Spectrum of nitrous oxide intoxication related neurological disorders in Korea: a case series and literature review

Background: Nitrous oxide (N2O) is used in surgery and dentistry for its anesthetic and analgesic effects. However, neurological and psychiatric manifestations of N2O abuse have been increasingly reported among Korean adults. The aim of this study was to demonstrate laboratory findings of N2O abuse in Korean patients.Methods: Patients diagnosed with N2O-induced neuropathy or myelopathy from August 2018 to December 2019 were enrolled. Their clinical presentations and laboratory and imaging findings were analyzed.Results: Sensory changes and limb weakness were present in nine of the enrolled patients. The laboratory findings revealed that seven patients had high homocysteine levels and five had high methylmalonic acid levels in their blood. Nerve conductions studies indicated that axonal neuropathy was present in four cases and longer F-wave and Hoffman’s-reflex latencies were present in two cases. Signal changes in cervical spine imaging occurred in five patients, while two had normal results.Conclusions: Chronic N2O abuse can cause neurological damage or psychiatric problems. Because N2O is illegal for recreational use in Korea, patients tend to hide their history of use. Even though the spinal imaging results were normal, clinicians should consider the possibility of N2O use, and further electrophysiological tests should be applied for precise evaluations.

Intracranial Hypotensive Crisis From an Insidious Spinal Cerebrospinal Fluid-Venous Fistula: A Case Report

BACKGROUND AND IMPORTANCE Progressive episodic spells of altered levels of consciousness, often advancing to include paroxysmal autonomic instability, may be indicative of a diencephalic dysfunction underlying spontaneous intracranial hypotension (SIH). A rare, and often indolent, etiology may be spinal cerebrospinal fluid (CSF) leak—an elusive diagnosis, especially in cases of CSF-venous fistula (CVF) that are often missed on routine computed tomography (CT) myelography and magnetic resonance imaging (MRI). CLINICAL PRESENTATION We report an unusual case of a 50-yr-old woman who presented with rapidly progressive cyclical, self-resolving episodes of altered mentation and decreased arousal later in the day. Scrutiny of serial brain MRIs led to a diagnosis of SIH, with severe downward diencephalic and brain stem displacement—resulting in cerebral aqueduct occlusion with obstructive hydrocephalus. Initial clinical improvement occurred with CSF diversion, but the patient quickly deteriorated—developing diencephalic spells, including extensor posturing and severely depressed levels of consciousness. Clinical improvement was seen with stopping CSF diversion and Trendelenburg-positioning. After intensive spinal imaging, dynamic CT myelography identified a left T10 nerve root diverticula and CSF-venous fistula. Surgical obliteration resulted in rapid, profound neurological improvement, and ultimately full neurological recovery by 1 yr. CONCLUSION In our patient, worsening episodes of confusion, postural headaches, and autonomic instability developed due to SIH, which induced profound downward displacement and compression of the diencephalon and brain stem, and accompanied by subsequent obstructive hydrocephalus. Diagnostic persistence identified the CVF, which had caused the complex multifold pathophysiology and clinical presentation. If suspicion remains high for CVF, persistent spinal imaging, particularly with dynamic myelography, may be crucial.

Nutritional neuropathy postoesophagogastrectomy

We report a case of a patient who presented complaining of a 1-week history of progressive lower limb weakness and decreased sensation bilaterally suggestive of a peripheral neuropathy, with vague associated symptoms of fluctuating concentration. Clinically, we suspected a Guillain-Barré variant. However, her functioning continued to decline despite intravenous immunoglobulin therapy, and she had normal spinal imaging studies and CSF analysis. Of note, she had a subtotal oesophagectomy and proximal gastrectomy 20 months previously for oesophageal cancer. We found her to be deficient in vitamin D, vitamin E and copper. She was treated with nutritional supplementation of these vitamins and infusion of trace elements, resulting in a gradual improvement in lower limb power, sensation and coordination, as well as improved cognition and mentation. Monthly outpatient neurology follow-up shows continued improvement in symptoms and return towards baseline functioning with regular infusions of nutritional elements and monitoring of blood levels.

