A recent surge of nitrous oxide misuse around London which merits a public health warning.

BACKGROUND: Use of nitrous oxide (N2O) gas for recreational purposes by young people is increasingly recognized as a public health hazard in the UK. METHODS: We looked at the hospital records of patients admitted over the last 4 years to a single neurological centre in Essex to determine the demographics, presentation, and management of patients presenting with symptoms of N2O toxicity from its recreational use. RESULTS: Of the 17 patients (mean age = 22.9 ± 3 years) admitted between September 2018 and October 2022, 70% were admitted between January and October 2022. All patients reported limb paraesthesiae and 16/17 reported (95%) imbalance; 11/17 (65%) showed objective limb weakness. Serum B12 concentration was low in 9/17 (53%). Plasma methylmalonic acid (n = 7) and homocysteine (n = 8) levels were elevated in all patients tested. Spinal cord Magnetic Resonance Imaging (MRI) imaging was abnormal in 10/17 (59%) patients. Nerve conduction studies were abnormal in 10/13 (77%) patients, with evidence of a symmetric, length-dependent, large fibre neuropathy. CONCLUSIONS: There has been a recent surge of cases with neurological complications of recreational N2O abuse in the UK, with a relatively greater rate in 2022. Greater awareness of this condition amongst clinicians and health regulators is urgently required to prevent harm from N2O misuse in young people.

Potential Surgical Implications of Internal Jugular Stenosis in a Craniocervical Junction Meningioma.

We report a case of a 61-year-old lady presenting with several weeks of progressive left-sided weakness, and found to have a foramen magnum meningioma. She was counselled on surgical resection of the tumour, and a preoperative computed tomography angiogram (CTA) was obtained for operative planning purposes. CTA demonstrated incidental bilateral internal jugular vein (IJV) stenosis, with enlarged extracranial collateral vessels and elongated styloid processes. The main surgical concern was potential injury of the extracranial collateral vessels during operative exposure, which may compromise her intracranial venous outflow in light of the IJV stenosis. A doppler ultrasound scan of the IJVs was performed, which demonstrated that blood flow was still present through both vessels. Through careful soft tissue dissection during surgery, potential complications and injury to the extracranial collaterals were avoided. We performed a literature review of the incidence of IJV stenosis, its associated conditions, and potential surgical implications. Complications from injury to vital collateral extracranial vessels should be considered during preoperative planning in patients with anatomical variants or risk factors for IJV stenosis, as seen in this case.

Validation of an artificial intelligence solution for acute triage and rule-out normal of non-contrast CT head scans.

PURPOSE: Non-contrast CT head scans provide rapid and accurate diagnosis of acute head injury; however, increased utilisation of CT head scans makes it difficult to prioritise acutely unwell patients and places pressure on busy emergency departments (EDs). This study validates an AI algorithm to triage patients presenting with Intracranial Haemorrhage (ICH) or Acute Infarct whilst also identifying a subset of patients as Normal, with the potential to function as a rule-out test. METHODS: In total, 390 CT head scans were collected from 3 institutions in the UK, US and India. Ground-truth labels were assigned by 3 FRCR consultant radiologists. AI performance, as well as the performance of 3 independent radiologists, was measured against ground-truth labels. RESULTS: The algorithm showed AUC values of 0.988 (0.978-0.994), 0.933 (0.901-0.961) and 0.939 (0.919-0.958) for ICH, Acute Infarct and Normal, respectively. Sensitivity/specificity for ICH and Acute Infarct were 0.988/0.925 and 0.833/0.927, respectively, compared to 0.907/0.991 and 0.618/0.977 for radiologists. AI rule-out of Normal scans achieved 0.93% negative predictive value (NPV) for the removal of 54.3% of Normal cases, compared to 86.8% NPV for radiologists. CONCLUSION: We show our algorithm can provide effective triage of ICH and Acute Infarct to prioritise acutely unwell patients. AI can also benefit clinical accuracy, with the algorithm identifying 91.3% of radiologist false negatives for ICH and 69.1% for Acute Infarct. Rule-out of Normal scans has huge potential for workload management in busy EDs, in this case removing 27.4% of all scans with no acute findings missed.

