Anterior cysts of the spine: A difficult differential diagnosis to amyotrophic lateral sclerosis

Bibrachial amyotrophy as a rare manifestation of intraspinal fluid collection: a case report and systematic review

INTRODUCTION

Intraspinal cerebrospinal fluid (CSF) collection has been reported as a rare cause of lower motor neuron (LMN) disorder. We report a case of bibrachial diplegia associated with intraspinal CSF collection and perform a systematic literature review.

PATIENT AND METHODS

A 52-year-old man developed a bibrachial amyotrophy over 6 years, confirmed by the presence of cervical subacute neurogenic changes at electromyography (EMG). Brain magnetic resonance imaging (MRI) revealed cerebral siderosis, while spine MRI showed a ventral longitudinal intraspinal fluid collection (VLISFC) from C2 to L2. No CSF leakage was localized at myelography; a conservative treatment was chosen. We searched for all published cases until 30th April 2023 and extrapolated data of 44 patients reported in 27 publications.

RESULTS

We observed a male predominance, a younger disease onset compared to amyotrophic lateral sclerosis, and a quite long disease duration, highlighting a slow disease progression. LMN signs were more frequently bilateral, mostly involving C5-C6 myotomes. Around 61% of patients presented additional symptoms, but only three referred to a history of headache. Accordingly, CSF opening pressure was mostly normal. Spinal MRI revealed the presence of VLISFC and in some cases myelomalacia. EMG patterns displayed both chronic and subacute neurogenic change in the cervical region. The disease course mainly depended on the treatment choice, which was mostly represented by a surgical approach when a specific dural defect was detected by imaging.

CONCLUSION

Bibrachial diplegia due to VLISFC can be a treatable cause of focal amyotrophy and presents some clinical and radiological "red flags" which cannot be missed by a clinical neurologist.

Pearls & Oy-sters: Bibrachial Amyotrophy From a Dural Tear

Bibrachial amyotrophy signifies a clinical phenotype characterized by weakness in both upper extremities with preserved strength in the face, neck, and lower extremities. The underlying causes of bibrachial amyotrophy are broad. We report a patient exhibiting bibrachial amyotrophy who initially received a diagnosis of amyotrophic lateral sclerosis (ALS); however, his clinical course and NCS/EMG were atypical for ALS. Further evaluation demonstrated dural tears with CSF leak, resulting in a compressive extradural fluid collection, ventral myelopathy, and intracranial hypotension. Dural tear and ALS have overlapping features, including the manifestation of the bibrachial amyotrophy phenotype and the presence of T2 hyperintensities in the anterior horn cells, recognized by an "owl's eye" appearance on spine MRI. Clinical and radiologic vigilance is required to identify rare cases of dural tear causing ventral myelopathy that manifest as bibrachial amyotrophy.

Spinal Anterior Dural Dissection: Moving From Differential to Unifying Diagnosis

BACKGROUND AND OBJECTIVES

Cerebrospinal fluid (CSF) collections extending longitudinally at the anterior aspect of the spinal dura have been reported in association with various conditions and under multiple names. The aim of this study was to report cases associated with brachial amyotrophy (BA) and examine its relationship with other clinical variants.

METHODS

We conducted a retrospective cohort study including patients who presented with a motor deficit of the upper limbs and an anterior interdural CSF collection on spinal MRI. We performed a systematic review of the literature to include cases revealed by BA.

RESULTS

Seven patients presenting with BA and a confirmed dural dissection on spinal MRI were included. All patients were male with a slowly progressing history of asymmetrical and proximal motor deficit of the upper limbs. Chronic denervation affecting mostly C5 and C6 roots was found on electroneuromyography. Spinal MRI demonstrated an anterior CSF collection dissecting the interdural space and exerting a traction on cervical motor roots. Dynamic computed tomography myelogram localized the dural defect every time it was performed (4/7 cases), and surgical closure was possible for 3 patients, leading to resolution of the collection. Literature review yielded 18 other published cases of spinal dural dissections revealed by BA, including 4 in association with spontaneous intracranial hypotension and 4 others in association with superficial siderosis.

CONCLUSION

We propose a unifying diagnosis termed "spinal anterior dural dissection" (SADD) to encompass spinal dural CSF collections revealed by BA (SADD-BA), spontaneous intracranial hypotension (SADD-SIH), or superficial siderosis (SADD-SS).

