Comparison of 2-limb versus 3-limb electrodiagnostic studies in the evaluation of chronic inflammatory demyelinating polyneuropathy.

INTRODUCTION: European Federation of Neurological Societies/Peripheral Nerve Society electrodiagnostic (EDx) criteria for the definite diagnosis of chronic inflammatory demyelinating polyneuropathy (CIDP) require the presence of demyelinating findings (DF) in at least 2 nerves. Data are lacking, however, regarding the optimal number of nerves to test. METHODS: We retrospectively reviewed EDx data from 53 patients with CIDP and compared the number of DF found on 2- and 3-limb testing. RESULTS: A median of 3 (range 2-5) DF were found on 2-limb testing compared with 5 (range 4-7) DF when 3 limbs were evaluated. Two-limb EDx studies were sufficient to diagnose definite CIDP in 92.3% of typical, 84.2% of asymmetric, and 66.7% of distal phenotypes. Testing a third limb increased diagnostic certainty in 11 patients (20.8%) to definite CIDP. CONCLUSIONS: Three-limb testing may increase diagnostic sensitivity of definite CIDP, especially in patients with atypical phenotypes. Larger prospective studies are needed to better assess the benefit of performing 3-limb EDx studies.

Gender Differences in Skin Biopsy Findings in Small Fiber Neuropathy: A Retrospective Chart Review.

OBJECTIVES: To determine whether there are gender differences in the clinical presentation or skin biopsy measures of nerve fiber density in patients with small fiber neuropathy (SFN). METHODS: Retrospective chart review of subjects with suspected SFN. RESULTS: Of 218 cases (137 women and 81 men) with suspected SFN, 96 (44%), including 63% of the men and 33% of the women (P < 0.05), had low epidermal nerve fiber density (ENFD) or sweat gland nerve fiber density (SGNFD). There were no differences in the clinical presentation between men and women. In those with abnormal findings, low ENFD alone was more frequent in women than men (51.1% vs. 7.8%, P < 0.05), whereas abnormal SGNFD alone was more frequent in men than women (68.6% vs. 11.1%, P < 0.05). Both SGNFD and ENFD were low in 23.5% of men and 33.3% of women. Skin biopsy findings were independent of clinical presentation or etiology. CONCLUSIONS: The clinical presentation of SFN is similar in men and women. In skin biopsy studies, low ENFD is more common in women and low SGNFD in men.

Abnormal Nutritional Factors in Patients Evaluated at a Neuropathy Center.

Abnormal concentrations of nutritional factors were found in 24.1% of 187 patients with neuropathy who were newly seen at our academic neuropathy referral center over a 1-year period. All patients presented with sensory axonal or small fiber neuropathy. In 7.3%, they were present in association with at least one other identifiable cause for neuropathy. Elevated levels of pyridoxal phosphate or mercury occurred more frequently than deficiencies in vitamins B1, B12, or B6. The nutritional abnormalities are amenable to correction by dietary intervention.

Necrosis, apoptosis and hybrid death in the cortex and thalamus after barrel cortex ischemia in rats.

Focal ischemia in the cerebral cortex results in acute and delayed cell death in the ischemic cortex and non-ischemic thalamus. We examined the hypothesis that neurons in ischemic and non-ischemic regions died from different mechanisms; specifically, we tested whether a mixed form of cell death containing both necrotic and apoptotic changes could be identified in individual cells. Focal barrel cortex ischemia in rats was induced by occlusion of small branches of the middle cerebral artery (MCA) corresponding to the barrel cortex, local blood flow was measured by quantitative autoradiography. Cell death was visualized by 2,3,5-triphenyltetrazolium chloride (TTC) staining, hematoxylin-eosin (H&E) staining, the terminal deoxyribonucleotidyl transferase-mediated dUTP nick end labeling (TUNEL), and caspase-3 staining 1 to 10 days after the ischemia. Electron microscopy was used for ultrastructural examination. Cell death occurred in the ipsilateral cortex 24 h after ischemia, followed by selective neuronal death in the ventrobasal (VB) thalamus 3 days later. TUNEL positive neurons were found in these two regions, but with striking morphological differences, designated as type I and type II TUNEL positive cells. The type I TUNEL positive cells in the ischemic cortex underwent necrotic changes. The type II TUNEL positive cells in the thalamus and the cortex penumbra region represented a hybrid death, featured by concurrent apoptotic and necrotic alterations in individual cells, including marked caspase-3 activation, nuclear condensation/fragmentation, but with swollen cytoplasm, damaged organelles and deteriorated membranes. Cell death in the thalamus and the cortex penumbra were attenuated by delayed administration of the caspase inhibitor benzyloxycarbonyl-Val-Ala-Asp fluoromethylketone (Z-VAD-FMK). Our data suggest that TUNEL staining should be evaluated with morphological changes, the hybrid death but not typical apoptosis occurs in the penumbra region and non-ischemic thalamus after cerebral ischemia.

Prolongation of the tibialis anterior CMAP duration in chronic inflammatory demyelinating polyneuropathy.

OBJECTIVE: To assess the duration of the distal compound muscle action potential (dCMAP) recording from the tibialis anterior (TA) as a supportive electrodiagnostic feature in chronic inflammatory demyelinating polyneuropathy (CIDP). METHODS: We performed peroneal motor conduction studies with recording from the TA in 35 CIDP patients, 30 normal controls, and 21 disease controls. The normal cut-off for the TA dCMAP duration was determined to be 14 ms. RESULTS: Prolonged TA dCMAP durations were detected in 34% of CIDP patients (12/35) and in 33% (2/6) of patients in whom only one demyelinating lesion was identified by conventional motor conduction studies. Prolonged TA dCMAP durations were present in 28% (5/18) of patients with normal duration dCMAPs recorded from the abductor hallucis (AH) and in 42% (5/12) of patients with normal duration dCMAPs recorded from the extensor digitorum brevis (EDB). In patients with AH or EDB dCMAP amplitudes <1 mV, TA dCMAP durations were prolonged in 28% and 23% of patients, respectively. CONCLUSIONS: Determination of TA dCMAP duration appears to be useful for detecting demyelination in CIDP, especially when there is significant coexisting axon loss. SIGNIFICANCE: In patients with potential CIDP and limited electrodiagnostic abnormalities by routine studies, the finding of additional demyelinating findings, such as increased TA dCMAP duration, could allow for improved diagnostic sensitivity.