Respiratory difficulty with palatal, laryngeal and respiratory muscle tremor in adult-onset Alexander's disease.

Sleep apnoea and respiratory difficulties are reported in adult-onset Alexander's disease (AOAD), an autosomal-dominant leukodystrophy that presents mainly with progressive ataxia. We demonstrate for the first time that the respiratory symptoms can result from association of palatal tremor with a similar tremor of laryngeal and respiratory muscles that interrupts normal inspiration and expiration.A 60-year-old woman presented with progressive ataxia, palatal tremor and breathlessness. MRI revealed medullary atrophy, bilateral T2 hyperintensities in the dentate nuclei and hypertrophic olivary degeneration (HOD). AOAD was confirmed genetically with a positive glial fibrillary acidic protein (GFAP) mutation. Electrophysiological study revealed 1.5 Hz rhythmic laryngeal and respiratory muscle activity. Her respiratory symptoms were significantly improved at night with variable positive pressure ventilation.This case illustrates that palatal tremor in AOAD, and potentially in other conditions, may be associated with treatable breathlessness due to a similar tremor of respiratory muscles.

Anti-collapsin response mediator protein 5 encephalitis masquerading as a low-grade brain tumour.

A 71-year-old woman presented acutely with seizures; her MRI suggested a low-grade glioma of the right temporal lobe. Over the preceding 18 months, she had developed progressive limb chorea and orofacial dyskinesia. Examination showed a predominantly amnestic cognitive profile. Initial investigations were normal, but later she was found to have antibodies to collapsin response mediator protein 5 (also called CV2). Her symptoms and neuroimaging abnormalities gradually improved without treatment. Four months later, surveillance imaging with (18)F-fluorodeoxyglucose-positron-emission tomography revealed a lesion confirmed by biopsy as a TX, N2, M0 small-cell lung cancer. This case is unusual for the strikingly unilateral neuroimaging abnormalities, which led to an initial misdiagnosis, and the spontaneous symptomatic improvement without treatment. In retrospect, the co-occurrence of paraneoplastic chorea, limbic encephalitis and neuropathy in the presence of an occult lung tumour make this almost a 'full house' of symptoms associated with antibodies to collapsin response mediator protein 5. It underlines the importance in clinical reasoning of avoiding the cognitive errors of premature closure and anchoring.

A rare stapes abnormality.

The aim of this study is to increase awareness of rare presentations, diagnostic difficulties alongside management of conductive hearing loss and ossicular abnormalities. We report the case of a 13-year-old female reporting progressive left-sided hearing loss and high resolution computed tomography was initially reported as normal. Exploratory tympanotomy revealed an absent stapedius tendon and lack of connection between the stapes superstructure and footplate. The footplate was fixed. Stapedotomy and stapes prosthesis insertion resulted in closure of the air-bone gap by 50 dB. A review of world literature was performed using MedLine. Middle ear ossicular discontinuity can result in significant conductive hearing loss. This can be managed effectively with surgery to help restore hearing. However, some patients may not be suitable or decline surgical intervention and can be managed safely conservatively.

Reversible cerebral vasoconstriction syndrome as a cause of thunderclap headache: a retrospective case series study.

Thunderclap headache is a common emergency department presentation. Although subarachnoid hemorrhage (SAH) should be the first diagnosis to exclude, reversible cerebral vasoconstriction syndrome (RCVS) is an important alternative cause, which may be commoner than appreciated. Reversible cerebral vasoconstriction syndrome is characterized by multifocal narrowing of cerebral arteries, typically manifested by acute, severe headache with or without neurologic deficits. To compare and discuss the clinical and radiologic characteristics of patients with RCVS. We report 4 cases of RCVS, presenting at a single unit in 1 year. All presented with thunderclap headache, whereas half of them had additional neurologic symptoms such as right homonymous hemianopia, right-sided weakness, and slurred speech. Brain computed tomography was normal in 2 of our patients, but subsequent cerebrospinal fluid analysis revealed xanthochromia consistent with SAH. The remaining 2 patients demonstrated intracerebral hemorrhage on computed tomography. All of our patients underwent digital subtraction angiography that showed segmental narrowing and dilatation of one or more cerebral arteries without any signs of aneurysm. Repeat digital subtraction angiography after 3 months was entirely normal prompting the diagnosis of RCVS. Thunderclap headache requires urgent workup to identify the underlying cause. Although SAH is the most important diagnosis to exclude in the first instance, emergency physicians should be aware of other causes and how they present, such as RCVS. Early recognition of this condition is important in order to remove precipitants, avoid unnecessary investigations, and inform patients about their prognosis.

