Pattern ERGs suggest a possible retinal contribution to the visual acuity loss in acute optic neuritis.

PURPOSE: Macular involvement in optic neuritis (ON) is well-recognised but poorly understood and may be of clinical relevance. This study explores macular structure-function correlates in acute ON. METHODS: This cross-sectional cohort study recruited ON patients within 14 days of symptom onset. Subjects underwent pattern electroretinography (PERG), pattern visual evoked potentials (PVEP) and optical coherence tomography (OCT) imaging. PERG P50 and N95 components were correlated with OCT data. RESULTS: Twenty-six individuals with ON were recruited, comprising eleven multiple sclerosis (MS-ON), six myelin oligodendrocyte glycoprotein associated (MOG-ON) and nine with isolated ON. These were compared with 28 healthy controls. PVEPs were undetectable in 11 (42%) of individuals with ON. When detectable, PVEP P100 was delayed (median 136 ms range 110-173 ms) and amplitude reduced (median 6 µV, range 3-14 µV) in ON compared with controls (both p < 0.001). PERG P50 component amplitudes, largely reflecting macular function, were reduced in affected eyes (median 2.3 µV; range 0.8-5.0 µV) compared with controls (3.3 µV; range 2.8-5.7 µV) and compared with fellow eyes (p < 0.001). The N95:P50 ratio was below the reference range in the affected eyes of five patients. Eight cases (32%) had subnormal P50 amplitudes (< 2.0 µV), and these patients had poorer visual acuity (p = 0.020). P50 amplitudes were positively correlated with an increase in inner nuclear layer thickness (rs = 0.36; p = 0.009) and macular ganglion cell and inner plexiform layer (mGCIPL) thickness (rs = 0.44, p = 0.022). CONCLUSION: PERG P50 component reduction reveals dysfunction of inner macular layers in acute ON and correlates with structural alterations on OCT. These early macular pathologic processes are likely to contribute to the visual loss.

Pneumonitis secondary to alemtuzumab in a patient with multiple sclerosis - A non-infectious cause of breathlessness.

The most common adverse events associated with the monoclonal antibody alemtuzumab are infusion associated reactions and secondary autoimmune disease. Respiratory complications are unusual following treatment with alemtuzumab, but can be precipitated by an infectious cause. We describe a case of a sub-acute steroid responsive non-infectious pneumonitis affecting a 51 year old woman, who presented one month after initiation of therapy for multiple sclerosis with alemtuzumab.

Neuromyelitis optica spectrum disorder related tonic spasms responsive to lacosamide.

Paroxysmal tonic spasms [PTS] are common in patients with neuromyelitis optica spectrum disorder (NMOSD).1 2 In patients with demyelinating disease, PTS can significantly reduce the quality of life, limit activities of daily living and the rehabilitative process following an acute relapse 3. As in patients with multiple sclerosis (MS), paroxysmal tonic spasms in NMOSD usually respond well to treatment with carbamazepine.2 However, the optimal treatment in patients where carbamazepine is contraindicated or poorly tolerated is unclear. We describe a patient with NMOSD with severe paroxysmal tonic spasms who did not tolerate carbamazepine but was successfully treated with lacosamide (Vimpat).

Antecedent anti-NMDA receptor encephalitis in two patients with multiple sclerosis.

Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is an autoimmune disorder characterised by psychiatric symptoms, movement disorder and seizures often evolving into a severe encephalopathy. An overlap has recently been recognised between anti-NMDAR encephalitis and inflammatory demyelinating disorders, particularly neuromyelitis optical spectrum disorder (NMOSD). In this case report, we describe two patients with an initial presentation consistent with anti-NMDAR encephalitis who have subsequently developed relapsing-remitting multiple sclerosis (MS) and discuss the literature pertaining to potential overlap between NMDAR encephalitis and inflammatory demyelinating disorders.

A preliminary longitudinal study of the retinal nerve fiber layer in progressive multiple sclerosis.

Thinning of the retinal nerve fiber layer (RNFL) of clinically unaffected eyes is seen in patients with multiple sclerosis (MS). It is uncertain when this thinning occurs, and whether ongoing RNFL loss can be measured over time with optical coherence tomography (OCT). Using time-domain OCT, we studied 34 patients with progressive MS (16 primary progressive MS, 18 secondary progressive; 14 male; 20 female; mean age at study entry 51 years; median EDSS 6; mean disease duration at study entry 12 years) on two occasions with a median interval of 575 (range 411-895) days apart. Eighteen healthy controls (10 male; eight female; mean age at study entry 46 years) were also studied twice, with a median interval of 656 days (range 398-890). Compared to controls, the patients had significant decreases in the RNFL thickness and macular volume of their clinically unaffected eyes at study entry. No significant decrease in RNFL thickness was observed between baseline and follow-up in either patients or controls. Macular volume declined significantly in patients and controls, but there was no difference in this change between the two groups. The study findings suggest that time domain OCT detects little disease-related ongoing loss of retinal axons in progressive forms of MS and has limited use for monitoring potential neuroprotective therapies at this stage of disease. Further studies are needed using higher-resolution OCT systems and in larger groups of patients, to elucidate the timing and mechanism of RNFL loss that is observed in clinically unaffected nerves in MS.

