Neuropathy in ARSACS is demyelinating but without typical nerve enlargement in nerve ultrasound

BACKGROUND

To specify peripheral nerve affection in autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS) by correlating high-resolution nerve ultrasound and nerve conduction studies.

METHODS

We assessed a cohort of 11 ARSACS patients with standardized nerve conduction studies and high-resolution ultrasound of peripheral nerves and compared nerve ultrasound findings to a healthy control group matched for age, sex, size and weight.

RESULTS

Mean age of patients was 39.0 (± 14.1) years and disease duration at assessment 30.6 (± 12.5) years. All patients presented with a spasticity, ataxia and peripheral neuropathy. Neuropathy appeared to be primarily demyelinating in 9/11 cases and was not classifiable in 2/11 cases due to not evocable potentials. Nerve ultrasound revealed a normal ultrasound pattern sum score (UPSS) in each ARSACS patient and no significant nerve enlargement compared to the control group.

CONCLUSIONS

Peripheral neuropathy in ARSACS showed primarily demyelinating rather than axonal characteristics and presented without nerve enlargement. As demyelinating neuropathies do commonly present enlarged nerves we recommend further genetic testing of the SACS gene in patients who present with this combination of demyelinating neuropathy without nerve enlargement. ARSACS cases that initially presented only with neuropathy without spasticity or ataxia and therefore were misdiagnosed as Charcot-Marie-Tooth disease are supporting this suggestion.

[Interdisciplinary networks in diseases of peripheral nerves-Exemplified by the Tübingen nerve team]

BACKGROUND

Nerve damage can be autoimmune inflammatory, metabolic or traumatic, among others, and can be difficult to differentiate.

OBJECTIVE

What are the advantages of interdisciplinary networks and how do they work?

MATERIAL AND METHOD

Field report with case presentation from the University Hospital Tübingen in cooperation with the BG Accident Clinic Tübingen.

CONCLUSION

Interdisciplinary networks improve the care of our patients and also serve as regular multidisciplinary continuing education.

Continuous intraoperative neuromonitoring (cIONM) in head and neck surgery-a review

Although the history of intraoperative neuromonitoring (IONM) dates back to the 19th century, the method did not evolve further than the mere differentiation of nerves until recently. Only the development of continuous IONM (cIONM) has allowed for non-stop analysis of excitation amplitude and latency during surgical procedures, which is nowadays integrated into the software of almost all commercially available neuromonitoring devices. The objective of cIONM is real-time monitoring of nerve status in order to recognize and prevent impending nerve injury and predict postoperative nerve function. Despite some drawbacks such as false-positive/negative alarms, technical artefacts, and rare adverse effects, cIONM remains a good instrument which is still under development. Active (acIONM) and passive (pcIONM) methods of cIONM are described in literature. The main fields of cIONM implementation are currently thyroid surgery (in which the vagal nerve is continuously stimulated) and surgery to the cerebellopontine angle (in which the facial nerve is either continuously stimulated or the discharge signal of the nerve is analyzed via pcIONM). In the latter surgery, continuous monitoring of the cochlear nerve is also established.

Peripheral Nerve Imaging Aids in the Diagnosis of Immune-Mediated Neuropathies-A Case Series

Background: Diagnosis of immune-mediated neuropathies and their differentiation from amyotrophic lateral sclerosis (ALS) can be challenging, especially at early disease stages. Accurate diagnosis is, however, important due to the different prognosis and available treatment options. We present one patient with a left-sided dorsal flexor paresis and initial suspicion of ALS and another with multifocal sensory deficits. In both, peripheral nerve imaging was the key for diagnosis. Methods: We performed high-resolution nerve ultrasound (HRUS) and 7T or 3T magnetic resonance neurography (MRN). Results: In both patients, HRUS revealed mild to severe, segmental or inhomogeneous, nerve enlargement at multiple sites, as well as an area increase of isolated fascicles. MRN depicted T2 hyperintense nerves with additional contrast-enhancement. Discussion: Peripheral nerve imaging was compatible with the respective diagnosis of an immune-mediated neuropathy, i.e., multifocal motor neuropathy (MMN) in patient 1 and multifocal acquired demyelinating sensory and motor neuropathy (MADSAM) in patient 2. Peripheral nerve imaging, especially HRUS, should play an important role in the diagnostic work-up for immune-mediated neuropathies and their differentiation from ALS.

Normative Observational Nerve Ultrasound Values in School-Age Children and Adolescents and Their Application to Hereditary Neuropathies

Backgrounds: We have aimed to establish nerve ultrasound reference data in 8 to 17-year-old children and adolescents and to compare those data to younger children, adults, and age-matched children with polyneuropathies.

