Axonal projection of the medullary expiratory neurons in the feline thoracic spinal cord

Expiratory neurons in the caudal ventral respiratory group extend descending axons to the lumbar and sacral spinal cord, and they possess axon collaterals, the distribution of which has been well-documented. Likewise, these expiratory neurons extend axons to the thoracic spinal cord and innervate thoracic expiratory motoneurons. These axons also give rise to collaterals, and their distribution may influence the strength of synaptic connectivity between the axons and the thoracic expiratory motoneurons. We investigated the distribution of axon collaterals in the thoracic spinal cord using a microstimulation technique. This study was performed on cats; one cat was used to make an anatomical atlas and six were used in the experiment. Extracellular spikes of expiratory neurons were recorded in artificially ventilated cats. The thoracic spinal gray matter was microstimulated from dorsal to ventral sites at 100-μm intervals using a glass-insulated tungsten microelectrode with a current of 150-250 μA. The stimulation tracks were made at 1 mm intervals along the spinal cord in segments Th9 to Th13, and the effective stimulating sites of antidromic activation in axon collaterals were systematically mapped. The effective stimulating sites in the contralateral thoracic spinal cord with expiratory neurons in the caudal ventral respiratory group (cVRG) occupied 14.4% of the total length of the thoracic spinal cord examined. The mean percentage of effective stimulating tracks per unit was 18.6 ± 4.4%. The distribution of axon collaterals of expiratory neurons in the feline thoracic spinal cord indeed resembled that reported in the upper lumbar spinal cord. We propose that a single medullary expiratory neuron exerts excitatory effects across multiple segments of the thoracic spinal cord via its collaterals.

Thoracic Anterior Spinal Cord Herniation: Treatment and Prognosis Outcome of Seven Patients

BACKGROUND

This study aimed to investigate the diagnosis and treatment of thoracic anterior spinal cord herniation, a rare condition.

METHODS

Clinical data of 7 patients diagnosed with thoracic anterior spinal cord herniation were analyzed. All patients were diagnosed with a complete preoperative examination and scheduled for surgical treatment. In addition, regular follow-up was performed after the surgery, and the operation's efficacy was evaluated according to clinical symptoms, imaging findings, and improvement in neurologic function.

RESULTS

All patients underwent spinal cord release with an anterior dural patch. Notably, no severe postoperative surgical complications were observed. All patients were followed up for 12-75 months, with an average duration of approximately 46.5 months. Post-operative pain symptoms were controlled, neurological dysfunction and related symptoms improved to varying degrees, and anterior spinal cord herniation did not recur. The modified Japanese Orthopedic Association score at the last follow-up was significantly higher than the preoperative score.

CONCLUSIONS

Clinicians should avoid misdiagnosing patients with thoracic anterior spinal cord herniation with intervertebral disc herniation, arachnoid cysts, and other related diseases, and patients should undergo surgical treatment as early as possible. In addition, surgical treatment can protect the neurologic function of patients and effectively prevent the aggravation of clinical symptoms.

Illustrative resection of mixed intra- and extramedullary thoracic spinal cord capillary hemangioma

Background

Capillary hemangiomas are typically superficial benign tumors of the cutaneous and mucosal tissues of the face and neck in pediatric patients. In adults, they typically occur in middle-aged males who present with pain, myelopathy, radiculopathy, paresthesias, and bowel/bladder dysfunction. The optimal treatment for intramedullary spinal cord capillary hemangiomas is gross total/en bloc resection.

Methods

Here, we present a 63-year-old male with increasing right greater than left lower extremity numbness/ weakness, attributed to a T8-9 mixed intra- and extramedullary capillary hemangioma.

Results

One year following complete lesion resection, the patient used an assistive device to ambulate and continued to improve neurologically.

Conclusion

We presented a 63-year-old male whose paraparesis was attributed to a T8-9 mixed intra- and extramedullary capillary hemangioma who did well following total en bloc lesion resection. In addition to this case study/technical note, we provide a 2-D intraoperative video detailing the resection technique.

