Clarithromycin-Induced Visual Hallucinations.

An independent 90-year-old woman presented to hospital with vivid and dynamic visual hallucinations following initiation of clarithromycin therapy. She had a background of previous cataract removal with good visual resolution and no significant deficits in visual acuity. Notably, she had been taking sertraline and quinine concurrently. Her symptoms fully resolved 72 hours following cessation of clarithromycin therapy. Visual hallucinations associated with clarithromycin could be explained by recent research demonstrating clarithromycin increases neuronal excitability by inhibiting gamma-aminobutyric acid-ergic signalling. Case reports of similar nature are rare, and we believe this report adds to a currently growing body of literature of visual hallucinations as a side effect of clarithromycin.

A Case of New Onset Cervical Dystonia in Pregnancy.

Background: Though uncommon, primary movement disorders can occur in pregnancy, the most common being restless legs syndrome and chorea gravidarum [1]. New onset dystonia in pregnancy has been reported four times previously with a resolution of symptoms within six months of delivery [2345]. Exacerbation of pre-existing movement disorders and the onset of de novo movement disorders during pregnancy support the hypothesis that female sex hormones play an important role in the regulation of basal ganglia circuitry. Case Report: Here we describe a case of new-onset cervical dystonia during pregnancy with persistence of symptoms after delivery. Discussion: The phenotypic overlap between this case and previously reported cases further establishes dystonia gravidarum as a distinct clinical entity.

Antibodies to the Caspr1/contactin-1 complex in chronic inflammatory demyelinating polyradiculoneuropathy.

Previous studies have described the clinical, serological and pathological features of patients with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) and antibodies directed against the paranodal proteins neurofascin-155, contactin-1 (CNTN1), contactin-associated protein-1 (Caspr1), or nodal forms of neurofascin. Such antibodies are useful for diagnosis and potentially treatment selection. However, antibodies targeting Caspr1 only or the Caspr1/CNTN1 complex have been reported in few patients with CIDP. Moreover, it is unclear if these patients belong to the same pathophysiological subgroup. Using cell-based assays in routine clinical testing, we identified sera from patients with CIDP showing strong membrane reactivity when both CNTN1 and Caspr1 were co-transfected (but not when CNTN1 was transfected alone). Fifteen patients (10 male; aged between 40 and 75) with antibodies targeting Caspr1/CNTN1 co-transfected cells were enrolled for characterization. The prevalence of anti-Caspr1/CNTN1 antibodies was 1.9% (1/52) in the Sant Pau CIDP cohort, and 4.3% (1/23) in a German cohort of acute-onset CIDP. All patients fulfilled European Federation of Neurological Societies/Peripheral Nerve Society (EFNS/PNS) definite diagnostic criteria for CIDP. Seven (47%) were initially diagnosed with Guillain-Barré syndrome due to an acute-subacute onset. Six (40%) patients had cranial nerve involvement, eight (53%) reported neuropathic pain and 12 (80%) ataxia. Axonal involvement and acute denervation were frequent in electrophysiological studies. Complete response to intravenous immunoglobulin was not observed, while most (90%) responded well to rituximab. Enzyme-linked immunosorbent assay (ELISA) and teased nerve fibre immunohistochemistry confirmed reactivity against the paranodal Caspr1/CNTN1 complex. Weaker reactivity against Caspr1 transfected alone was also detected in 10/15 (67%). Sera from 13 of these patients were available for testing by ELISA. All 13 samples reacted against Caspr1 by ELISA and this reactivity was enhanced when CNTN1 was added to the Caspr1 ELISA. IgG subclasses were also investigated by ELISA. IgG4 was the predominant subclass in 10 patients, while IgG3 was predominant in other three patients. In conclusion, patients with antibodies to the Caspr1/CNTN1 complex display similar serological and clinical features and constitute a single subgroup within the CIDP syndrome. These antibodies likely target Caspr1 primarily and are detected with Caspr1-only ELISA, but reactivity is optimal when CNTN1 is added to Caspr1 in cell-based assays and ELISA.

On the Emergence of Tremor in Prodromal Parkinson's Disease.

