Chronic immune sensory polyradiculopathy (CISP): First juvenile case description

In its typical presentation, chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) occurs more often in old males as a progressive/recurrent motor and sensory nerve dysfunction with tendon areflexia. However, CIDP has also atypical clinical presentations, including pure sensory neuropathies, among which chronic immune sensory polyradiculopathy (CISP) accounts for only 0.5% of all CIDP, with no juvenile cases reported as yet. A 17-year-old girl presented for a progressive sensory ataxia and hands clumsiness. Diffuse tendon areflexia and hypokinaesthesia were observed. Motor and sensory nerve conduction studies were normal. F-waves were normal in median nerves and elongated in tibial nerves. H-reflex and somatosensory evoked potentials (SSEP) were absent. CSF normal cellularity with hyperproteinorrachia was found. Paraneoplastic, metabolic, and paraproteinemic neuropathies were excluded. A diagnosis of CISP has been made based on the presence of pure sensory symptoms in a polyneuropathic distribution, normal peripheral nerve conduction studies, and two supportive criteria (SSEP and CSF). Our paper describes the first CISP case in the pediatric age. We confirm SSEP and CSF as useful complementary tests for this diagnosis also at this age and suggest that clinicians should consider CISP in the spectrum of sporadic sensory ataxias of the pediatric age. We also suggest that in the presence of normal F-wave and peripheral motor nerve conduction, an absent H-reflex can further substantiate SSEPs in the diagnosis of CISP. Intravenous immunoglobulins were rapidly effective and safe.

The electrodiagnosis of Guillain-Barré syndrome subtypes: Where do we stand?

It is controversial as to whether the electrophysiological Guillain-Barré syndrome (GBS) subtypes can be diagnosed on the basis of a single study and which criteria sets and cut-offs should be used. Serial electrophysiologic studies have shown that a significant number of patients changed electrodiagnostic subtype largely because of the recognition of reversible conduction failure as a possible evidence of axonal pathology. However, other reports concluded that electrodiagnosis can be made by a single study, the subtypes depending on the characteristic of the criteria set applied. Such divergent views, although explicable by the different methodology employed, can be confusing in the everyday practice. We argue that the pathophysiology of GBS is dynamic and that serial studies allow a more accurate diagnosis of subtypes. A second study, although not always practicable, is recommended in patients showing no clear demyelinating features, low amplitude distal compound muscle action potentials or conduction block without temporal dispersion. For practical purposes, we propose that at a first study Uncini's or Rajabally's criteria sets can be employed for an indicative subtype diagnosis. Finally, although the GBS subtype diagnosis has currently no impact on treatment, we believe that is important for understanding the underlying pathophysiology and prognostication.

Optimizing the electrodiagnostic accuracy in Guillain-Barré syndrome subtypes: Criteria sets and sparse linear discriminant analysis

OBJECTIVE

To optimize the electrodiagnosis of Guillain-Barré syndrome (GBS) subtypes at first study.

METHODS

The reference electrodiagnosis was obtained in 53 demyelinating and 45 axonal GBS patients on the basis of two serial studies and results of anti-ganglioside antibodies assay. We retrospectively employed sparse linear discriminant analysis (LDA), two existing electrodiagnostic criteria sets (Hadden et al., 1998; Rajabally et al., 2015) and one we propose that additionally evaluates duration of motor responses, sural sparing pattern and defines reversible conduction failure (RCF) in motor and sensory nerves at second study.

RESULTS

At first study the misclassification error rates, compared to reference diagnoses, were: 15.3% for sparse LDA, 30% for our criteria, 45% for Rajabally's and 48% for Hadden's. Sparse LDA identified seven most powerful electrophysiological variables differentiating demyelinating and axonal subtypes and assigned to each patient the diagnostic probability of belonging to either subtype. At second study 46.6% of axonal GBS patients showed RCF in two motor and 8.8% in two sensory nerves.

CONCLUSIONS

Based on a single study, sparse LDA showed the highest diagnostic accuracy. RCF is present in a considerable percentage of axonal patients.

SIGNIFICANCE

Sparse LDA, a supervised statistical method of classification, should be introduced in the electrodiagnostic practice.