JBR–BTR, 2005, 88: 322-324.

D. Hernalsteen1, G. Cosnard1, A. Peeters2, Th. Duprez1

We report the magnetic resonance (MR) findings in a male patient presenting with a variant chronic idiopathic
demyelinating polyneuropathy (CIDP). He developed a slowly progressive weakness of the right leg associated with
sensory dysfunction. Electrophysiologic studies were pathognomonic for a lower limb demyelinating polyneuropa-
thy based on the slowed conduction velocities of the nerves. MRI showed the two major features of the disease:
marked asymmetric enlargement of the lumbar plexus nerve roots and strong hypersignal of the enlarged roots on
STIR images.

Key-words: Nervous system, diseases.

   A sub-group of hereditary or             the left. A stimulo-detection exami-        major hypertrophy of the right
acquired peripheral demyelinating           nation revealed a reduced com-              nerves roots on the T1-weighted
neuropathies are characterized by a         pound muscle action potential               images (Fig. 1A) and strong hyper-
hypertrophy of the major nervous            (CMAP) mainly after stimulation of          signal intensity within the involved
trunk that can be depicted by MR            the right nervus peroneus profun-           roots on the STIR images (Fig. 1B,
imaging (1-3). The chronic idiopathic       dus, but also of the right nervus tib-      2). Post-contrast images were not
demyelinating         polyneuropathy        ialis. Motor conduction velocity            obtained. The combination of clini-
(CIDP) is the most common form of           (MCV) was reduced in the right              cal history, neurologic examination,
the disorder with relapsing/remit-          nervus peroneus profundus to 28,2           neuro-electrophysiological studies,
ting or progressive proximal and            m/s and in the right nervus tibialis to     and MR imaging yielded the diagno-
distal muscles weakness and with            39,7 m/s (normal values > 40). F-           sis of a focal variant CIDP (Chronic
variable sensory loss as clinical key-      waves for the nervus peroneus pro-          Inflammatory Demyelinating Poly-
features. Cerebrospinal fluid (CSF)         fundus and the H-reflex could not be        neuropathy), which was variant
analysis showing increased protein          elicited at the right side and were         because of the distal topography
level and abnormal slowing of nerve         slightly delayed at the left. The rest      and the significant asymmetry of
conduction velocities with motor            of the motor stimulo-detection              lumbar plexus involvement. Elevat-
conduction blocks on neuro-electro-         exploration was normal, in both             ed levels of proteins in the CSF sup-
physiological studies are main para-        upper and lower limbs. The sensory          ported the diagnosis. As the
clinical features (4-5).                    stimulo-detection was characterized         patient’s clinical status was not sig-
                                            by a reduced sensory conduction             nificantly changed one year later,
Case report                                 velocity of 34 m/s of the right nervus      only physiotherapy was given with-
                                            suralis (normal values > 40 m/s). On        out corticoid therapy nor intra-
   A 64-year-old man presented with         Needle-EMG, denervation signs in            venous immunoglobulin perfusion.
paresthaesias of his right foot and         the right musculus tibialis anterior
toes of two years duration. Symp-           and both musculi gastrocnemii were          Discussion
toms had progressively increased            evidenced. At the left side, the
over time. A few weeks before con-          exploration showed reinnervation               CIDP is an acquired disease of the
sulting, weakness developed in his          signs in the L4, L5 and S1 territory,       peripheral nerves, of putative auto-
right leg with subsequent steppage.         but no active denervation. The con-         immune etiology (1). The major clin-
No radicular pain was present. At           clusion of the electrophysiological         ical feature for a diagnosis of CIDP is
the end of the day, a low back pain         work-up was: “asymmetric polyneu-           a muscle weakness affecting both
mimicking lumbago repeatedly                ropathy with active denervation at          proximal and distal muscles for at
appeared. Neurologic examination            the right side and reinnervation at         least two months, with a tendency
demonstrated stepping on the right                   .
                                            the left” A spinal fluid examination        to symmetric involvement, and a
side, marked amyotrophy of the              showed an elevated level of protein         slowly progressive or remitting/
right anterior tibial muscle, de-           at 93 mg/dl (normal values between          relapsing relapsing course with
creased right Achilles tendon reflex        20 and 55) and the absence of oligo-        time (6). Deep tendon reflexes are
and mild sensory loss of the foot, all      clonal bands at immuno-electro-             either absent or diminished, and
on the right side only. Electro-            phoretic precipitation. An initial MR       sensory symptoms and signs are
diagnostic studies showed signs of          examination excluded mechanical             present. Our patient suffered a low-
asymmetric polyneuropathy of the            radicular compression in pelvis. A          grade form of the disease but exhib-
lower limbs with active denervation         second MRI, focused on the lum-             ited all typical symptoms. CIDP
at the right side and reinnervation at      bosacral plexuses demonstrated              seems to be a quite well circum-
                                                                                        scribed clinical, electrophysiological
                                                                                        and pathological entity with a puta-
  From: Department of 1. Radiology and Medical Imaging and 2. Neurology,
                                                                                        tive auto-immune origin and, subse-
Université catholique de Louvain, Cliniques universitaires Saint-Luc, Bruxelles.        quent efficacy of standard immuno-
  Address for correspondence: Th. Duprez, MD, Department of Radiology and Medical       logic therapies. In the day-to-day
Imaging, Université catholique de Louvain, Cliniques universitaires Saint-Luc, Avenue   practice, the diagnosis may not be
Hippocrate, 10, B-1200-Brussels Belgium.                                                unequivocal because of the hetero-
                             LUMBAR PLEXUS INVOLVEMENT WITH CIDP — HERNALSTEEN et al                                             323