Do immediate cytology and specialist radiologists improve the adequacy of ultrasound-guided fine-needle aspiration cytology?

OBJECTIVE: To assess whether a dedicated "1-stop" neck lump clinic has improved the percentage of adequate fine-needle aspiration cytology (FNAC) samples and reduced the need for repeat FNAC. STUDY DESIGN: Retrospective review. SETTING: District General Hospital in the United Kingdom. SUBJECTS AND METHODS: Patients attending for ultrasound-guided FNAC over a 6-month period from August 2012 to February 2013. Patients were placed in 4 groups: group 1, FNAC performed by any of the subspecialist radiologists with cytology support (n = 100); group 2, FNAC performed by general radiologists without cytology support (n = 112); group 3, FNAC performed by a particular subspecialist radiologist with cytology support (n = 61); and group 4, FNAC performed by the same subspecialist radiologist without cytology support (n = 125). RESULTS: There was a significantly higher rate of adequacy of FNAC in the presence of a subspecialist radiologist with immediate cytology (group 1) versus a general radiologist without cytology support (group 2; 87/100 vs 63/112, P = .0001), a significantly higher rate of adequacy of FNAC in the presence of cytology support with the same radiologist (group 3 vs group 4, 55/61 vs 97/125, P = .04), and a significantly higher rate of adequacy of FNAC in the presence of a subspecialist radiologist versus a general radiologist without cytology support (group 4 vs group 2, 97/125 vs 63/112, P = .0005). CONCLUSION: Immediate cytology and the presence of a subspecialist radiologist increase the adequacy of FNAC. The adequacy rate of non-cytology-supported FNAC or nonsubspecialist FNAC is below the adequate rate expected from the literature or as recommended in national guidelines.

Wholly endoscopic permeatal removal of a petrous apex cholesteatoma.

We report a case of a petrous apex cholesteatoma which was managed with a wholly endoscopic permeatal approach. A 63-year-old Caucasian male presented with a 10-year history of right-sided facial palsy and profound deafness. On examination in our clinic, the patient had a grade VI House-Brackmann paresis, otoscopic evidence of attic cholesteatoma behind an intact drum, and extensive scarring of the face from previous facial reanimation surgery. Imaging review was suggestive of petrous apex cholesteatoma. An initial decision to manage the patient conservatively was later reviewed on account of the patient suffering recurrent epileptic seizures. A wholly endoscopic permeatal approach was used with successful outcomes. In addition to the case report we also provide a brief description of the technique and a review of the relevant literature.

Peripartum isolated cortical vein thrombosis in a mother with postdural puncture headache treated with an epidural blood patch.

A 32-year-old woman presented with low pressure headache 3 days after delivery of her baby. An assessment of postdural puncture headache was made. This was initially treated with analgesia, caffeine, and fluids for the presumed cerebrospinal fluid (CSF) leak. The woman was readmitted two days after her hospital discharge with generalised seizures. A brain scan showed features of intracranial hypotension, and she was treated for CSF leak using an epidural blood patch. Her symptoms worsened and three days later, she developed a left homonymous quadrantanopia. An MRI scan confirmed a right parietal haematoma with evidence of isolated cortical vein thrombosis (ICVT).

Delayed caroticocavernous fistula after stent-assisted coil embolization of intracavernous carotid aneurysm: should we manage conservatively?

