[Syringomyelia in orthopedic practice]

Three females with syringomyelia and atrophic shoulder arthropathy, in one patient associated also with hypertrophic elbow arthropathy and Morvan syndrome have been presented. Despite long duration and apparent symptoms the condition has been diagnosed only during hospitalization.

Intermittent diplopia and strabismus caused by ocular neuromyotonia

PURPOSE

Two cases illustrate the symptoms, signs, etiologies, and treatment of ocular neuromyotonia (ONM).

METHODS

The histories, neuroradiologic tests, and/or biopsy revealed the etiologies of ONM in both patients. Clinical observations, videotaping, and electronic eye movement recordings documented the eye movements.

RESULTS

A 72-year-old man with chronic arachnoiditis following myelography with thorium dioxide (Thorotrast) developed intermittent diplopia and a partial right third nerve palsy. Left gaze induced spasm of the right medial rectus. Right gaze produced right lateral rectus spasm. A 66-year-old woman, who had radiation treatment for a pituitary tumor and acromegaly, had intermittent spasm of the left medial rectus muscle and left esotropia. The episodes occurred spontaneously and were induced by right gaze. A left internuclear ophthalmoplegia was also found. Carbamazepine (Tegretol) abolished the ONM in both patients.

CONCLUSIONS

Although ONM is an unusual cause of intermittent diplopia and strabismus, its distinctive clinical features identify it. Injury to the peripheral cranial nerves probably leads to segmental demyelination, axonal hyperexcitability, and a self-perpetuating, reverberating circuit, which causes spasms of the extraocular muscles.

Myotonia in a cocker spaniel

A 16-week-old, male cocker spaniel suffering from pelvic-limb "bunny hopping" as well as rigidity, spasticity, and ataxia in all limbs was evaluated. The clinical features, electrophysiological abnormalities, and muscle histopathological and histochemical evaluations led to a diagnosis of congenital myotonia. Myotonia is a disorder of skeletal muscle characterized by delayed relaxation of the muscle fiber in response to voluntary, mechanical, or electrical stimulation. The pathophysiology of congenital myotonia remains controversial; currently proposed pathomechanisms are discussed. To the authors' knowledge, this is the first case of congenital myotonia reported in a cocker spaniel.

Peripheral ocular motor disorders

In the reviewed period, articles on peripheral eye movement disorders covered interesting aspects. Localizing value of associated signs, repetitive presentations of palsies, and classical quotations are stressed for the oculomotor nerve. The superior oblique is correlated to central nervous system disorders when overacting in pediatric patients or when ocular torsion is matched to the perceived vertical tilt. The family "pseudo" brought two of its members: "pseudo" myasthenia and "pseudo" myotonia. Mitochondrial citopathies with ocular manifestations can overlap among the different clinical types, eg, Kearns-Sayre, MELAS (mitochondrial encephalopathy-lactic acidosis and strokelike episodes), MERFF (myoclonic epilepsy and ragged red fibers). The diagnostic value of DNA mutations is emphasized in those syndromes. Imaging of the carotid arteries provides useful hints in cases where the lumen is narrowed due to internal processes or external compression; its interpretation is not only of diagnostic but of prognostic value. Certain otorhinolaryngology surgical procedures can damage the orbital muscles and produce serious inconvenience to the ocular motility. Analyzing the involved structures the therapeutic gesture can be determined. Diplopia after cataract surgery or retinal detachment repair is due to different factors, anesthetics, or implant location and is implied in every case.

The Schwartz-Jampel syndrome

Three sibs with severe manifestation of Schwartz-Jampel syndrome are described. All died due to respiratory complications. Early diagnosis might help to prevent this complication. In addition to electromyography, skeletal radiographs can be helpful in establishing the diagnosis. The radiological manifestations of this syndrome are reviewed.

