Dorsal midbrain syndrome in multiple sclerosis with magnetic resonance imaging correlation

Temperature sensitivity in multiple sclerosis: An overview of its impact on sensory and cognitive symptoms

Multiple sclerosis (MS) is an autoimmune neurodegenerative disease characterized by demyelination of the central nervous system (CNS). The exact cause of MS is still unknown; yet its incidence and prevalence rates are growing worldwide, making MS a significant public health challenge. The heterogeneous distribution of demyelination within and between MS patients translates in a complex and varied array of autonomic, motor, sensory and cognitive symptoms. Yet a unique aspect of MS is the highly prevalent (60-80%) temperature sensitivity of its sufferers, where neurological symptoms are temporarily exacerbated by environmental- or exercise-induced increases (or decreases) in body temperature. MS temperature sensitivity is primarily driven by temperature-dependent slowing or blocking of neural conduction within the CNS due to changes in internal (core) temperature; yet changes in skin temperature could also contribute to symptom exacerbation (e.g. during sunlight and warm ambient exposure). The impact of temperature sensitivity, and particularly of increases in core temperature, on autonomic (e.g. thermoregulatory/cardiovascular function) and motor symptoms (e.g. fatigue) is well described. However, less attention has been given to how increases (and decreases) in core and skin temperature affect sensory and cognitive symptoms. Furthermore, it remains uncertain whether changes in skin temperature alone could also trigger worsening of symptoms. Here we review the impact of temperature sensitivity on MS sensory and cognitive function and discuss additional factors (e.g. changes in skin temperature) that potentially contribute to temperature-induced worsening of symptoms in the absence of alteration in core temperature.

Parinaud's syndrome due to an unilateral vascular ischemic lesion

A 59-year-old man who complained of binocular vertical diplopia after an exploratory laparotomy, complicated by cardiorespiratory arrest during anesthetic induction, was found to have Collier's sign, anisocoria, complete paralysis of upward vertical gaze associated with convergence-retraction nystagmus on attempted upgaze and skew deviation with hypertropia in the left eye without ptosis, and an absent Bielschowsky sign. Magnetic resonance imaging of the brain showed a small lesion in the left paramedian midbrain compatible with microvascular ischemic sequelae. This patient was diagnosed with Parinaud's syndrome (dorsal midbrain syndrome) associated with a vertical strabismus from an unilateral vascular ischemic paramedian midbrain lesion.

Sylvian aqueduct syndrome and global rostral midbrain dysfunction associated with shunt malfunction

OBJECT

This study is a retrospective analysis of clinical data obtained in 28 patients affected by obstructive hydrocephalus who presented with signs of midbrain dysfunction during episodes of shunt malfunction.

METHODS

All patients presented with an upward gaze palsy, sometimes associated with other signs of oculomotor dysfunction. In seven cases the ocular signs remained isolated and resolved rapidly after shunt revision. In 21 cases the ocular signs were variably associated with other clinical manifestations such as pyramidal and extrapyramidal deficits, memory disturbances, mutism, or alterations in consciousness. Resolution of these symptoms after shunt revision was usually slow. In four cases a transient paradoxical aggravation was observed at the time of shunt revision. In 11 cases ventriculocistemostomy allowed resolution of the symptoms and withdrawal of the shunt. Simultaneous supratentorial and infratentorial intracranial pressure recordings performed in seven of the patients showed a pressure gradient between the supratentorial and infratentorial compartments, with a higher supratentorial pressure before shunt revision. Inversion of this pressure gradient was observed after shunt revision and resolution of the gradient was observed in one case after third ventriculostomy. In six recent cases, a focal midbrain hyperintensity was evidenced on T2-weighted magnetic resonance imaging sequences at the time of shunt malfunction. This rapidly resolved after the patient underwent third ventriculostomy.