White Cord Syndrome after Thoracic Cord Decompression in a Pediatric Patient

INTRODUCTION

White cord syndrome (WCS) is a rare phenomenon which causes acute neurologic deterioration after a chronically compressed spinal cord is surgically decompressed, resulting in a T2-hyperintense signal to appear in the cord. We present the first case of pediatric WCS in the thoracic spine and the first to show complete resolution of symptoms.

CASE PRESENTATION

A 3-year-old girl presented with difficulty ambulating due to pain caused by T4-8 spinal cord compression from a mass of ganglioneuromatous tissue, consistent with her previously treated mediastinal neuroblastoma. She underwent laminoplasty and microsurgical debulking of the mass. She developed severe bilateral leg weakness on postoperative day 1. Magnetic resonance imaging (MRI) showed T2 hyperintensity in the spinal cord from T1 to T10 without enhancement, concerning for WCS. She was started on high-dose steroids and monitored. Her strength improved to 3/5 in both legs prior to discharge to inpatient rehabilitation. On the latest follow-up, 4 months after surgery, she did not demonstrate any neurologic deficits and was ambulating well. Follow-up MRIs have showed continued improvement in the T2 hyperintensity.

DISCUSSION/CONCLUSION

Most cases in the literature occur in older adults with chronic cervical compression. Only 1 pediatric case, caused by a cervical arachnoid cyst, has been reported and only resulted in partial improvement. Our case is the first pediatric case of WCS to occur in the thoracic spine, the first pediatric case to demonstrate complete resolution, and the first case of any age to start to establish a length of time the compression is needed to be at risk for WCS.

Imaging of the thoracic spinal cord using radially sampled averaged magnetization inversion recovery acquisitions

BACKGROUND

Spinal cord (SC) gray and white matter atrophy quantification by advanced morphometric MRI can help to better characterize the course of neurodegenerative diseases in vivo, such as e.g. lower motor neuron disorders. Imaging the lower thoracic cord - containing those motor neurons that control leg function - could be particularly informative, however, is challenging due to tissue composition, physiological motion and large field of views.

NEW METHOD

An "averaged magnetization inversion recovery acquisitions" (AMIRA) approach with a radial k-space acquisition scheme was developed. The method is designed for morphometric SC imaging with a focus on the thoracic SC.

RESULTS

In a typical setting, radial AMIRA acquires transverse slices with a high 0.50 × 0.50mm² in-plane resolution and a pronounced positive contrast between thoracic gray and white matter, within typically 2:39 min. Additional proof-of-concept measurements in patients demonstrate that such contrast and resolving capability is indeed necessary to assess potential atrophy of the anterior horns.

COMPARISON WITH EXISTING METHOD(S)

Radial AMIRA utilizes two benefits of radial MRI techniques: being generally less prone to motion effects and that fold over artifacts can manifest less intrusively. These benefits are united with the original AMIRA approach which allows the contrast to be 'tuned' and improved based on the combination of five simultaneously acquired images of different tissue contrast.

CONCLUSIONS

Radial AMIRA is a promising approach for in vivo SC gray and white matter atrophy visualization and quantification in lower motor neuron diseases and other autoimmune or genetic diseases involving the entire (not only cervical) spinal cord.

Further observations on cardiac modulation of thoracic motoneuron discharges

Previous analyses of recordings of alpha motoneuron discharges from branches of the intercostal and abdominal nerves in anesthetized cats under neuromuscular blockade demonstrated modulation with the cardiac cycle. This modulation was interpreted as evidence that thoracic somatosensory afferents, most likely muscle spindles, provide a signal to the CNS that could contribute to cardiac interoception. Here, two aspects of these observations have been extended. First, new measurements of thoracic and abdominal EMG activity in spontaneously breathing dogs show that a very similar modulation exists in these rather different circumstances. Second, further analysis of the cat recordings shows that cardiac modulation of the discharges of bulbospinal neurons that transmit the expiratory drive to thoracic motoneurons is weak and of an inappropriate time-course to be a contributor to the effect seen in the motoneurons.