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PubMed2002

[Dysfunction of the magnocellular pathway in Alzheimer's disease].

Visual disturbances are a common feature of Alhzeimer's disease. They are related primarily to visuo-spatial deficits. The pathways mediating visuo-spatial and form identification are at least partially segregated in the brain. The magnocellular pathway has characteristics which make it more suitable for detecting dynamic form, motion and depth. We assessed by means of psychophysical and electrophysiological testings the properties of the parvo and the magnocellular pathways. We found contrast sensitivity deficits for the low and middle spatial frequencies, a significant reduction of the amplitude of the steady-state pattern VEP's at 16, 20 and 24 Hz, abnormal transient pattern VEP's only for the major positivity (P100) and abnormal flash VEP's (delayed P2) as previously observed. The temporal frequency deficits and other abnormalities pointed out in this study, could be related to a dysfunction of the M-pathways in Alzheimer's disease.

Aged↗
PubMed1986

A recessively inherited ataxia with episodes of dystonia.

A family with recessively inherited ataxia and dystonic episodes that responded to antiepileptic medication is described. The onset was in the first decade. Clinically the patients have gait and limb ataxia, nystagmus and brisk reflexes, with abnormal visual, auditory and somatosensory evoked responses, but normal nerve conduction velocities and electromyography. Their intelligence is borderline. CT and MRI scans show severe atrophy in the vermis and basis pontis.

Adolescent↗
PubMed1994

Giant somatosensory evoked potentials and pathophysiology of hyperekplexia. Neurophysiological study of one patient.

EEG during wakefulness and sleep and somatosensory evoked potentials from the median nerve were recorded in a 3 year-old boy with hyperekplexia and his close relatives (parents and two sisters). Centro-temporal spikes during sleep were found in the patient and in the older sister, while somatosensory evoked potentials, in the patient, showed abnormally high amplitude over the centroparietal regions. Pathophysiological mechanisms of hyperekplexia are discussed and the existence of symptomatic forms is suggested.

Child↗
PubMed1994

Parasympathetic autonomic neuropathy in diabetes mellitus: the heart is denervated more often than the pupil.

In one hundred subjects with diabetes mellitus assessed by the techniques of power spectral analysis of heart rate variability and heart rate variability during deep breathing, parasympathetic (vagal) cardiac denervation was shown to occur approximately twice as commonly as parasympathetic pupillary denervation measured by the maximal velocity of pupillary constriction. The pupillary dysfunction was detectable only when both tests of cardiac innervation were abnormal as well. No correlation was found between any of the autonomic measures and duration of known diabetes or degree of metabolic control.

Adolescent↗
PubMed1988

Abnormal oculovestibular response.

In normal individuals, the visual and vestibular systems interact through a common subcortical center located near the vestibular nuclei. When the patient is healthy, this interaction allows appropriate integration of what might otherwise be conflicting information regarding environmental motion and moving within the environment. In patients with active peripheral vestibular lesions, such as those seen in Meniere's disease, this delicate interaction loses effectiveness. In such patients, optokinetic stimuli are capable of precipitating episodes of incapacitating vertigo with its associated vegetative symptoms (abnormal oculovestibular response--AOVR). Since the brainstem is unable to accommodate for active peripheral lesions, suffering may be prolonged for many years. Vestibular nerve section, however, converts this active lesion to a static peripheral lesion, allowing for brainstem compensation and cessation of optokinetic-induced vertiginous symptoms.

Adult↗
PubMed1986

Correlation of 1a afferent conduction with the ataxia of Fisher syndrome.

The pathophysiology of the ataxia in Fisher syndrome (the syndrome of acute ophthalmoplegia, ataxia, and areflexia) has been attributed to both peripheral nervous system pathology and cerebellar system dysfunction. Pathologic studies have demonstrated no consistent central nervous system abnormalities. We present a case in which abnormalities of 1a sensory conduction were found to correlate directly with the degree of ataxia, without impairment of motor or cutaneous sensory conduction. We propose that the ataxia seen in typical Fisher syndrome may be due to demyelination of 1a afferent fibers.

Adult↗
PubMed2005

Referral patterns for common amblyogenic conditions.

