title: Clinical Features of Neuromuscular Disorders in Patients with N-Type Voltage-Gated Calcium Channel Antibodies.
abstract: Neuromuscular junction disorders affect the pre- or postsynaptic nerve to muscle transmission due to autoimmune antibodies. Members of the group like myasthenia gravis and Lambert-Eaton syndrome have pathophysiologically distinct characteristics. However, in practice, distinction may be difficult. We present a series of three patients with a myasthenic syndrome, dropped-head syndrome, bulbar and respiratory muscle weakness and positive testing for anti-N-type voltage-gated calcium channel antibodies. In two cases anti-acetylcholin receptor antibodies were elevated, anti-P/Q-type voltage-gated calcium channel antibodies were negative. All patients initially responded to pyridostigmine with a non-response in the course of the disease. While one patient recovered well after treatment with intravenous immunoglobulins, 3,4-diaminopyridine, steroids and later on immunosuppression with mycophenolate mofetil, a second died after restriction of treatment due to unfavorable cancer diagnosis, the third patient declined treatment. Although new antibodies causing neuromuscular disorders were discovered, clinical distinction has not yet been made. Our patients showed features of pre- and postsynaptic myasthenic syndrome as well as severe dropped-head syndrome and bulbar and axial muscle weakness, but only anti-N-type voltage-gated calcium channel antibodies were positive. When administered, one patient benefited from 3,4-diaminopyridine. We suggest that this overlap-syndrome should be considered especially in patients with assumed seronegative myasthenia gravis and lack of improvement under standard therapy.
authors.affiliation: Department of Neurology, University Duisburg-Essen , Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Totzeck
authors.affiliation: Department of Neurology, University Duisburg-Essen , Germany.
authors.forename: Petra
authors.initials: P
authors.lastname: Mummel
authors.affiliation: Department of Neurology, University Duisburg-Essen , Germany.
authors.forename: Oliver
authors.initials: O
authors.lastname: Kastrup
authors.affiliation: Department of Neurology, University Duisburg-Essen , Germany.
authors.forename: Tim
authors.initials: T
authors.lastname: Hagenacker
keywords: 3,4-diaminopyridin; dropped-head syndrome; myasthenia gravis; neuromuscular junction disorders; voltage gated calcium channels