Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP): MRI

Case Report

24 yrs male presents for MRI of cervical & dorsal spine with H/O neck pain, right upper limb pain, back pain & imbalance in walking of long duration.

MRI findings

Gross thickening with STIR hyperintense signal  in cervical nerve roots in foraminal & extraforaminal segments with severe near symmetric involvement of bilateral brachial plexus in entire extent upto divisions & cords without any focal nodularity in the thickened nerve roots & with intact surrounding fat planes. Thickening with increased signal to mild extent also seen in all the dorsal nerve roots & intercostal nerves bilaterally. Limted sagittal sections of LS spine show significant thickening of lumbar & sacral nerve roots in foraminal & extraforaminal  segments without thickening of nerve roots of cauda equina. Spinal cord is unremarkable without any focal lesion or any extrinsic compression. Findings are not specific to etiology, possibly suggestive of hypertrophic polyneuropathy like chronic inflammatory demyelinating polyradiculoneuropathy (CIDP)

Discussion by Dr MGK Murthy, Dr GA Prasad

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is characterized clinically by a progressive or relapsing course of many months to years of symptoms similar to compressive myelopathy.

Etiology 

Remains unknown, but T-cell activation in nerves plays an important role in the pathogenesis of CIDP & antigens in Schwann cells have been identified.

Pathologically

CIDP is characterized by mononuclear cell infiltrates, edema, segmental demyelination, and remyelination & "onion bulb formation" which describes enlarged fascicles with increased endoneural connective tissues in which many myelinated fibers are surrounded by concentrically arranged  Schwann cells  that affects both nerve roots and peripheral nerves leading to nerve hyprtrophy.

MRI 

Hypertrophy and abnormal enhancement of the cauda equina and lumbar spinal roots are seen. Involvement of cervical roots and the brachial plexus are rare & involvement of

intercostal nerves is also rare. Increased T2 signal intensity and the variable contrast

enhancement of roots and nerve trunks reflect increased water content within the nerve fascicles and breakdown of the blood–nerve barrier, respectively. Gadolinium enhancement possibly suggests active disease.

An elevated protein and low cell count in CSF sample, slowing/ block / prolonged distal latencies, and absence of waves or prolonged minimum f-wave latencies in electrophysiological

studies of nerve conduction suggest CIDP.

Differential diagnosis of nerve root hypertrophy–

1.      Hereditary motor and sensory neuropathies (HMSN) – which are a heterogeneous group of genetically determined peripheral neuropathies characterized by symmetrical and predominately distal motor and sensory disturbances and a slowly progressive course. Charcot-Marie-Tooth and Déjèrine-Sottas disease are the disorders most characteristically associated with marked thickening of peripheral nerves (hypertrophic neuropathies).

-        Dejerine-Sottas disease (also known as hereditary motor and sensory neuropathy type III or hypertrophic interstitial polyneuritis) – predominantly causes enlarged cauda equina nerve roots & cranial nerves.

-        Charcot-Marie-Tooth disease – usually shows diffusely enlarged cauda equina, nerve roots, and ganglia.

Diagnosis is founded on familial history, clinical-laboratory data, electromyography and nerve conduction studies, sural nerve biopsy, and molecular genetic studies.

2.      Neurofibromatosis.

3.      Guillian-Barre syndrome -   acute and rapidly progressive inflammatory demyelinating polyneuropathy &  diagnosis is usually established on the basis of symptoms and signs,  cerebrospinal fluid findings and electrophysiologic criteria. MRI shows  marked enhancement of the thickened nerve roots in the conus medullaris and cauda equine with or without abnormalities on precontrast images.

4.      Neoplastic lesions like lymphoma / leukemia / meningeal carcinomatosis.

5.      Sarcoidosis / Amyloidosis.

6.      CMV polyradiculopathy in patients with AIDS / Lyme's disease.

Biopsy of the involved peripheral nerve, usually sural nerve may help in the diagnosis.

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