PURPOSE: The early detection and management of common pediatric ophthalmic problems is crucial to assure successful visual maturation and best potential for development of binocular vision. The referring physician plays a pivotal role in this process. This study was designed to investigate the prevailing referral patterns for common amblyogenic conditions in a defined geographic region. METHODS: We sent a short questionnaire to 300 pediatricians and 1500 family practitioners (FPs) in Minnesota, asking them to use a multiple choice system to indicate how long after diagnosis they would wait before referring a child to an ophthalmologist for exotropia, esotropia, ptosis, nystagmus, and abnormal red reflex. RESULTS: The response rate was 46.9% ( n = 117) for pediatricians and 17.9% ( n = 240) for FPs. Of respondents, 64.6% of pediatricians and 50.2% of FPs would refer patients with exotropia within 2 months of diagnosis ( P < 0.001). For esotropia, 58.8% of pediatricians would refer within 2 months, while 38.6% would wait up to 12 months. In comparison, 48.7% of FPs would refer sooner, while 47.9% would refer later. These differences in referral patterns for pediatricians and FPs were statistically significant ( P = 0.037). There was less variation for referral of ptosis, nystagmus, and abnormal red reflex. These referral patterns were unaffected by years in practice. CONCLUSIONS: Pediatricians referred patients with strabismus significantly more promptly than FPs. The majority of primary care providers (PCPs) appropriately timed their referrals for these amblyogenic conditions. However, many children continue to be referred late, underscoring the need for continued education of PCPs.

Amblyopia↗
PubMed2002

Minor neurological signs and developmental performance in high risk children at preschool age.

The aim of this study was to establish correlations between minor neurological findings and developmental performance. A cohort of 72 preschool children was studied (38 females, 34 males; mean age 3 years 8 months, SD 1 year 2 months, range 2 to 5 years) who were considered to be at high risk due to placental insufficiency. The cohort was divided into four categories of neurological status: (1) minimal cerebral palsy (MCP) with independent walking before age 2 years; (2) Amiel-Tison triad (ATT) including imbalance of passive axial tone, phasic stretch reflex in triceps surae, and cranial signs, particularly on the squamous suture; (3) intermediate with one or two of the three ATT signs; and (4) absence of neurological findings. Six subscales of the Griffiths Mental Developmental Scales assessing locomotion, eye-hand coordination, interpersonal skills, language, performance, and practical reasoning were administered. Significant differences were found according to neurological status in three specific domains of development: coordination (F=2.84, p=0.04), language (F=3.65, p=0.02), and practical reasoning (F=3.62, p=0.02). In addition, significant differences were also found in language (L) and practical reasoning (R) performances according to the side of the abnormal stretch reflex: bilateral stretches (L=87.8; R=75.3) or an isolated right stretch (L=95.3; R=83.6) are more strongly associated with impaired developmental performances than an isolated left stretch (L=101.3; R=88.2) with F=2.94; p=0.04 for language and F=3.00, p=0.04 for practical reasoning. We concluded that a short neurological examination, easily performed by pediatricians and family practitioners, can identify permanent markers of minor brain damage occurring before, during, or soon after birth and so anticipate consequences.

Canada↗
PubMed1992

Nonketotic hyperglycinemia presenting with pin-point pupils and hyperammonemia.

We describe two siblings who presented with lethargy, decreased sucking, respiratory failure and seizures in their first days of life. Pin-point pupils were noted in both siblings. Amino acid analysis revealed elevated concentrations of glycine in plasma and cerebrospinal fluid (CSF), with abnormal CSF/plasma ratios, compatible with hyperglycinemia. Urine organic acid analysis was unremarkable. Hyperammonemia was found in both siblings, but this subsided within 24-72 h. We suggest that pin-point pupils may be an additional presenting sign of nonketotic hyperglycinemia and, if looked for early enough, hyperammonemia may be found in this disorder.

Ammonia↗
PubMed1970

Electrophysiological studies in diabetic neuropathy.

In 30 patients with diabetic neuropathy sensory potentials in the median nerve, motor conduction in the lateral popliteal and median nerves, and electromyographic findings in distal and proximal muscles were compared with the severity of symptoms and signs. All patients had abnormalities in at least one of the electrophysiological parameters. The sensory potentials were the most sensitive indicator of subclinical involvement; abnormalities were found in 24 patients, 12 of whom had no sensory symptoms or signs and five of whom had no other clinical or electrophysiological evidence of neuropathy in the upper extremities. This indicates that sensory nerve fibres may be affected before motor. The next most sensitive parameter was the presence of fibrillation potentials, found in more than half the distal muscles examined. Slowing in motor conduction in the lateral popliteal nerve was the only electrophysiological change correlated to the severity of the neuropathy, and no other electrophysiological parameter was correlated to the duration or the severity of the neuropathy or the diabetes. An onset of neuropathy before or simultaneously with the manifestations of the diabetes, as well as the frequent occurrence of asymptomatic changes in sensory conduction, support the evidence at hand that the neuropathy develops concomitantly with and as an integral part of the metabolic disturbance rather than as a consequence of the vascular complications of diabetes. Of three patients with clinical signs or symptoms of a diabetic amyotrophy, two had asymptomatic electrophysiological abnormalities in distal nerves and muscles, consistent with widespread involvement of the peripheral nerves. The third patient had electromyographic changes in the medial vastus muscles suggestive of a myopathy. Motor and sensory conduction in distal and proximal nerves were normal.