Optic nerve magnetization transfer imaging and measures of axonal loss and demyelination in optic neuritis.

Magnetization transfer imaging is an MRI technique that provides quantitative information about in vivo tissue integrity, including myelin and axonal content, and is expressed as the magnetization transfer ratio (MTR). The optic neuritis lesion can model the MS lesion in vivo and permits use of non-invasive markers of optic nerve myelination (visual evoked potential [VEP] latency) and retinal neuroaxonal loss (optical coherence tomography [OCT]) to provide further information about the in vivo substrates of optic nerve MTR. Twenty-five patients with optic neuritis were studied using an optic nerve MTR sequence, quantitative visual function testing, VEPs and OCT, along with 15 controls. MTR was reduced in affected nerves compared to both clinically unaffected nerves from patients and control nerves (P < 0.001). Whole-nerve MTR correlated modestly with central-field VEP latency but more strongly when lesion-only MTR was measured, when a modest correlation with whole-field VEP latency emerged. OCT-quantified retinal neuroaxonal loss also correlated with MTR. In conclusion, markers of optic nerve myelination and axonal loss both correlate with optic nerve MTR. Because axonal loss following optic neuritis also results in myelin loss, the relative contributions of the two pathological conditions to the MTR measures cannot be estimated from this study.

In vivo diffusion tensor imaging of the human optic nerve: pilot study in normal controls.

Diffusion tensor imaging (DTI) of the optic nerve (ON) was acquired in normal controls using zonally oblique multislice (ZOOM) DTI, which excites a small field of view (FOV) using a fast sequence with a shortened EPI echo train. This combines the benefit of low sensitivity to motion (due to the single-shot acquisition used), with the additional advantage of reduced sensitivity to magnetic field susceptibility artifacts. Reducing the bright signal from the fat and cerebrospinal fluid (CSF) surrounding the nerve are key requirements for the success of the presented method. Measurements of mean diffusivity (MD) and fractional anisotropy (FA) indices were made in a coronal section of the middle portion of the optic nerve (ON) in the right (rON) and left (lON) ONs. The average values across 10 healthy volunteers were FArON = 0.64 +/- 0.09 and FAlON = 0.57 +/- 0.10, and MDrON = (1173 +/- 227) x 10(-6) mm2 s(-1) and MDlON = (1266 +/- 170) x 10(-6) mm2 s(-1). Measurements of the principal eigenvalue of the DT and its orthogonal component were also in agreement with those expected from a highly directional structural organization.

Quantification of optic nerve head topography in optic neuritis: a pilot study.

AIMS: To investigate optic nerve head topography in patients with optic neuritis compared to controls using the Heidelberg retina tomograph-II (HRT-II) and to determine if detected changes are related to visual function and electrophysiology. METHODS: 25 patients with a previous single episode of unilateral optic neuritis and 15 controls were studied with HRT-II, visual evoked potentials, and pattern electroretinogram. Patients also had testing of visual acuity, visual field, and colour vision. RESULTS: In affected eyes compared to fellow eyes, there was reduction of both the mean retinal nerve fibre layer (RNFL) thickness at the disc edge (p = 0.009) and the neuroretinal rim volume (p = 0.04). In affected eyes compared to control eyes, the three dimensional optic cup shape measure was increased (p = 0.01), indicative of an abnormal cup shape. There were no other significant differences in HRT-II measures. Within patient interocular difference correlation was used to investigate the functional relevance of these changes and demonstrated associations between RNFL thickness change and changes in visual acuity, visual field, and colour vision. Colour vision change was also associated with change in neuroretinal rim volume. CONCLUSIONS: HRT detects functionally relevant changes in RNFL thickness and neuroretinal rim volume between eyes affected by optic neuritis and unaffected fellow eyes.

Acetylcholinesterase activity of skeletal muscle in a non-immunogenic model for myasthenia gravis in rats.

Myasthenia gravis is caused by an autoimmune attack to acetylcholine receptors of skeletal muscle. Acetylcholine release from motor nerve terminals is upregulated in patients with myasthenia gravis and also in rat "myasthenic" models, dependent on the reduction of the number of acetylcholine receptors. This study addresses the question as to whether at "myasthenic" endplates there are changes in the activity of acetylcholinesterase. To this end we studied acetylcholinesterase activity in junctional and extrajunctional regions of dilator naris, extensor digitorum longus, and hemidiaphragm muscles from rats with alpha-bungarotoxin-induced myasthenia gravis. In all studied muscles from "myasthenic" rats there was no significant change of junctional acetylcholinesterase activity. In contrast, in dilator naris and extensor digitorum longus muscles, there was a 60% and 30% increase of extrajunctional acetylcholinesterase activity. There was no significant change in the extrajunctional activity in hemidiaphragm muscles. Velocity sedimentation analysis revealed that the increase in extrajunctional activity in extensor digitorum longus muscles could be attributed to an increase of the activity of the G4 form of acetylcholinesterase. Treatment of rats with 6.4 microgh(-1) neostigmine bromide for 29 days had no influence on junctional and extrajunctional acetylcholinesterase activity of extensor digitorum longus muscles from rats with alpha-bungarotoxin-induced myasthenia gravis.