Biomedical subjects

G Midroni

Publications and source records attributed to G Midroni.

5 recordsLinked to original sources

PubMed1996

Chronic inflammatory demyelinating polyradiculoneuropathy: unusual clinical features and therapeutic responses.

We present three patients with atypical chronic inflammatory demyelinating polyradiculoneuropathy and discuss the management of patients who appear treatment resistant or present with unusual manifestations. The clinical features of the patients included massive nerve root hypertrophy causing myelopathy and movement-provoked paresthesia, pupillary dysfunction, visual loss due to increased intracranial pressure, and focal brachial plexus involvement. Each patient ultimately required prolonged courses of immune modulating therapy before benefit was attained, illustrating the importance of intensive and prolonged treatment combined with objective assessment of response to therapy.

Adult↗

PubMed1992

Rapid postanoxic calcification of the basal ganglia.

A 22-year-old male diabetic on hemodialysis suffered a cerebral anoxic event. Serial CT showed the development of basal ganglia calcification over a period of no more than 17 days. It appears that the basal ganglia may develop petechial hemorrhage, necrosis, calcification, or combinations of these following an anoxic insult. The neuropathologic substrate and mechanism of rapid postanoxic calcification are unknown.

Adult↗

PubMed1991

Adult peripheral neuroepithelioma in Meckel's cave.

A case of peripheral neuroepithelioma arising from the trigeminal nerve in Meckel's cave is presented. The discussion emphasizes the pathological criteria for the diagnosis of a peripheral neuroepithelioma and the current controversy about the classification of this and related tumors.

Humans↗

PubMed1989

Excitability of corticospinal neurons during tonic muscle contractions in man.

A magnetic stimulus applied to the human scalp over the motor cortex causes a short latency contraction of contralateral limb muscles. This is presumed to result from the indirect excitation of corticospinal neurons with monosynaptic connections to motoneurons. The excitability of these cortical neurons can be estimated from the magnitude of the postsynaptic potentials produced in spinal motoneurons by a given magnetic stimulus. In man the characteristics of these postsynaptic potentials can be derived from changes in the firing probability of single motor units. When a subject increases the level of a sustained voluntary contraction the excitability of the corticospinal neurons estimated in this way becomes less. We conclude that the additional synaptic input to motoneurons required to maintain a stronger muscle contraction comes from fiber systems other than the population of fast corticospinal neurons activated by magnetic stimulation.

Action Potentials↗

PubMed1989

How synaptic noise may affect cross-correlations.

The relationship between a postsynaptic potential (the 'test PSP') and the profile of the cross-correlation that it produces in a repetitively discharging mammalian motoneuron, with and without synaptic noise, has been explored by computer stimulation. In a noiseless motoneuron the cross-correlation profile represents the first derivative of PSP shape except where 'shadowing' occurs (Eqn. 1a-c). When synaptic noise is present the relationship changes. When the amplitude of spike-like 'noise PSPs' occurring at regular intervals reaches a critical value (Eqn. 2), all threshold crossings involve noise PSPs. Under these circumstances termed 'just maximally effective synaptic noise', the cross-correlation represents test PSP directly (Eqn. 3a). When the interval between noise PSPs is shortened the relationship reverts to the first differential (Eqn. 4a-c). If the amplitude of the noise PSPs is less than the critical value (Eqn. 5) the cross-correlation profile is represented in a complex way by a combination of the first derivative of the upper part and the direct representation of the lower part of the test PSP. The area of the cross-correlation peak above baseline provides the most reliable estimate of EPSP amplitude in a noiseless motoneuron (Eqn. 6a). This area may fall to half for the same triangular test EPSP in the presence of just maximally effective synaptic noise (Eqn. 7a). In general, the presence of synaptic noise leads to underestimation of EPSP amplitude. These general principles remain valid for physiological noise consisting of randomly occurring EPSPs and allow certain experimental findings in cat motoneurons to be understood.

Animals↗