Amyotrophic lateral sclerosis mimics

Amyotrophic lateral sclerosis (ALS) is the most common adult-onset motor neuron disorder characterized by progressive degeneration of cortical, bulbar, and spinal motor neurons. When a patient presents with a progressive upper and/or lower motor syndrome, clinicians must pay particular attention to any atypical features in the history and/or clinical examination suggesting an alternate diagnosis, as up to 10% percent of patients initially diagnosed with ALS have a mimic of ALS. ALS is a clinical diagnosis and requires the exclusion of other disorders that may have similar presentations but a more favorable prognosis or an effective therapy. Because there is currently no specific diagnostic biomarker that is sensitive or specific for ALS, understanding the spectrum of clinical presentations of ALS and its mimics is paramount. While true mimics of ALS are rare, the clinician must correctly identify these disorders to avoid the misdiagnosis of ALS and to initiate effective treatment where available.

Ventral longitudinal intraspinal fluid collection: Rare presentation as brachial amyotrophy and intracranial hypotension

CONTEXT

Ventral longitudinal intraspinal fluid collection (VLISFC) presenting as hand amyotrophy has been described only in a few cases and there are no reports on associated intracranial CSF hypovolemia (ICH). We describe the clinical and imaging findings of a case with combined brachial amyotrophy and ICH secondary to VLISFC.

FINDINGS

A 31 year old man presented with severe positional neck discomfort, radiating pain, progressive asymmetrical wasting and weakness of distal upper limbs. Contrast Magnetic Resonance Imaging (MRI) of the spine demonstrated a ventral extradural intraspinal fluid collection extending from upper border of C6 to lower border of T3 vertebra with pockets of dorsal collection. Three-dimensional constructive interference in steady state (CISS 3D) used in spinal imaging for identification of CSF leak corroborated with the extent seen on T2 sagittal sections; however, the site of the leak was not identified. After a year he developed disturbing postural headache which was relieved in recumbent position. Follow up MRI of brain was normal while spine demonstrated significant cervical cord atrophy and bilateral cord white matter hyperintensities. Conclusion / Clinical Relevance: We report this unusual case where local compression by VLISFC located at the cervical and upper thoracic level not only caused distal bi-brachial amyotrophy mimicking Hirayama disease but also led to secondary intracranial hypotension. An early identification and intervention could possibly have prevented the onset of ICH.

A rare anterior spinal epidural cyst mimicking Hirayama disease

INTRODUCTION

Hirayama disease is a rare focal motor neuron disorder that manifests as slowly progressive unilateral or bilateral hand weakness and atrophy.

METHODS

The case report of a young man who presented with the phenotype of Hirayama disease indicated an extensive anterior cervical epidural arachnoid cyst.

RESULTS

A 34-year-old man presented with a 5-year history of slowly progressive hand and forearm weakness and atrophy. Nerve conduction studies demonstrated low median and ulnar motor amplitudes, and EMG demonstrated fibrillation potentials and long-duration, high-amplitude motor unit potentials in C6-T4-innervated muscles. MRI demonstrated a longitudinally extensive anterior spinal epidural cyst extending from C2 to L1. The patient had improved hand strength after surgery.

CONCLUSIONS

Anterior cervical epidural spinal cysts should be considered in the differential diagnosis in patients who present with slowly progressive hand weakness.

Spinal cord markers in ALS: diagnostic and biomarker considerations

Despite considerable involvement of the spinal cord in amyotrophic lateral sclerosis (ALS), current biomarker research is primarily centred on brain imaging and CSF proteomics. In clinical practice, spinal cord imaging in ALS is performed primarily to rule out alternative conditions in the diagnostic phase of the disease. Quantitative spinal cord imaging has traditionally been regarded as challenging, as it requires high spatial resolution while minimizing partial volume effects, physiological motion and susceptibility distortions. In recent years however, as acquisition and post-processing methods have been perfected, a number of exciting and promising quantitative spinal imaging and electrophysiology techniques have been developed. We performed a systematic review of the trends, methodologies, limitations and conclusions of recent spinal cord studies in ALS to explore the diagnostic and prognostic potential of spinal markers. Novel corrective techniques for quantitative spinal cord imaging are systematically reviewed. Recent findings demonstrate that imaging techniques previously used in brain imaging, such as diffusion tensor, functional and metabolic imaging can now be successfully applied to the human spinal cord. Optimized electrophysiological approaches make the non-invasive assessment of corticospinal pathways possible, and multimodal spinal techniques are likely to increase the specificity and sensitivity of proposed spinal markers. In conclusion, spinal cord imaging is an emerging area of ALS biomarker research. Novel quantitative spinal modalities have already been successfully used in ALS animal models and have the potential for development into sensitive ALS biomarkers in humans.