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Biomedical subjects

R G Auger

Publications and source records attributed to R G Auger.

10 recordsLinked to original sources
PubMed1992

Hemimasticatory spasm: clinical and electrophysiologic observations.

Hemimasticatory spasm is a rare disorder of the trigeminal nerve that produces involuntary jaw closure due to paroxysmal unilateral contraction of jaw-closing muscles. We report three patients with this disorder. Electrophysiologic studies demonstrated normal blink and masseter reflexes. The masseter inhibitory reflex was absent during periods of spasm. Needle electromyography demonstrated irregular bursts of motor unit potentials that were identical to the pattern observed in hemifacial spasm. The electrophysiologic findings suggest ectopic excitation of the trigeminal motor root or its nucleus, an abnormality that is analogous to ectopic excitation of the facial nerve in hemifacial spasm. One patient improved temporarily with surgery, one improved while on treatment with carbamazepine, and another responded favorably to botulinum toxin injection.

Adult↗
PubMed1992

Preservation of the masseter reflex in Friedreich's ataxia.

In Friedreich's ataxia, the muscle stretch reflexes are absent or hypoactive in the upper and lower extremities because of pathologic involvement of the dorsal root ganglion cells. Paradoxically, the masseter reflex remains unaffected and may even be hyperactive in some cases. The masseter reflex is hypothesized as unique among stretch reflexes in that its afferent nerve cell body (the mesencephalic nucleus) is located intra-axially within the brainstem rather than in the craniospinal ganglia, where the afferent nerve cell bodies subserving the other stretch reflexes are located. This study supported this hypothesis by demonstrating that the masseter reflex is (1) usually absent in patients who are areflexic as a result of primary disorders of peripheral nerve axons or myelin, and (2) preserved in other disorders that primarily involve the dorsal root ganglion cells.

Blinking↗
PubMed1992

Management of unruptured intracranial arteriovenous malformations: a decision analysis.

The management of unruptured intracranial arteriovenous malformations (AVMs) is controversial. Some authorities favor elective excision of the AVM before it bleeds, whereas others advise nonintervention unless the AVM bleeds, at which time surgical excision is performed in those who survive. A Markov model was developed that stimulates a clinical trial in which cohorts of patients with unruptured AVMs were assigned to either elective excision of their AVMs or conservative treatment (unless the AVM bled). Incremental utilities for both strategies were calculated at the end of each year after the beginning of the trial and are expressed as quality and risk-adjusted life years. The process was continued until all members of the cohorts had died. The mean quality and risk-adjusted life expectancy for members of a cohort was calculated by dividing the total number of quality and risk-adjusted life years the cohort had accumulated by the size of the cohort. If the baseline values for surgical complications were used in the computation, the quality and risk-adjusted life expectancy for the surgical cohorts was at least 1 quality and risk-adjusted life year greater than for nonsurgical cohorts up to age 44. If a more favorable complication rate were used, elective surgery could benefit selected patients in their early 60s when the location and configuration of the AVM was favorable. Elective surgical resection is justified in many instances before rupture, particularly in young patients who have intracranial AVMs that have a favorable location, size, and venous drainage.

Cerebral Hemorrhage↗
PubMed1990

Hemifacial spasm in Rochester and Olmsted County, Minnesota, 1960 to 1984.

The incidence of hemifacial spasm in residents of Olmsted County, Minnesota, was studied by reviewing the medical records of patients residing in the community between 1960 and 1984. The average annual incidence rate was 0.74 per 100,000 in men and 0.81 per 100,000 in women, age-adjusted to the 1970 US white population. The average prevalence rate was 7.4 per 100,000 population in men and 14.5 per 100,000 in women. The incidence and prevalence rates were highest in those from 40 to 79 years of age.

Adult↗
PubMed1990

Trigeminal sensory neuropathy associated with decreased oral sensation and impairment of the masseter inhibitory reflex.

We describe 4 patients with severe trigeminal sensory neuropathy whose main disability resulted from impaired intraoral sensation associated with disturbances of mastication and swallowing. Each patient had an abnormal blink reflex and jaw jerk. In addition, the masseter inhibitory reflex was absent in 3 patients and abnormal in the 4th. This reflex plays a role in the reflex control of mastication and can easily be elicited in normal subjects by stimulation of the skin and mucous membrane in the distribution of the 2nd and 3rd divisions of the trigeminal nerve while the jaw-closing muscles are contracting. Disturbed intraoral sensation combined with impaired trigeminal reflexes (particularly the masseter inhibitory reflex) interferes with neural mechanisms that regulate chewing and can be a source of severe disability in patients with trigeminal sensory neuropathy.

Aged↗
PubMed1989

Hemifacial spasm associated with epidermoid tumors of the cerebellopontine angle.

Hemifacial spasm (HFS) is rarely due to serious compressive lesions, such as tumors, aneurysms, or vascular malformations, located in the cerebellopontine angle. Because of the interesting association of HFS with epidermoid tumors, we reviewed the records of all patients with HFS and all patients with intracranial epidermoid tumors seen from January 1975 to December 1986. Of the 18 patients who had epidermoid tumors of the cerebellopontine angle, 3 (17%) had a facial movement disorder that resembled HFS at sometime during their illness. There were 429 patients who had HFS with no obvious serious compressive lesion of the facial nerve. Therefore, HFS was associated with epidermoid tumor in 0.7% of cases. All 3 patients developed other findings due to involvement of adjacent neural structures. Patients with HFS have a low probability of having a serious compressive lesion, but those with atypical features should be evaluated for cerebellopontine angle masses such as epidermoid tumors.

Brain Neoplasms↗
PubMed1988

Facial paralysis and occult parotid cancer. A characteristic syndrome.

Extratemporal involvement of the seventh cranial nerve is often secondary to a tumor of the parotid gland. We describe six patients who had facial paralysis associated with an occult malignant neoplasm of the parotid gland. Initial evaluations in these patients, including computed tomography and magnetic resonance imaging, provided no evidence of a parotid tumor. Four of the six patients had a progressive triad of ear pain, facial paralysis, and sensory loss in the second and third divisions of the trigeminal nerve. This pattern indicates a high probability of a malignant lesion of the parotid gland, even in the presence of normal findings on noninvasive studies.

Adenocarcinoma↗
PubMed1979

Hemifacial spasm: clinical and electrophysiologic observations.

Twenty-three patients with hemifacial spasm were studied clinically and electrodiagnostically. Seven patients had mild facial weakness. All patients had clinical evidence of synkinesis, which often varied considerably. Facial nerve conduction and blink reflex latencies were normal. Facial synkinesis could be measured objectively on the involved side in all patients by simultaneously recording from the orbicularis oculi and orbicularis oris muscles at the time of supraorbital nerve stimulation. Using this procedure, synkinesis was also observed in association with aberrant regeneration after Bell palsy but was not seen in other movement disorders involving the face. The demonstration of synkinesis and its variability in hemifacial spasm can be of value in differentiating hemifacial spasm from other movement disorders affecting the face and provides further insight into its pathogenesis.

Electric Stimulation↗