In most of these cases, LEMS is the first symptom of the lung cancer, and it is otherwise asymptomatic.LEMS may also be associated with endocrine diseases, such as hypothyroidism (an underactive thyroid gland) or diabetes mellitus type 1. Myasthenia gravis, too, may happen in the presence of tumors (thymoma, a tumor of the thymus in the chest); people with MG without a tumor and people with LEMS without a tumor have similar genetic variations that seem to predispose them to these diseases. HLA-DR3-B8 (an HLA subtype), in particular, seems to predispose to LEMS. Mechanism
In normal neuromuscular function, a nerve impulse is carried down the axon (the long projection of a nerve cell) from the spinal cord. At the nerve ending in the neuromuscular junction, where the impulse is transferred to the muscle cell, the nerve impulse leads to the opening of voltage-gated calcium channels (VGCC), the influx of calcium ions into the nerve terminal, and the calcium-dependent triggering of synaptic vesicle fusion with plasma membrane. These synaptic vesicles contain acetylcholine, which is released into the synaptic cleft and stimulates the acetylcholine receptors on the muscle. The muscle then contracts.In LEMS, antibodies against VGCC, particularly the P/Q-type VGCC, decrease the amount of calcium that can enter the nerve ending, hence less acetylcholine can be released from the neuromuscular junction. Apart from skeletal muscle, the autonomic nervous system also requires acetylcholine neurotransmission; this explains the occurrence of autonomic symptoms in LEMS. P/Q voltage-gated calcium channels are also found in the cerebellum, explaining why some experience problems with coordination.
According to clinical trials, topical fluoride treatment in the form of gel or varnish is effective in preventing tooth decay in children with enamel defects. Treatment with other topical agents, such as calcium phosphate (CPP-ACP), may also be effective in the remineralization of areas with congenital or carious enamel defects.In decayed teeth with enamel defects, only bonded restorations (e.g. glass ionomer, polyacid-modified composite resin and not amalgam) should be placed and cavity margins should not be placed in areas of defective enamel as this may lead to marginal leakage and recurrent decay. Stainless steel crowns with conservative preparation may be an effective method to eliminate sensitivity and prevent further breakdown in teeth with enamel defects requiring full-coverage crowns. Other conditions affecting enamel development
Hypomineralization or hypocalcification, as opposed to hypoplasia, refers to a decrease in the mineral content of the enamel, not the total amount present. It can vary in its presentation, and teeth may appear visually normal or highly translucent. Affected enamel is softer and more susceptible to acid, wear and decay. Molar-incisor hypomineralization
Molar-incisor hypomineralization (MIH) is a condition in which there are areas of hypomineralized or hypomatured enamel on the crowns of permanent molars and incisors. In these cases, teeth may lose their weakened enamel shortly after eruption and are highly susceptible to dental caries. Affected teeth are highly sensitive to chemical and thermal irritants, and may also be difficult to obtain anesthesia.