Multiple Spinal CSF Leaks in Spontaneous Intracranial Hypotension. Do They Exist?

Objective:To determine the frequency of multiple spinal CSF leaks in a recent group of patients with spontaneous intracranial hypotension (SIH) who were investigated with digital subtraction myelography (DSM).Methods:This observational study was conducted using data from a prospectively maintained data base of patients who meet the International Classification of Headache Disorders (ICHD)-III criteria for SIH. The patient population consisted of a consecutive group of 745 patients with SIH who underwent DSM between March 2009 and February 2020. Based on the results of DSM, participants were classified according to type and number of spinal CSF leaks.Results:Among 398 patients with SIH and extradural CSF on spinal imaging, multiplicity of CSF leaks was observed in none of 291 patients with type 1a ventral leaks and in four (6.2%) of 65 patients with type 1b (postero-) lateral leaks. Among 97 patients with SIH from spinal CSF-venous fistulas (type 3 leaks) who did not have extradural CSF on spinal imaging, nine patients (9.3%) had multiple fistulas (p<0.0001 for comparison between groups). Type 3 and type 1a or 1b CSF leaks coexisted in an additional five patients.Conclusions:Among patients with SIH, multiplicity of CSF leaks was observed radiographically in none of the patients with ventral leaks, in 6% of patients with lateral leaks, and in 9% of patients with CSF-venous fistulas. These results suggest that patients with SIH can be reassured that the occurrence of multiple CSF leaks is negligible to uncommon at most, depending on type of CSF leak.

Watchful waiting as a strategy to reduce low-value spinal imaging: study protocol for a randomized trial

Background Patients with acute low back pain frequently request diagnostic imaging, and clinicians feel pressure to acquiesce to such requests to sustain patient trust and satisfaction. Spinal imaging in patients with acute low back pain poses risks from diagnostic evaluation of false-positive findings, patient labeling and anxiety, and unnecessary treatment (including spinal surgery). Watchful waiting advice has been an effective strategy to reduce some low-value treatments, and some evidence suggests a watchful waiting approach would be acceptable to many patients requesting diagnostic tests. Methods We will use key informant interviews of clinicians and focus groups with primary care patients to refine a theory-informed standardized patient-based intervention designed to teach clinicians how to advise watchful waiting when patients request low-value spinal imaging for low back pain. We will test the effectiveness of the intervention in a randomized clinical trial. We will recruit 8–10 primary care and urgent care clinics (~ 55 clinicians) in Sacramento, CA; clinicians will be randomized 1:1 to intervention and control groups. Over a 3- to 6-month period, clinicians in the intervention group will receive 3 visits with standardized patient instructors (SPIs) portraying patients with acute back pain; SPIs will instruct clinicians in a three-step model emphasizing establishing trust, empathic communication, and negotiation of a watchful waiting approach. Control physicians will receive no intervention. The primary outcome is the post-intervention rate of spinal imaging among actual patients with acute back pain seen by the clinicians adjusted for rate of imaging during a baseline period. Secondary outcomes are use of targeted communication techniques during a follow-up visit with an SP, clinician self-reported use of watchful waiting with actual low back pain patients, post-intervention rates of diagnostic imaging for other musculoskeletal pain syndromes (to test for generalization of intervention effects beyond back pain), and patient trust and satisfaction with physicians. Discussion This trial will determine whether standardized patient instructors can help clinicians develop skill in negotiating a watchful waiting approach with patients with acute low back pain, thereby reducing rates of low-value spinal imaging. The trial will also examine the possibility that intervention effects generalize to other diagnostic tests. Trial registration ClinicalTrials.govNCT 04255199. Registered on January 20, 2020

How to interpret spinal imaging in paediatric trauma

Spinal injuries in children are fortunately rare; however, it is important that they are assessed and managed in a timely manner. A systematic approach to traumatic spinal injuries should be used, by following recent evidence and national protocols, in order to avoid misinterpretation and potentially, inappropriate discharge. The aim of this article is to highlight the concepts of spinal imaging in paediatric trauma with regards to indications, interpretation and limitations.