Constructive endovascular techniques remain the mainstay for the treatment of cavernous carotid aneurysms due to their efficacy. However, they do harbor risks of complications, such as thromboembolic events, arterial injuries, and vessel occlusions. A 58-year-old lady presented with delayed caroticocavernous fistula (CCF) 1 month after stent-assisted coil embolization of a cavernous carotid aneurysm (CCA). Following this, her caroticocavernous fistula resolved spontaneously with no further intervention. Our case demonstrates a unique presentation of a CCF as a delayed complication of stent-assisted coil embolization of CCA and the spontaneous resolution of the CCF. Symptomatic CCFs are commonly treated as an emergency in many institutions and the question arises as to whether we should adopt a conservative policy in the light of this case report.

Paravertebral cervical chordoma--a case report.

Chordomas constitute <5% of vertebral column tumours and a third of these arise in the upper cervical spine and tend to be clival - usually midline, with occasional eccentric extension. We report a case of cervical chordoma presenting as a lateral neck mass and discuss its origin, diagnosis and management.

Delayed fibrotic obliteration of the spinal subarachnoid space after cerebral aneurysmal subarachnoid hemorrhage: case report.

OBJECTIVE: Widespread fibrotic obliteration of the spinal subarachnoid space after cerebral aneurysmal subarachnoid hemorrhage (SAH) is rare. CLINICAL PRESENTATION: A 57-year-old woman presented with the gradual development of a spastic paraparesis. Two years earlier, she experienced a cerebral aneurysmal SAH that was successfully managed with endovascular coiling. However, the SAH was complicated by transient aseptic meningitis and hydrocephalus. Magnetic resonance imaging and computed tomographic myelography at the time of admission 2 years after SAH revealed widespread cystic obliteration of the thoracic subarachnoid space. INTERVENTION: Through an extensive laminoplasty, multiple non-communicating fibrotic cysts, intimately adherent to the pia, were found to have obliterated the spinal subarachnoid space. A full communication between all cysts and the subarachnoid space was ultimately established using a Fogarty catheter. The cerebrospinal fluid was clear and colorless, with normal microscopy. Histopathological examination revealed non-specific fibrosis with scattered lymphocytes and uniform hemosiderosis. CONCLUSION: In addition to precipitating leptomeningeal fibrosis within the convexity subarachnoid space and/or arachnoid granulations (causing delayed hydrocephalus), cerebral aneurysmal SAH may also rarely elicit widespread symptomatic fibrotic obliteration of the spinal subarachnoid space. Such cases seem to be characterized by a posterior circulation, Fisher Grade 3 to 4, aneurysmal SAH, and, when circumscribed and cystic, seem amenable to surgical decompression.

The implications of ISAT and ISUIA for the management of cerebral aneurysms during pregnancy.

Both the International Subarachnoid Aneurysm Trial (ISAT) and the International Study on Unruptured Intracranial Aneurysms (ISUIA) have been widely extrapolated to influence the management of actual or anticipated aneurysmal subarachnoid hemorrhage (SAH). However, it remains possible that sub-groups exist for which such extrapolation might subsequently prove premature. In this review, we discuss the implications that such extrapolation may potentially have for one such SAH sub-group: the clinically rare scenario of SAH in pregnancy.

Lumbar extradural arteriovenous malformation: case report and literature review.

BACKGROUND CONTEXT: Most spinal arteriovenous malformations (AVMs) are dural arteriovenous fistulas in which a singularly intradural venous drainage emanates from an extradural nidus. A pure extradural spinal arteriovenous malformation (E-AVM), in the absence of a vertebral body (cavernous) hemangioma, is extremely rare, and full clinical, radiological, and operative descriptions are scant. PURPOSE: To fully document the rare occurrence of a symptomatic E-AVM producing spinal claudication. STUDY DESIGN: Case report. PATIENT SAMPLE: One patient. OUTCOME MEASURES: Radiological and functional. METHODS: This 62-year-old man presented with 6-month progressive spinal claudication, leg weakness, and diminished sensation. Electromyography revealed bilateral acute and chronic partial degeneration of L3-S1 nerve roots. Magnetic resonance imaging revealed moderate canal stenosis between L2-L4, with prominent epidural veins on the left at L3-L4. Spinal angiography was unsuccessful, and computed tomographic myelography merely confirmed minimal lumbosacral root filling. At decompressive L2-L4 laminectomy, inadvertent hemorrhage from varicose epidural veins released arterialized blood under considerable pressure. Only minor clinical improvement was noted after this procedure. Spinal angiography 6 weeks later subsequently confirmed an E-AVM on the left at L3-L4 which was successfully embolized. RESULTS: Follow-up at 8 weeks after this procedure confirmed significantly increased walking distance, improved distal sensation, and normal power in both legs, with insignificant claudication. CONCLUSIONS: When associated with canal stenosis, E-AVMs may exacerbate claudication by both compressive and venous-hypertensive mechanisms. Treatment should be by embolization, with laminectomy deferred.