 A                                                                   B
  Fig. 1. – Frontal MR images of the lumbo-sacral plexuses: comparison of T1- and STIR-weighings Unenhanced T1-weighted image
(A) showing hypertrophy of involved roots on the right side (arrows). STIR image (B) in a strictly similar location as previous image
demonstrating excellent fat saturation effect on the background and strong hypersignal intensity within involved right S1 root

                                                                                           geneity of the phenotypes of the dis-
                                                                                           ease (7). Although most patients
                                                                                           have generalised motor and senso-
                                                                                           ry involvement, some may exhibit
                                                                                           regional/partial varieties, with a
                                                                                           prominence of either the sensory or
                                                                                           the motor signs, and with strong
                                                                                           asymmetrical involvement of both
                                                                                           sides. At least, the only clinical
                                                                                           symptom may be radicular pain, or,
                                                                                           in turn, pure radicular motor deficit.
                                                                                           Variant sensory ataxia or multifocal
                                                                                           motor neuropathy involving both
                                                                                           the arms and the legs have been
                                                                                           observed. Our patient had monolat-
                                                                                           eral clinical involvement however
                                                                                           Needle-EMG revealed slight ‘re-
                                                                                           innervation’ signs on the contra-lat-
                                                                                           eral left side. The diagnosis of chron-
                                                                                           ic inflammatory neuropathies relies
                                                                                           on the combination of clinical fea-
                                                                                           tures, electrophysiological patterns,
                                                                                           and of cerebrospinal fluid (CSF)
                                                                                           analyses. But the definite diagnosis
                                                                     Fig. 2. – Reform-     of CIDP is retained after excluding
                                                                  atted frontal STIR       other causes of peripheral polyneu-
                                                                  image clearly de-        ropathy, thereby requiring a com-
                                                                  picts on the same        prehensive work-up excluding
                                                                  view a major in-         exclude systemic
                                                                  volvement of both
                                                                                           diseases like monoclonal gammapa-
                                                                  right L5 and S1
                                                                  roots, and addition-     thy, HIV infection, metabolic heredo-
                                                                  al very slight in-       degenerative disorders, paraneo-
                                                                  volvement of left S1     plastic syndromes, and mono/multi-
                                                                  root.                    focal ischemic neuropathy.
324                                             JBR–BTR, 2005, 88 (6)

   MR examination nowadays play a        the very low contrast-enhancement                polyneuropathy. J Neurol Neurosurg
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order by demonstrating nerve root        almost ruling out the hypothesis of         4.   Latov. Diagnostic of chronic inflam-
thickening (Fig.1A) and intrinsic        a tumoral infiltration, which reached            matory demyelinating polyneuropa-
                                                                                          thy. Neurology, 2002, 59: S2-5.
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                                                                                          Midroni G., Dyck P Chronic inflam-
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