Clinical, neuropathological and neuroimaging research suggests that pathological changes in Parkinson's disease (PD) start many years before the emergence of motor signs. Since disease-modifying treatments are likely to be most effective when initiated early in the disease process, there has been significant interest in characterizing prodromal PD. Some people with PD describe autonomic symptoms at the time of diagnosis suggesting that autonomic dysfunction is a common feature of prodromal PD. Furthermore, subtle motor signs may be present and emerge prior to the time of diagnosis. We present a series of patients who, in the prodromal phase of PD, experienced the emergence of tremor initially only while yawning or straining at stool and discuss how early involvement of autonomic brainstem nuclei could lead to these previously unreported phenomena. The hypothalamic paraventricular nucleus (PVN) plays a central role in autonomic control including bowel/bladder function, cardiovascular homeostasis and yawning and innervates multiple brainstem nuclei involved in autonomic functions (including brainstem reticular formation, locus ceruleus, dorsal raphe nucleus and motor nucleus of the vagus). The PVN is affected in PD and evidence from related phenomena suggest that the PVN could increase tremor either by increasing downstream cholinergic activity on brainstem nuclei such as the reticular formation or by stimulating the locus ceruleus to activate the cerebellothalamocortical network via the ventrolateral nucleus of the thalamus. Aberrant cholinergic/noradrenergic transmission between these brainstem nuclei early in PD couldlead to tremor before the emergence of other parkinsonian signs, representing an early clinical clue to prodromal PD.

Harlequin Syndrome in Acute Thalamic Hemorrhage.

Harlequin syndrome is a disorder of the autonomic nervous system. It clinically presents as a distinct line of hemifacial sympathetic denervation. We describe a case of Harlequin syndrome with co-existing central first-order Horner syndrome in the setting of a large thalamic hemorrhage with intraventricular extension.

Ryanodine receptor 2 (RYR2) mutation: A potentially novel neurocardiac calcium channelopathy manifesting as primary generalised epilepsy.

PURPOSE: Ryanodine receptor 2 (RYR2) mutation is well-established in the aetiology of an inherited cardiac disorder known as catecholaminergic polymorphic ventricular tachycardia (CPVT). The RYR2 receptor is expressed in cardiomyocytes, and also in the hippocampus. The RYR2 mutation has not been reported as a potential cause of adult-onset genetic generalised epilepsy (GGE). METHOD: Case report. RESULTS: A 32-year-old right-handed female presented with three unprovoked generalised seizures over twelve years. Electroencephalogram showed epileptiform activity which coincided with normal electrocardiogram recording. Her brother survived a cardiac arrest in his 20's and was diagnosed with CPVT and found to be heterozygous for a novel mutation in the RYR2 gene at chromosome 1q43, c.229 G > A p.(Ala77Thr). The patient inherited the same missense variant, predicted to be damaging by numerous in silico analytic tools. This mutation affects the N-terminal domain of the RYR2 receptor which plays a role in channel activation. However, the patient had repeatedly normal cardiac investigations including normal exercise stress tests. CONCLUSION: We propose that the RYR2 mutation is a potentially novel neurocardiac calcium channelopathy that may manifest with either CPVT or GGE depending on selective involvement of RYR2 receptors expressed in the heart or in the brain. RYR2 mutant mice have demonstrated spontaneous EEG-positive seizures independent of cardiac arrhythmia. Whole exome sequencing analyses have identified RYR2 as a candidate gene in GGE. This case is a reminder for careful assessment of episodes of transient loss of consciousness in an individual with CPVT, so as to not mistake possible neurogenic seizure for cardiogenic syncope, carrying obvious implications for treatment.

Aciclovir-induced acute kidney injury in patients with 'suspected viral encephalitis' encountered on a liaison neurology service.

BACKGROUND: Patients with 'suspected viral encephalitis' are frequently empirically treated with intravenous aciclovir. Increasing urea and creatinine are 'common', but rapidly progressive renal failure is reported to be 'very rare'. AIMS: To describe the clinical course and outcome of cases of aciclovir-induced acute kidney injury (AKI) encountered by the Liaison Neurology Service at AMNCH and to highlight the importance of surveillance and urgent treatment of this iatrogenic complication. METHODS: Retrospectively and prospectively collected data from the Liaison Neurology Service at AMNCH on patients who received IV aciclovir for suspected viral encephalitis and developed AKI were analysed. Aciclovir-induced AKI was defined by a consultant nephrologist in all cases as a rise in serum creatinine of > 26 µmol/L in 48 h or by ≥ 1.5 times the baseline value. Renal function, haematocrit, and fluid balance were monitored following AKI onset. RESULTS: Data from 10 patients were analysed. Median time to AKI onset was 3.5 days (range: 1-6 days). Aciclovir was stopped or the dose adjusted. All patients recovered with IV normal saline, aiming for a urine output > 100-150 ml/h. The interval between first rise in creatinine and return to normal levels varied between 5 and 19 days. CONCLUSIONS: Liaison neurologists and general physicians need to be aware that aciclovir may cause AKI attributed to distal intra-tubular crystal nephropathy. Daily fluid balance and renal function monitoring are essential because AKI may arise even with intensive pre-hydration. Prognosis is good if identified early and actively treated.

