The differential diagnosis of erythema nodosum.

Erythema nodosum is an uncommonly seen skin eruption which may be a marker of underlying systemic or infectious disease. It may also occur as a reaction to a variety of medications. The diagnosis of erythema nodosum should prompt a thorough investigation of possible causes or associated conditions which may be treatable. This paper presents a case of erythema nodosum and reviews the differential diagnosis of its causes and of similar appearing skin lesions.

Response of the Lambert-Eaton myasthenic syndrome to treatment of associated small-cell lung carcinoma.

We evaluated the outcome in 16 patients with Lambert-Eaton myasthenic syndrome (LEMS) associated with histologically verified small-cell carcinoma (SCC). Thirteen patients received specific tumor therapy (chemotherapy, radiation therapy, or resection) and most also received pharmacologic and immunologic treatment for LEMS. Seven of 11 patients surviving for more than 2 months after tumor therapy showed substantial neurologic improvement (1 patient being in complete remission at 7 years); in 3 of 11 improvement was transient. An EMG index of disease severity (compound muscle action potential amplitude in abductor digiti minimi) was significantly increased at final follow-up (p less than 0.01; n = 11). A pretreatment amplitude greater than 3.0 mV was a good prognostic sign. We conclude that a combined treatment approach in SCC-LEMS usually results in neurologic improvement.

Antibody-mediated pure neutrophil aplasia, recurrent myasthenia gravis and previous thymoma: case report and literature review.

We describe a case of neutrophil aplasia in a woman with recurrent myasthenia gravis and a past history of thymoma. Bone marrow showed virtually absent granulopoiesis but normal erythropoiesis and megakaryopoiesis. Bone marrow cultures showed no growth of granulocyte/mononuclear cell progenitors (CFU-GM). She was treated with immunosuppression including azathioprine, and her neutrophil count returned to normal. Serum before treatment, and also an IgG fraction thereof, inhibited CFU-GM growth both in autologous 'remission' marrow and in allogeneic marrow. She remains in complete remission 36 months after starting azathioprine. This association is extremely rare, and was formerly associated with a grim prognosis.

The Lambert-Eaton myasthenic syndrome. A review of 50 cases.

The clinical and electrophysiological features of 50 consecutive patients with the Lambert-Eaton myasthenic syndrome (LEMS) have been analysed. Carcinoma was detected (CD group) in 25, of whom 21 had small cell lung cancer (SCLC). SCLC was evident within 2 yrs of onset of LEMS symptoms in 20/21 cases, and at 3.8 yrs in 1/21. In the cases in whom no carcinoma was detected (NCD group), 14/25 had a history of LEMS greater than 5 yrs. The dominant neurological features were similar in the CD and NCD groups, and consisted of proximal lower limb weakness (100%), depressed tendon reflexes (92%) with posttetanic potentiation (78%), autonomic features, especially dryness of the mouth (74%) and mild/moderate ptosis (54%). The compound evoked muscle action potential amplitude in abductor digiti minimi was below the lower limit of control values in 48/50, and the increment following maximum voluntary contraction above the upper limit of control values in 48/50. Single fibre electromyographic abnormalities were found in 29/29 cases. The analysis indicates that a patient presenting with LEMS has a 62% risk of an underlying SCLC, and that this risk declines sharply after 2 yrs, becoming very low at 4 to 5 yrs. It is argued that in SCLC cases antigenic determinants on tumour cells initiate the autoimmune response, often early in the course of the malignancy, but that the association of LEMS with tumours other than SCLC may be fortuitous. In the latter, and in NCD patients, the initiating factor(s) are unknown.

McArdle's sign in multiple sclerosis.

A patient with multiple sclerosis is reported in whom neck flexion produced a reversible deterioration in gait and an increase in the degree of pyramidal weakness of the lower limbs. The name McArdle's sign is proposed.

Meningitis due to Branhamella catarrhalis.

We report a case of Branhamella catarrhalis meningitis which was unusual in that the patient was a healthy immunocompetent adult, the onset was subacute, and the cerebrospinal fluid pleocytosis was predominantly lymphocytic. Following treatment with intravenous penicillin, recovery was complete apart from residual cortical dysarthria.

Regeneration following tibial nerve crush in the rabbit: the effect of proximal constriction.

In order to test the regenerative capacity of atrophic axons, a constricting ligature was placed around the proximal tibial nerve of the rabbit, and the nerve crushed at the ankle one week later. Axonal atrophy with altered g ratios was subsequently confirmed in fibres distal to the site of ligature and proximal to the site of crush. In nerves with tight proximal ligatures the reinnervation of plantar muscles and the subsequent recovery of distal motor latency were delayed, indicating impaired regeneration. This result may be relevant to the "double-crush" theory of nerve damage.

Adaptation of the myelin sheath during axonal atrophy.

Distal axonal atrophy was produced by proximal constriction of the tibial nerve in the rabbit. Single fibres were teased from the distal tibial nerve, and a selected internode from each fibre was measured and then cut transversely for electron microscopy, so that axon area and perimeter, myelin lamellar number and periodicity, and myelin spiral length could be related to the length of the internode which had been sectioned. When sections from atrophic and control internodes of similar length were compared, there was no difference in the mean number of myelin lamellae or their periodicity in the two groups, in spite of a mean reduction in axon cross-sectional area of 60% in the atrophic group. Mean values for axon perimeter and myelin spiral length were reduced by 14%-15% in atrophic fibres, compared with controls. The reduction in mean myelin spiral length might seem to imply that myelin had been lost from the atrophic internodes. However, there was also an increase in the length of individual lamellae in the long axis of the internode, due to the irregular folding of the sheath, and it is uncertain whether any overall change in internodal myelin volume had occurred.

Changes in the compact myelin of single internodes during axonal atrophy.

Distal axonal atrophy was produced by proximal constriction of the tibial nerve in the rabbit. Transverse sections were studied by light and electron microscopy at 10 micron intervals along individual internodes of both atrophic and normal tibial nerve fibres. During axonal atrophy there were marked changes in axonal configuration at different levels within the territory of a single Schwann cell. These resulted in changes in the lengths of the axon perimeter and myelin spiral, without causing any alteration in the numbers of myelin lamellae or their spacing. Comparable changes in axon perimeter and myelin spiral length were seen in transverse sections through the paranodal and nuclear regions of normal fibres. These results show that local variations in axonal calibre or shape are associated with appropriate adjustments to the length of the myelin spiral, without a change in the number of lamellae, and thus of sheath thickness.