["Abducens neuromyotonia" with partial oculomotor paralysis]

Paroxysmal involuntary spasms of extraocular eye muscles which can lead to reversible pathological eye positions and limitations of eye movements are etiologically heterogenous. Despite the diagnostic difficulty, they are important as a neurological sign because of the usually good response to treatment. We report on a patient with the unusual combination of ocular neuromyotonia with brief paroxysmal tonic lateral deviation of the left eye and a concomitant partial third nerve palsy. The paroxysmal episodes disappeared with carbamazepine therapy. Possible pathomechanisms are discussed.

Neuromyotonia: report of a case

Neuromyotonia is a rare condition of peripheral nerve dysfunction characterized by the signs of motor nerve hyperactivity, namely, myokymia, fasciculations, and muscular stiffness. Relaxation of voluntary muscle contraction is delayed, and fluid movements are impaired to a variable degree. Signs of sensory involvement are less frequent. Usually, therapy with carbamazepine or phenytoin provides rapid improvement. In the present communication, a typical case is reported, and the most important differential diagnoses are outlined.

Mistaken diagnoses in continuous muscle fiber activity of peripheral nerve origin

The syndrome of continuous muscle fiber activity of peripheral nerve origin has manifestations that resemble those of many other more common neurologic disorders during childhood and infancy. This similarity often leads to misdiagnosis when an adequate index of suspicion is not entertained and a comprehensive electromyographic examination is not performed. Two affected patients from 1 family are reported to illustrate the type of diagnostic errors that were made before the establishment of the correct diagnosis.

Serum parvalbumin, an indicator of muscle disease in murine dystrophy and myotonia

The soluble Ca(++)-binding protein parvalbumin (PV) is highly concentrated in fast muscle fibers of the wild type mouse. Employing Sandwich ELISA, we have shown that PV is present in the serum of normal mice and that its level is indicative of the disease status of muscle. Elevated PV levels were found in mice with X-linked dystrophy (mdx) and reduced levels in myotonic (ADR) mice. Serum creatine kinase (CK) levels were elevated in mdx and normal in ADR mice. Because myotonic mouse muscle has a strongly reduced PV content, the reduced PV serum level in ADR mice indicated that serum PV is derived from skeletal muscle. Serum PV in mdx mice, in which muscle PV content is close to normal, is a measure of the necrosis of fast muscle fibers. Serum levels of PV and CK were not significantly elevated in heterozygous (mdx/+) carrier females. Serum PV in Duchenne patients was below the limit of detection.

Schwartz-Jampel syndrome: I. Clinical, electromyographic, and histologic studies

In a new, typical case of Schwartz-Jampel syndrome (SJS) the origin of the disorder was found to be purely myogenic. Concentric needle EMG showed abundant and persistent spontaneous activity, maximal at insertion, and uninfluenced by local curarization. Single-fiber EMG showed rather stable, sometimes intermittent, discharge series with occasional amplitude and/or frequency fluctuations. It could be demonstrated that this activity did not consist of complex repetitive discharges, but of independent activity of individual muscle fibers. This contrasts with findings by other investigators that have been published in this journal. Light microscopic studies of quadriceps and intercostal muscles showed no abnormalities, whereas electron-microscopic findings were in accordance with earlier studies in SJS. Endplate analysis revealed no specific changes; the postsynaptic structures gave the impression of an accelerated-maturation.

AAEE minimonograph #27: differential diagnosis of myotonic syndromes

Recent advances in neuromuscular diseases have also widened the diagnostic spectrum of myotonic disorders. Treatment, prognosis, and genetic aspects are different in the various syndromes and mandate a correct diagnosis. The combination of neurologic examination, standard EMG, exercise test, cold exposure, potassium loading, eye examination, and pedigree analysis allows correct classification of nearly all patients with myotonic disorders. In this review emphasis is placed on clinical features and electrophysiologic evaluation.

[Neuromyotonic syndrome]

A syndrome with constant rest activity was observed in the EMG of a 28-years-old female patient. An H-reflex was detected for normal nerve conduction velocity. Hypomagnesemia was striking among the laboratory values. Bioptic investigation yielded centralisation of nuclei, variations in the diameter of muscle fibres and a predominance of type I fibres. The findings and the response to Finlepsin point to neuromyotonic syndrome.