (compared to the normal left femoral nerve ).
Axial CECT (severe hemophilia) depicts large left iliacus
and psoas
hematomas. Femoral neuropathy occurs from compression of the adjacent femoral nerve, which runs along the psoas muscle and iliopsoas groove
. A normal iliopsoas groove is seen on the right
.
and psoas hematomas. Femoral neuropathy occurs from compression of the adjacent femoral nerve, which runs along the psoas muscle and iliopsoas groove . A normal iliopsoas groove is seen on the right .
TERMINOLOGY
Synonyms
-
Femoral mononeuropathy, femoral nerve (FN) palsy
Definitions
-
FN entrapment or injury 2° to direct trauma, compression, stretch injury, or ischemia
IMAGING
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