Adult↗
PubMed2002

Anorectal involvement is frequent in limited systemic sclerosis.

The gastrointestinal tract, particularly the oesophagus, is affected in about half of all patients with systemic sclerosis. Only a few studies so far have dealt with the anorectal tract. We studied the anal function using anorectal manometry in 12 patients with limited systemic sclerosis. We also studied the oesophageal function. For the oesophagus, we measured the difference between intragastric and oesophageal pressure, while for the anorectal tract we investigated the maximum resting pressure, the maximum voluntary squeeze effort and the rectoanal inhibitory reflex. Maximum resting pressure and maximum voluntary squeeze effort were found to be decreased in all patients. The rectoanal inhibitory reflex was abnormal in four patients. Statistical analysis showed a significant correlation between maximum resting pressure and maximum voluntary squeeze effort. No correlation was found between oesophageal and anorectal involvement. Anorectal dysfunction is common in patients with limited systemic sclerosis. We suggest that these patients should have an evaluation of their anorectal function including anorectal manometry.

Anal Canal↗
PubMed1991

Acetazolamide in the treatment of abnormal oculovestibular response.

We treated seven patients with incapacitating vertigo elicited by walking down a grocery store aisle or driving a car. Results of neurologic, neuro-ophthalmic, and neuroradiologic examinations were normal. Episodic vertigo secondary to an abnormal oculovestibular response was diagnosed. Each patient was given a trial of 250 to 500 mg of acetazolamide daily. Symptoms resolved completely in four patients, two patients had near resolution of symptoms, and one patient had no relief. Carbonic anhydrase activity has been demonstrated in the inner ear, and acetazolamide has been shown to affect the ion balance of the inner ear fluids.

Acetazolamide↗
PubMed1995

Nitrous oxide depresses the H-reflex in children with cerebral palsy.

Hoffmann's reflex or H-reflex (HR) is an electrically elicited reflex that measures excitability of motoneurons and shares some physiologic properties with the deep tendon reflex. Children with tendon hyperreflexia due to cerebral palsy usually have higher amplitude HRs. Nitrous oxide (N2O) depresses the HR in patients with normal spinal reflexes, although the effect of N2O in conditions with hyperreflexia such as cerebral palsy is not known. We propose to determine the effect of N2O on the amplitude of the HR under general anesthesia in children with hyperreflexia due to cerebral palsy. We studied eight children undergoing selective dorsal rhizotomy (SDR) for the relief of spasticity. The maximum amplitudes of the HR (HRmax) and direct motor response (MRmax) were routinely evoked under the following anesthetic conditions: 1) sufentanil and 66% N2O/33% oxygen; and 2) sufentanil and 100% oxygen. The HRmax amplitude was significantly lower when N2O was part of the inspired gas mixture. The differences between the no N2O and the 66% N2O groups were significant. The MRmax did not change significantly. Abnormal spinal reflexes seen in spastic diplegia can be abolished by inhaled N2O. This finding also suggests that N2O-induced depression of spinal reflexes should be a consideration during physiologic monitoring of the spinal cord under general anesthesia.

Cerebral Palsy↗
PubMed2001

Does high-frequency pseudo-random rotational chair testing increase the diagnostic yield of the eng caloric test in detecting bilateral vestibular loss in the dizzy patient?