Methods: High-resolution ultrasounds of the nerves were performed in 117 healthy children and adolescents at 20 predefined landmarks in the neck and the extremities of both sides. Mean values, side-to-side differences and intraneural ratios, as well as upper limits have been calculated. In a second step, a comparison between 25 children and adolescents of the same age range with proven hereditary and acquired neuropathies and lysosomal storage diseases has been carried out.

Results: Nerve growth correlates significantly with age and reaches adult values at the age of around 15 years. The influence of body mass index and gender is negligible at most segments. By the use of age-specific upper limits, nerve enlargement could be seen in distinct types of neuropathies, particularly in demyelinating hereditary and inflammatory types, which is comparable to findings in adults, but also in rare lysosomal storage diseases.

Conclusion: Nerve size correlates with age during childhood and reaches a climax in younger adults. Age-matched reference data are inevitable to differ between hypertrophic and non-hypertrophic nerve damage, e.g., in neuropathies.

Role of high-resolution ultrasound in detection and monitoring of peripheral nerve tumor burden in neurofibromatosis in children

PURPOSE

Peripheral nerve sheath tumors are hallmark findings in neurofibromatosis types 1 and 2. With increasing size, they typically lead to neurological symptoms, and NF1 patients have a lifetime risk of 8-13% for developing malignant peripheral nerve sheath tumors. Medical imaging is therefore highly needed for early detection and exact localization of symptomatic or potentially malignant tumors. This review will give an overview of the ultrasound characteristics of peripheral nerve sheath tumors and findings in patients with neurofibromatosis types 1 and 2.

METHODS

A systematic search of electronic databases, reference lists, and unpublished literature was conducted including the keywords "schwannoma," "neurofibroma," "neurofibromatosis," "benign and malignant peripheral nerve sheath tumor."

RESULTS

The high-resolution allows a clear analysis of tumor echotexture, definition of margins, and the relation to the parent nerve. The use of color duplex/Doppler and contrast agent adds valuable information for the differentiation of benign and malignant tumors.

CONCLUSION

High-resolution ultrasound is a well-established, non-invasive, and easily repeatable first-line tool in diagnostic procedures of soft tissue tumors.

[The infracochlear approach for diagnostic petrous apicotomy]

Diagnostic and therapeutic approaches to the petrous apex involve sub-/transtemporal, retrosigmoidal, infratemporal and-lesser invasive-e. g. infracochlear, infralabyrinthine or under favourable anatomic conditions, transsphenoidal surgical pathways. For diagnostic purposes, minimally invasive approaches should be preferred due to their lesser morbidity. This article illustrates the infracochlear approach to the petrous apex in the case of a diagnostic indication in a patient with an incidental, asymptomatic tumorous lesion of the right petrous apex with bony erosion. After the bone of the floor of the ear canal and the hypotympanum was removed, the carotid artery and the jugular bulb were identified using a diamond burr. The route to the petrous apex is triangled by the cochlea superiorly, the jugular bulb posteriorly, and the carotid artery anteriorly. After opening the petrous apex lesion, biopsies were taken. The defect in the floor of the ear canal and the hypotympanum was reconstructed with cartilage and temporalis fascia. The patient recovered quickly from surgery without vertigo or hearing loss. Histological evaluation showed a chondrosarcoma. The patient opted for primary radiation therapy (C12, 63 Gy). The infracochlear approach is minimally invasive and can offer access to the petrous apex with minimal morbidity. The pathway, however, is narrow and deep and bounded by the jugular bulb and the carotid artery. The available space can be estimated from preoperative CT scans and, if possible, with 3D reconstructions. Navigation can additionally enhance safety.

Pressure-Induced Order–Disorder Phase Transition of Spinel Single Crystals

The present study deals with single-crystal structure investigations by means of X-ray scattering of a pressure-induced phase transition of Mg0.4Al2.4O4. The compressibility of the substance is very small, whereas the structural changes are surprisingly high. A non-identified high-pressure phase turns out to be reversible considering the existence of a spinel single crystal, but not reversible with regard to the ordering of the cations in the oxygen framework. The pressure-induced disordering of the cations is preserved on abrupt pressure decrease and can be detected in a recovered specimen.

High-Pressure Study of h.c.p.-Argon

Argon, used as pressure medium in high-pressure experiments, crystallizes in a hexagonal close-packed structure when the argon is loaded cryogenically in the diamond anvil cell. The behaviour under pressure reveals elastic properties comparable to that of f.c.c.- argon (f.c.c. = face-centred cubic). The bulk modulus is 6.5 (1.3) GPa. The initially good quality of the individual crystals suffers strongly under pressure increase. Heating the cell to 393 K at 8.5 GPa recreates the crystal structure, accompanied by a pressure decrease of more than 1 GPa.