CONCLUSIONS

It is probable that in obstructive hydrocephalus, at the time of shunt malfunction, the development of a transtentorial pressure gradient could initially induce a functional impairment of the upper midbrain, inducing upward gaze palsy. The persistence of the gradient could lead to a global dysfunction of the upper midbrain. Third ventriculostomy contributes to equalization of cerebrospinal fluid pressure across the tentorium by restoring free communication between the infratentorial and supratentorial compartments, resulting in resolution of the patient's clinical symptoms.

Retraction-convergence nystagmus: clinical and radiological study of 4 cases of vascular origin

Retraction-convergence nystagmus is a classic finding in extensive and bilateral lesions of the dorsal midbrain, usually neoplastic and, as such, considered to signal a poor prognosis. We report 4 cases of retraction-convergence nystagmus associated with Parinaud syndrome arising from circumscribed lesions of vascular origin--3 hemorrhagic and 1 ischemic--with a completely benign course. The neuroimaging study enabled us to identify involvement of the pretectal areas and posterior commissure as well as of the dorsomedial thalamic nuclei in all cases. It thus seems that one or more of these areas must be involved in the genesis of this nystagmus.

One-year MR imaging follow-up of patients with multiple sclerosis under cortisone therapy

Twenty patients with relapsing/remitting course of MS were studied four times with MR imaging over the course of one year. First MR was undertaken during the acute relapse, afterwards patients were given cortisone therapy for four to six weeks. The second MR study followed 4-6 weeks after the first, the patients at this time being in remission. The third MR study was carried out 4 months after the first, the last scan one year after the first. The total number of lesions varied, though not greatly, over the whole follow-up, but there was an influence of the clinical course of MS on the pattern of lesions in MR imaging, mostly in respect to the number of confluences and the size of the lesions. Follow-up over one year showed that the inflammatory process produced an increase in the number of plaques, independent of the fact that most patients stayed in remission. A delayed effect of the cortisone therapy on the size, number, and confluence of plaques is suggested whilst clinical signs improved in most cases immediately after the beginning of drug therapy. Independent of the clinical course of the disease in some cases plaques previously seen vanished and others appeared in one and the same examination.

Serial magnetic resonance scanning in multiple sclerosis: a second prospective study in relapsing patients

A prospective study of serial magnetic resonance (MR) scans of the brain was carried out every 2 weeks for 4 to 6 months in 9 patients with mild, clinically definite, relapsing/remitting multiple sclerosis (MS). Six of the 9 patients developed a total of 12 asymptomatic new lesions in various parts of the brain. In none of the patients were the changes on MR scan accompanied by relevant new neurological symptoms or signs. New MR lesions had a characteristic temporal profile, reaching a maximum size in approximately 4 weeks before gradually shrinking, usually leaving a small residual abnormality indistinguishable from chronic MS lesions. The frequent occurrence of new asymptomatic lesions indicates that MS may be a more active process even in mildly affected asymptomatic patients than has been previously realized. The results emphasize the potential importance of using MR scanning to measure disease activity in laboratory studies of MS and in the assessment of treatment, particularly in asymptomatic patients in the early stages. We suggest that the expanding and contracting new lesions are the basic or primary lesion in MS, that the characteristic demyelinated plaque is represented by the small residual area that these lesions shrink down to, and that the typical collection of scattered white matter lesions in chronic MS may represent the accumulated residua of dozens or more of these active lesions occurring over many years.

Magnetic resonance imaging in the evaluation of treatment in multiple sclerosis

Magnetic resonance scans of 74 patients with multiple sclerosis participating in a controlled trial were compared 6 months before and at the end of a 24-32 months-treatment period with either Cyclosporin A (n = 31) or Azathioprine (n = 43). Both qualitative rating and computation of lesion volume showed deterioration in more than 40% of the patients, while by clinical criteria only 10-30% were worse. No significant difference was noted when the two treatment groups were compared. If careful repositioning and standardized image parameters are used, MRI is an indispensable tool for the objective determination of disease progression in MS although it cannot replace clinical examination.