OBJECTIVES: To assess the incremental diagnostic yield of testing vestibulo-ocular (VOR) gain with high-frequency pseudo-random rotational chair (PsRRC) over testing with bithermal electronystagmography caloric tests in the dizzy patient, particularly in detecting bilateral vestibular loss. PATIENTS AND METHODS: One hundred ninety-eight patients presenting with dizziness underwent PsRRC and caloric testing. The VOR gain on PsRRC was measured at 0.32 to 5.0 Hz, with gain categorized as normal or decreased. PsRRC results were compared with caloric responses, also categorized as normal, or into graded categories of unilateral or bilateral vestibular loss. RESULTS: Reduced PsRRC gain was found in 29 (15%) patients, and reduced caloric tests responses in 70 (35%), with 25 (13%) having bilateral loss. Of patients with reduced chair gain, 25 of 29 (86%) demonstrated bilateral caloric loss. PsRRC gain was normal in most patients with unilateral caloric weakness, but was decreased in all patients with bilateral caloric weakness. The probability of a patient with completely normal caloric responses having an abnormal rotation chair in this study group was under 1% (1 of 128). CONCLUSIONS: PsRRC testing does not offer much additional diagnostic benefit when caloric responses are normal. It is useful in specific conditions, such as unilateral caloric loss for which the patient is not compensating, borderline caloric loss when traditional water caloric tests cannot be used, or for monitoring progressive bilateral vestibular loss.

Adult↗
PubMed2000

Rhesus monkeys with late-onset hydrocephalus differ from non-impaired animals during neonatal neurobehavioral assessments: six-year retrospective analysis.

BACKGROUND AND PURPOSE: A recent case study indicated that a hydrocephalic rhesus monkey had abnormal response patterns in a standardized neonatal primate assessment. We conducted a retrospective study to determine whether this assessment could also differentiate neonatal rhesus monkeys that appeared normal but developed signs of hydrocephalus later in life from neonates with normal development and no evidence of hydrocephalus. METHODS: One-hundred eighty-two rhesus monkeys were assessed on postnatal days 7, 14, 21, and 30. As neonates, clinical signs of hydrocephalus or other illnesses were not evident in any animal. Six monkeys developed signs of hydrocephalus between 5 months and 5 years of age, and each received confirmed diagnoses of hydrocephalus at necropsy. RESULTS: Compared with colony norms, the monkeys that developed hydrocephalus had diminished orientation abilities, more muscle tension, less behavioral evidence of distress, and more pronounced responses to some reflex-evoking stimuli, and difficulty in self-righting (day 7 only). Discriminant function analysis comparing the hydrocephalic animals with a matched control group provided a high probability of correct group assignment at days 7, 14, and 21. CONCLUSIONS: Some as yet undetermined factor may predispose some monkeys to develop hydrocephalus, which may also be reflected in different scores on neurodevelopmental test items during early infancy.

Acoustic Stimulation↗
PubMed1998

Spectroscopic imaging of frontal neuronal dysfunction in hyperekplexia.

We used proton magnetic resonance spectroscopic imaging (MRSI) to assess in vivo cortical neuronal involvement in hyperekplexia. Cerebral neuronal function was measured using proton MRSI in four unrelated patients with hyperekplexia and 20 healthy controls. All patients had the major form of hyperekplexia, with additional atypical clinical features in two of them. Family history was positive in three patients and absent in one. The neuronal marker N-acetylaspartate (NAA), choline-containing compounds (Cho) and creatine (Cr) were measured in frontal, central and parietal areas. The MRSI showed a reduction of the relative resonance intensity of NAA/(Cr + Cho) in frontal and central regions in three patients, and in the right frontal region of the fourth. In one patient a second MRSI showed normal relative NAA resonance intensities over both temporal lobes as well as in the brainstem. In two subjects the topography of EEG abnormalities in the frontal lobes coincided with the MRSI findings. This proton MRSI study indicates the presence of frontal neuronal dysfunction in hyperekplexia. Whether this represents cortical dysfunction or an epiphenomenon of diencephalic or brainstem abnormalities remains open. However, the observation of normal proton MRSI in the temporal regions and brainstem in one of the patients seems to concur with the hypothesis of a facilitatory role of cortical dysfunction within areas of sensorimotor representation in the generation of the pathological startle reaction in hyperekplexia.

Adolescent↗
PubMed1979

Cholinergic dysautonomia and Eaton-Lambert syndrome.

Cholinergic autonomic function was abnormal in a 47-year-old woman with Eaton-Lambert syndrome (ELS), not associated with carcinoma. Pupillary constriction to light and accommodation, sweating, lacrimation, and salivation were all affected. There was no evidence of Sjogren syndrome or botulinum intoxication. The defect of acetylcholine release from presynaptic terminals in the Eaton-Lambert syndrome may not be restricted to the neuromuscular junction of skeletal muscle.

Cholinergic Fibers↗