Unconstrained quantitative magnetization transfer imaging: disentangling T1 of the free and semi-solid spin pools.

Since the inception of magnetization transfer (MT) imaging, it has been widely assumed that Henkelman's two spin pools have similar longitudinal relaxation times, which motivated many researchers to constrain them to each other. However, several recent publications reported a T1s of the semi-solid spin pool that is much shorter than T1f of the free pool. While these studies tailored experiments for robust proofs-of-concept, we here aim to quantify the disentangled relaxation processes on a voxel-by-voxel basis in a clinical imaging setting, i.e., with an effective resolution of 1.24mm isotropic and full brain coverage in 12min. To this end, we optimized a hybrid-state pulse sequence for mapping the parameters of an unconstrained MT model. We scanned four people with relapsing-remitting multiple sclerosis (MS) and four healthy controls with this pulse sequence and estimated T1f≈1.84s and T1s≈0.34s in healthy white matter. Our results confirm the reports that T1s≪T1f and we argue that this finding identifies MT as an inherent driver of longitudinal relaxation in brain tissue. Moreover, we estimated a fractional size of the semi-solid spin pool of m0s≈0.212, which is larger than previously assumed. An analysis of T1f in normal-appearing white matter revealed statistically significant differences between individuals with MS and controls.

Rapid quantitative magnetization transfer imaging: Utilizing the hybrid state and the generalized Bloch model.

PURPOSE: To explore efficient encoding schemes for quantitative magnetization transfer (qMT) imaging with few constraints on model parameters. THEORY AND METHODS: We combine two recently proposed models in a Bloch-McConnell equation: the dynamics of the free spin pool are confined to the hybrid state, and the dynamics of the semi-solid spin pool are described by the generalized Bloch model. We numerically optimize the flip angles and durations of a train of radio frequency pulses to enhance the encoding of three qMT parameters while accounting for all eight parameters of the two-pool model. We sparsely sample each time frame along this spin dynamics with a three-dimensional radial koosh-ball trajectory, reconstruct the data with subspace modeling, and fit the qMT model with a neural network for computational efficiency. RESULTS: We extracted qMT parameter maps of the whole brain with an effective resolution of 1.24 mm from a 12.6-min scan. In lesions of multiple sclerosis subjects, we observe a decreased size of the semi-solid spin pool and longer relaxation times, consistent with previous reports. CONCLUSION: The encoding power of the hybrid state, combined with regularized image reconstruction, and the accuracy of the generalized Bloch model provide an excellent basis for efficient quantitative magnetization transfer imaging with few constraints on model parameters.

Effectiveness of subcutaneous tocilizumab in neuromyelitis optica spectrum disorders.

BACKGROUND: Tocilizumab (TCZ), a humanized monoclonal antibody against the interleukin-6 receptor, is approved for treatment of rheumatoid arthritis and several other immune-mediated disorders. Off-label use of the intravenous formulation of tocilizumab for Neuromyelitis Optica Spectrum Disorder (NMOSD) decreased relapse rates in two small case series. However, treatment protocol that requires frequent intravenous infusions may adversely affect adherence to therapy, especially in the more disabled patients, thereby reducing effectiveness. A subcutaneous formulation of tocilizumab was shown to be noninferior to the IV formulation for approved rheumatologic diseases. The effectiveness of subcutaneous TCZ for NMOSD is unknown. METHODS: We retrospectively reviewed clinical, radiological and serological data on all NMOSD patients who received subcutaneous TCZ in two tertiary referral centers between 2014-2019. RESULTS: Twelve NMOSD patients who received at least 6 months of subcutaneous TCZ were identified. Eleven were female; mean age was 46.9 ± 14.5 years and mean disease duration was 6.6 ± 4.6 years. Seven patients were seropositive for AQP-4 antibodies, two - for MOG-IgG antibodies, and three were doubly seronegative. During subcutaneous TCZ treatment, eight patients (66.6%) were relapse-free, one patient (8.3%) experienced 1 relapse, two patients (16.6%) - 2 relapses, and one patient (8.3%) - 3 relapses. The median relapse rate within 1 year after starting subcutaneous TCZ - 0 (interquartile range =1.75-0) - was significantly lower than in the year prior to treatment initiation (2, interquartile range = 4.0-0.25; p = 0.04). Overall, the annual relapse rate (ARR) decreased from a median of 2 (interquartile range = 5.75-1.29) prior to subcutaneous TCZ to 0 (interquartile range= = 1.0-0) on treatment (p = 0.0015). One TCZ-treated patient died following a severe myelitis attack. CONCLUSIONS: Effectiveness of subcutaneous TCZ in NMOSD appears to be similar to that reported for the IV formulation and has an advantage of at-home administration. Prospective, comparative studies of subcutaneous TCZ for NMOSD are warranted.

Progressive myelopathy associated with spinal epidural lipomatosis in three non-obese patients with type 1 diabetes mellitus.