Frequent inaccuracies in ABCD2 scoring in non-stroke specialists' referrals to a daily Rapid Access Stroke Prevention service.

The 'accuracy' of age, blood pressure, clinical features, duration and diabetes (ABCD(2)) scoring by non-stroke specialists referring patients to a daily Rapid Access Stroke Prevention (RASP) service is unclear, as is the accuracy of ABCD(2) scoring by trainee residents. In this prospective study, referrals were classified as 'confirmed TIAs' if the stroke specialist confirmed a clinical diagnosis of possible, probable or definite TIA, and 'non-TIAs' if patients had a TIA mimic or completed stroke. ABCD(2) scores from referring physicians were compared with scores by experienced stroke specialists and neurology/geriatric medicine residents at a daily RASP clinic; inter-observer agreement was examined. Data from 101 referrals were analysed (mean age=60.0years, 58% male). The median interval between referral and clinic assessment was 1day. Of 101 referrals, 52 (52%) were 'non-TIAs': 45 (86%) of 52 were 'TIA mimics' and 7 (14%) of 52 were completed strokes. There was only 'fair' agreement in total ABCD(2) scoring between referring physicians and stroke specialists (κ=0.37). Agreement was 'excellent' between residents and stroke specialists (κ=0.91). Twenty of 29 patients scored as 'moderate to high risk' (score 4-6) by stroke specialists were scored 'low risk' (score 0-3) by referring physicians. ABCD(2) scoring by referring doctors is frequently inaccurate, with a tendency to underestimate stroke risk. These findings emphasise the importance of urgent specialist assessment of suspected TIA patients, and that ABCD(2) scores by non-stroke specialists cannot be relied upon in isolation to risk-stratify patients. Inter-observer agreement in ABCD(2) scoring was 'excellent' between residents and stroke specialists, indicating short-term training may improve accuracy.

Comparison of sudomotor and sensory nerve testing in painful sensory neuropathies.

OBJECTIVE: To compare results of quantitative sudomotor axon reflex testing (QSART), dorsal sural, and sural sensory nerve testing in patients with painful sensory neuropathy (PSN). METHODS: Fifty-six patients with symptoms and neurologic examinations consistent with PSN who had both autonomic and nerve conduction studies were identified from 376 patients with a clinical diagnosis of painful neuropathy. Cases were clinically categorized as large-fiber or small-fiber neuropathies by described criteria. The results of sural, dorsal sural, and QSART tests were then analyzed in relationship to these two clinical groups. RESULTS: Evidence of unmyelinated fiber abnormalities by QSART was noted in 85% of clinical large-fiber and 69% of clinical small-fiber groups. Dorsal sural potentials were absent in all the large-fiber group but also in 52% of clinically classified small-fiber neuropathies. When QSART and dorsal sural abnormalities were combined, the identification of abnormalities in all the cases of PSN was 89% with 75% of cases (42) showing mixed large and small fiber abnormalities, 14% unmyelinated sensory fiber abnormalities (by QSART), and 11% normal studies. CONCLUSION: This study demonstrates the value of combining both QSART and dorsal sural sensory testing in verifying the diagnosis of PSN. The majority of cases demonstrate involvement of unmyelinated C fibers as well as large/medium myelinated fibers, thereby separating mixed large- and small-fiber sensory neuropathies from those cases classified by clinical criteria solely as small-fiber neuropathy.

Coincident membranous glomerulonephritis and chronic inflammatory demyelinating polyradiculoneuropathy: questioning the autoimmunity hypothesis.

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) and membranous glomerulonephritis (MGN) are both autoimmune disorders that are rarely observed concurrently. We describe a patient who developed MGN nearly 20 years after the onset of CIDP, resulting in a secondary progression of his neuropathy. He responded dramatically to a novel regimen of plasma exchange and methotrexate. We propose a mechanism other than autoimmunity for the coincidence of these disorders and discuss the theoretical superiority of the treatment regimen that he received.