Consider differentials before diagnosing COVID-19 associated polyradiculitis

Evidence is accumulating that SARS-CoV-2 infections and SARS-CoV-2 vaccinations can induce Guillain-Barre syndrome (GBS). More than 400 GBS cases after SARS-CoV-2 infection respectively vaccination have been reported as per the end of 2021. GBS is usually diagnosed according to the Brighton criteria, but also the Besta criteria or Hadden criteria are applied. The diagnosis can be supported by MRI with contrast medium of the cranial or spinal nerves showing enhancing nerve roots. As GBS can be complicated by autonomic dysfunction such as pupillary abnormalities, salivatory dysfunction, reduced heart rate variability, bowel disturbance (constipation, diarrhea), urinary hesitancy, urinary retention, or impotence, it is crucial to investigate GBS patients for autonomic involvement. Before diagnosing GBS various differentials need to be excluded, including neuropathy as a side effect of the anti-SARS-CoV-2 medication, critical ill neuropathy in COVID-19 patients treated on the ICU, and compression neuropathy in COVID-19 patients requiring long-term ventilation.

Brainstem and Cranial Nerves: Overview and Medulla

This chapter reviews the anatomy of the brainstem and cranial nerves and important structures at the level of the medulla. The next 3 chapters discuss important structures at the level of the pons, important structures at the level of the midbrain, and pathways that traverse the entire brainstem. The 12 pairs of cranial nerves (numbered I-XII), like spinal nerves, contain sensory or motor fibers or a combination of fiber types. These fibers are classified according to their embryologic origin or common structural and functional characteristics.

Prof. G. Guillain. Neurologes neurolog'iques. 3-я серия. Стр. 453, рис. 119 Masson etemp-edema. Ц. фр. 70.

In this volume, prof. Guillain collected the last works of his supervisor. Salpetriera clinics; he divided them into 7 sections: cerebral tumors, pathology of the brain, pathology of the legs of the pons, the medulla oblongata, the cerebellum, pathology of the spinal cord, pathology of the cranial and spinal nerves, muscle atrophy and other, and then a chapter on the history of neurology, dedicated to the works of the famous Boulogne neuropathologist Duchenne.

Relation of the lumbosacral trunk to the sacro-iliac joint

This study aims to evaluate the relation between the lumbosacral trunk (LT) and the sacro-iliac joint (SIJ). In forty anatomic specimens (hemipelves) a classical antero-lateral approach to the SIJ was performed. The SIJ was marked at the linea terminalis (reference point A). Reference point B was situated at the upper edge of the interosseous sacro-iliac ligament. The length of the SIJ (distance A to B) and the distance between point A and the ventral branch of the fourth (L4) and fifth (L5) lumbar spinal nerves at the linea terminalis were measured. The SIJ had a mean length of 58.0 mm. The ventral branch of L5 was located closer to the SIJ in very long SIJs (mean length: ≥ 6.5 cm; mean distance: 9.8 mm) compared to very short joints (≤ 5 mm; mean distance: 11.3 mm). For the ventral branch of L4, very long SIJs had a mean distance of 7 mm and very short joints an average distance of 9.7 mm between point A and the nerve branch. A safe zone of approximately 1 cm to 2 cm (anterior to posterior) is present on the sacral surface (lateral to medial) for safe fixation of plates during anterior plate stabilization of the SIJ. Pelves with a shorter dorsoventral diameter of the most superior part of the SIJ apparently give more space for inserting plates.

A significant association between C5 nerve sheath tumors and new postoperative weakness

OBJECTIVE The objective of this study was to determine if patients with nerve sheath tumors affecting the C5 spinal nerve are at greater risk for postoperative weakness than those with similar tumors affecting other spinal nerves contributing to the brachial plexus. METHODS A retrospective chart review (1998–2020)identified patients with pathologically confirmed schwannomas or neurofibromas from the C5 to T1 nerves. Patients with plexiform nerve sheath tumors, tumors involving more than 1 nerve, and malignant peripheral nerve sheath tumors were excluded. Collected variables included basic demographics, tumor dimensions, its location relative to the dura, involved nerve level, surgical approach, extent of resection, presenting symptoms, postoperative neurological deficits, and recurrence rate. RESULTS Forty-six patients (23 men, 23 women) were identified for inclusion in the study with an average age of 47 ± 17 years, BMI of 28 ± 5 kg/m2, and follow-up of 32 ± 45 months. Thirty-nine patients (85%) had schwannomas and 7 (15%) had neurofibromas. Tumors involved the C5 (n = 12), C6 (n = 11), C7 (n = 14), C8 (n = 6), and T1 (n = 3) nerves. Multivariable logistic regression analysis with an area under the curve of 0.85 demonstrated C5 tumor level as an independent predictor of new postoperative weakness (odds ratio 7.4, p = 0.028). Of those patients with new postoperative weakness, 75% improved and 50% experienced complete resolution of their motor deficits. CONCLUSIONS Patients with C5 nerve sheath tumor resections are at higher odds of new postoperative weakness. This may be due to the predominant single innervation of shoulder muscle targets in contrast to other upper extremity muscles that receive input from 2 or more spinal nerves. These findings are important for clinical decision-making and preoperative patient counseling.

Development of the Pectoral Lobed Fin in the Australian Lungfish Neoceratodus forsteri

The evolutionary transition from paired fins to limbs involved the establishment of a set of limb muscles as an evolutionary novelty. In parallel, there was a change in the topography of the spinal nerves innervating appendicular muscles, so that distinct plexuses were formed at the bases of limbs. However, the key developmental changes that brought about this evolutionary novelty have remained elusive due to a lack of data on the development of lobed fins in sarcopterygian fishes. Here, we observed the development of the pectoral fin in the Australian lungfish Neoceratodus forsteri (Sarcopterygii) through synchrotron radiation X-ray microtomography. Neoceratodus forsteri is a key taxon for understanding the fin-to-limb transition due to its close phylogenetic relationships to tetrapods and well-developed lobed fins. At the onset of the fin bud in N. forsteri, there is no mesenchyme at the junction between the axial body wall and the fin bud, which corresponds to the embryonic position of the brachial plexus formed in the mesenchyme in tetrapods. Later, concurrent with the cartilage formation in the fin skeleton, the fin adductor and abductor muscles become differentiated within the surface ectoderm of the fin bud. Subsequently, the girdle muscle, which is homologous to the tetrapod serratus muscle, newly develops at the junction between the axial body wall and the fin. Our study suggests that the acquisition of embryonic mesenchyme at the junction between the axial body wall and the appendicular bud opened the door to the formation of the brachial plexus and the specialization of individual muscles in the lineage that gave rise to tetrapods.