BACKGROUND: Spinal epidural lipomatosis (SEL) is a rare condition defined as pathological overgrowth of the normally present epidural fat within the spinal canal. SEL is associated with Cushing disease, obesity and chronic corticosteroid therapy. Diabetes mellitus type 1 (DM1) has not known to be a risk factor for SEL. The neurological symptoms of SEL are attributed mainly to mechanical compression on the spinal cord and the cauda equina. METHODS: A retrospective chart review of patients evaluated at NYU Multiple Sclerosis Care Center identified three diabetic patients with progressive myelopathy associated with SEL. We report the clinical course, diagnostic workup and outcomes in these three patients with SEL-associated myelopathy. RESULTS: Three patients (2 females and 1 male) had long-standing DM1 and developed progressive myelopathy in their early 40's. All were found to have thoracic SEL (extensive extradural T1, T2 hyperintense signal; biopsy confirmed in one case) with associated extensive abnormal cord signal in lower cervical/upper thoracic spinal cord. A comprehensive evaluation for metabolic, infectious, autoimmune and vascular causes of myelopathy that included serologies, cerebrospinal fluid analyses, and spinal angiography did not reveal an alternative cause for myelopathy. One of the patients underwent a surgical decompression of SEL with subsequent clinical and radiologic improvement. CONCLUSIONS: Our case series suggest that patients with DM1 and myelopathy of unknown cause should be evaluated for SEL. Timely diagnosis and appropriate intervention may forestall progression of neurological disability and even result in neurologic improvement. SEL should be considered on the short list of diagnoses that cause potentially reversible progressive myelopathy.

Nocturia in Patients With Multiple Sclerosis.

The prevalence of nocturia in patients with multiple sclerosis (MS) is high, ranging from 20.9% to 48.8% in this population. Its underlying pathophysiology is complex and different from the non-neurogenic population. In the MS population, the pathophysiology may involve neurogenic lower urinary tract dysfunction (NLUTD) such as detrusor overactivity (NDO), detrusor-sphincter dyssynergia, or detrusor underactivity resulting in reduced bladder capacity. Nocturnal polyuria is also a significant contributor to the pathogenesis of nocturia in MS patients and may be the result of specific mechanisms such as nocturnal hypertension through autonomic cardiovascular dysfunction or lack of diurnal variation of antidiuretic hormone production (ADH) due to demyelinating lesions of the spinal cord. Nocturia might be particularly burdensome in MS patients by contributing to fatigue, a common and highly debilitating symptom in this population. There is likely a complex and multidirectional relationship between nocturia, other sleep disorders, and fatigue in the MS population that has yet to be explored. The assessment of nocturia in MS should rely upon a thorough history and physical examination. Urinalysis should be done to rule out urinary tract infection, a frequency-volume chart might help elucidating the underlying mechanisms, and post-void residual volume may be of interest to screen for urinary retention that could be asymptomatic in MS patients. Other tests such as urodynamics or polysomnography are indicated in selected patients. The treatment should be tailored to the underlying cause. The first steps involve behavioral interventions and treatment of cofactors. When possible, the predominant mechanism should be addressed first. In case of predominant NDO, antimuscarinics and beta-3 agonists should be offered as a first-line treatment and intradetrusor injections of botulinum toxin as a second-line treatment. In cases of incomplete bladder emptying, clean-intermittent self-catheterization is often used as part of multiple other interventions. In cases of nocturnal polyuria, desmopressin may be offered, inclusive of use of newer formulations (desmopressin acetate nasal spray, desmopressin orally disintegrated tablet) in countries where they are approved.

Hemicrania continua.

In recent years, hemicrania continua has become a well-recognized primary headache disorder known for its chronicity and resulting disability in a subset of patients with headache. The core clinical features have been well described: unilateral, side-locked headaches that are continuous (although interrupted by frequent severe exacerbations), associated with autonomic symptoms and a response to indomethacin. However, areas of relative controversy remain in its classification and diagnosis. Several relatively large case series have better delineated the associated features of this disorder, including atypical presentations. Recently, neuroimaging research has provided new insights into the underlying pathways involved in the disorder, in particular activation of the contralateral posterior hypothalamus and the ipsilateral dorsal rostral pons. Despite its well-known response to indomethacin, many patients still endure long delays in the appropriate diagnosis and treatment. There remains a need for new treatments given the morbidity associated with long-term indomethacin use.

A review of cognitive therapy in acute medical settings. Part II: strategies and complexities.

OBJECTIVE: Cognitive therapy (CT) has considerable utility for psychosomatic medicine (PM) in acute medical settings but, to date, no such cohesive adaptation has been developed. Part I delineated a CT model for acute medical settings focusing on assessment and formulation. In Part II, we review how CT can be applied to common PM clinical challenges. A pragmatic approach is helpful because this review targets PM trainees and educators. METHODS: Narrative review is used to discuss the application of CT strategies to common challenges in acute medical settings. Treatment complexities and limitations associated with the PM setting are detailed. Exemplary dialogues are used to model techniques. RESULT: We present CT approaches to eight common scenarios: (1) distressed or hopeless patients; (2) patients expressing pivotal distorted cognitions/images; (3) patients who catastrophize; (4) patients who benefit from distraction and activation strategies; (5) panic and anxiety; (6) suicidal patients; (7) patients who are stuck and helpless; (8) inhibited patients. Limitations are discussed. SIGNIFICANCE OF RESULTS: A CT informed PM assessment, formulation and early intervention with specific techniques offers a novel integrative framework for psychotherapy with the acutely medically ill. Future efforts should focus on dissemination, education of fellows and building research efficacy data.