Acute obstructive hydrocephalus associated with infratentorial subdural hygromas complicating Chiari malformation Type I decompression. Report of two cases and literature review.

Obstructive hydrocephalus complicating foramen magnum decompression (FMD) for a Chiari malformation (CM) Type I is rare. Two female patients (17 and 55 years old) presented with strain-related headaches. In both cases magnetic resonance (MR) imaging studies confirmed a CM Type I, which was accompanied by syringomyelia in one case. Both patients underwent uncomplicated FMD with good initial recovery. Unfortunately, conditions in both patients deteriorated, with severe headaches occurring between Days 5 and 6 post-FMD. Decreased consciousness occurred in one case. In both patients, computerized tomography scanning demonstrated an acute obstructive hydrocephalus associated with bilateral infratentorial extraaxial fluid collections (EAFCs). In addition, left parafalcine and convexity EAFCs were present in one case. An emergency external ventricular drain was required in one patient, with delayed conversion to a ventriculo-peritoneal shunt. Spontaneous resolution occurred in the other patient without neurosurgical intervention. In both cases, MR imaging confirmed that each EAFC was subdural, resembled cerebrospinal fluid (CSF), and had distorted the superior cerebellum anteroinferiorly. Despite upper fourth ventricle/aqueduct compromise in one case, normal aqueduct flow artifacts were apparent on examination. All EAFCs resolved spontaneously. Obstructive hydrocephalus complicating FMD is rare but invariably associated with infratentorial EAFCs, which were confirmed to be subdural hygromas in this report. The authors assert that hydrocephalus results from upper fourth ventricle/aqueduct compromise as a result of CSF subdural dissection following a pinhole arachnoid tear on durotomy. Because such hygromas spontaneously resolve, permanent shunt insertion should be avoided.

Intracranial aneurysms treated with endovascular coils: detection of recurrences using unenhanced and contrast-enhanced transcranial color-coded duplex sonography.

BACKGROUND AND PURPOSE: Because neck recurrence after endovascular treatment of intracranial aneurysms (IAs) is not uncommon, surveillance to assess long-term stability of occlusion is clearly important. This study evaluated unenhanced and contrast-enhanced transcranial color-coded duplex sonography (TCCS) in detecting refilling of IAs treated with detachable coils. METHODS: Patients with coiled IAs were imaged before and after contrast enhancement. The results were compared with those of a surveillance digital subtraction angiogram (DSA). The operator was blinded to the results of the DSA. Aneurysms were classed as either occluded or with residual flow and quantified as minor, moderate, or extensive. There were 208 studies performed in 4 neurosurgical centers. Of those, 141 studies received ultrasonic contrast enhancement with Levovist, and 68 had an additional enhanced study with SonoVue. RESULTS: We excluded 44 studies. Of the 164 unenhanced studies, TCCS correctly identified 52 of 67 cases defined as completely occluded by DSA (sensitivity 78%; specificity 77%), 13 of 50 aneurysms with minor refilling (sensitivity 26%; specificity 88%), 15 of 27 aneurysms with moderate refilling (sensitivity 56%; specificity 95%), and 9 of 20 aneurysms with extensive refilling (sensitivity 45%; specificity 100%). TCCS correctly identified an additional 10 aneurysms with minor refilling after Levovist enhancement and 3 with SonoVue. Both SonoVue and Levovist enhancement identified an additional 1 aneurysm with moderate refilling and 3 with extensive refilling. CONCLUSIONS: TCCS could be used to selectively monitor IAs, which would reduce the requirement for long-term invasive monitoring. The detection of neck refilling is improved with contrast enhancement.