Autoantibodies Blocking M3 Muscarinic Receptors Cause Postganglionic Cholinergic Dysautonomia.

A 10-year-old girl presented with ileus, urinary retention, dry mouth, lack of tears, fixed dilated pupils, and diffuse anhidrosis 7 days after a febrile illness. We hypothesized that her syndrome was due to autoimmunity against muscarinic acetylcholine receptors, blocking their activation. Using an indirect enzyme-linked immunosorbent assay for all 5 muscarinic receptors (M1 -M5 ), we identified in the patient's serum antibodies that selectively bound to M3 receptors. In vitro functional studies confirmed that these autoantibodies selectively blocked M3 receptor activation. Thus, autoantibodies against M3 acetylcholine receptors cause acute postganglionic cholinergic dysautonomia. ANN NEUROL 2020;88:1237-1243.

Case of primary Sjogren's syndrome preceded by dystonia.

There are only six cases in literature that describe development of dystonia with Sjogren's syndrome (SS). We describe a case of a 43-year-old woman who presented with symptoms including movement disorder, sensory neurogenic bladder, sensory loss and neuropathic pain, migraine like headaches, musculoskeletal pain, Raynaud's phenomenon and dysautonomia. Symptoms started in 2000, with weakness that progressed to dystonia in 2003. Diagnostic work-up was inconclusive with negative inflammatory serologies, cerebrospinal fluid and MRI for many years. After patient developed sicca syndrome with dry eyes and mouth in 2009, her rheumatoid factor titre was elevated (550 IU/mL), erythrocyte sedimentation rate, anti-Sjogrens syndrome-related antigen A (anti-Ro/SSA) and anti-SSB/La: anti-Sjogrens syndrome-related antigen B (anti-La/SSB) became positive. Lip biopsy confirmed diagnosis of SS. She was diagnosed with primary SS with neurological involvement. Her symptoms responded well to intravenous methylprednisolone. Symptoms stabilised with trials of immune-suppressive therapy. This is a case that demonstrates the delay of diagnosing SS with preceding unique neurological association.

Antibody titers predict clinical features of autoimmune autonomic ganglionopathy.

Autoimmune autonomic ganglionopathy is a disorder of isolated autonomic failure associated with antibodies to the nicotinic acetylcholine receptor of the autonomic ganglia resulting in severe orthostatic intolerance, syncope, constipation, gastroparesis, urinary retention, dry mouth, dry eyes, blurred vision and anhidrosis. We report the autonomic test results, antibody titers and clinical findings in 8 patients with antibodies to the nicotinic acetylcholine receptor of the autonomic ganglia. There was a sigmoidal relation between the antibody titers and the fall in systolic blood pressure (r(2)=0.84). The threshold occurred with antibody titers of approximately 1 nmol/l. Over the linear portion of the sigmoid curve, with antibody titers in the 1-3 nmol/l range, increasing antibody titers resulted in more severe orthostatic hypotension (r=0.94, P<0.001). The saturation point of the sigmoidal relation occurred at approximately 3 nmol/l with drops in systolic blood pressure of approximately 100 mmHg during upright tilt. The antibody titers correlated inversely with the Valsalva ratio (r=-0.87, P<0.001), the 30:15 ratio (r=-0.84, P<0.001) and the expiratory to inspiratory ratio (r=-0.67, P<0.01). Patients with orthostatic intolerance, anhidrosis, constipation, urinary dysfunction, sicca syndrome and pupillary dysfunction had higher antibody titers than subjects that did not (P<0.01 in all cases). Autoimmune autonomic ganglionopathy is a clinically heterogeneous disease with variable presentation, particularly in subjects with lower antibody titers. Our data suggest that patients with higher antibody titers have wide spread dysautonomia while those with lower antibody levels may present with, or evolve into, more focal or restricted presentations.

Autoimmune autonomic ganglionopathy with late-onset encephalopathy.

A 47-year old female presented with a 4 month history of early satiety, constipation, light sensitivity, orthostatic intolerance, siccca, and anhydrosis. Her examination revealed dilated, unreactive pupils with dry eyes and mouth but normal strength, phasic reflexes, and sensation. After 3 min of quiet standing her systolic pressure dropped 70 mmHg with a fixed heart rate of 74 bpm. Her alpha3 ganglionic AChR level was 2060 pmol/L (normal < or = 50). Orthostatic symptoms significantly improved within 10 days of completing 2.0 g/kg IVIg. Her supine norepinephrine (NE) level improved over baseline but remained low (i.e., 0.36 à 0.61 nmol/L). Persisting gut inertia prompted a trial of plasma exchange (PLEx) which restored her supine NE level (2.18 nmol/L), bowel patterns, and pupillary reactivity. Five months later, while her AAG was well controlled, she developed gait unsteadiness, confusion, horizontal and vertical nystagmus, bladder retention, and long tract motor signs. A contrast MRI head was normal. Further serum testing demonstrated binding avidity for neuronal alpha4 and alpha7 nAChRs. She responded to high-dose steroid and immunomodulation. This is the first case report of AAG presenting with antibodies directed against both peripheral and central nAChRs. It is tempting to speculate that CNS alpha4 or alpha7 antibodies may have precipitated the treatment-responsive encephalopathy.