Autonomic dysfunction is a hallmark feature of hereditary ATTR amyloidosis. The aim of this study was to summarize the characteristics and natural history of autonomic dysfunction in patients with hereditary ATTR amyloidosis.
A systematic review of the natural history and clinical trials of patients with ATTR amyloidosis was performed. Alternative surrogate markers of autonomic function were analyzed to understand the prevalence and outcome of autonomic dysfunction.
Patients with early-onset disease displayed autonomic dysfunction more distinctively than those with late-onset disease. The nutritional status and some autonomic items in the quality-of-life questionnaires were used to assess the indirect progression of autonomic dysfunction in most studies. Gastrointestinal symptoms and orthostatic hypotension were resent earlier than urogenital complications. Once symptoms were present, their evolution was equivalent to the progression of the motor and sensory neuropathy impairment.
The development of autonomic dysfunction impacts morbidity, disease progression, and mortality in patients with hereditary ATTR amyloidosis.

Transthyretin (TTR)-related amyloidosis (ATTR) is a devastating disease which affects a combination of organs including the heart and the peripheral nerves, and which has a fatal outcome if not treated within a average of 10 years. Tafamidis, or 2-(3,5-dichloro-phenyl)-benzoxazole-6-carboxylic acid, selectively binds to TTR with negative cooperativity and kinetically stabilizes wild-type native TTR and mutant TTR; tafamidis therefore has the potential to halt the amyloidogenic cascade initiated by TTR tetramer dissociation, monomer misfolding, and aggregation. The first tafamidis trial, Fx-005, evaluated the effect of 18 months of tafamidis treatment (20 mg once daily) on disease progression, as well as assessing its safety in TTR-FAP Val30Met patients. The secondary objective of this trial was to study the pharmacodynamic stabilization of mutated TTR. Tafamidis proved effective in reducing the progress of neuropathy, and in maintaining the nutritional status and quality of life of stage 1 (able to walk without support) Val3OMet TTR-FAP patients. Furthermore, TTR stabilization was achieved in more than 90% of patients. An extension study, Fx-006, was conducted to determine the long-term safety and tolerability of tafamidis and to assess the efficacy of the drug on slowing disease progression. No significant safety or tolerability issues were noticed. Taken together, the results from both trials indicated that the beneficial effects of tafamidis were sustained over a 30-month period and that starting treatment early is desirable. Results are expected from an extended open-label study but data that have already been presented show that long-term use of tafamidis in Val30Met patients is associated with reduced progression in polyneuropathy. Tafamidis was initially approved for commercial use in Europe in 2011 and has since been approved for use in Japan, Mexico, and Argentina where it is used as a first-line treatment option for patients with early-stage TTR-FAP. Patients should be carefully followed at referral centers to ascertain the individual response to treatment. In cases of discontinuation, liver transplantation and enrollment in clinical trials of novel drugs aimed mostly toward suppression of TTR production are options.

Improvement of therapeutic strategies for peripheral neuropathies requires multicentric clinical trials. For chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), a randomized controlled multicentric study compared IgIV to pulses of methylprednisolone (MP) given for 6 months. The primary endpoint was treatment discontinuation due to inefficacy or intolerance; 45 patients were enrolled: more patients had interrupted MP than IVIg, usually because of inefficacy. A multicentric randomized clinical trial (PREDICT) evaluated long-term remission of CIDP after short-term corticosteroid therapy (pulses of dexamethasone or prednisolone); 39 patients were enrolled: 26% achieved cure or remission, a relapse occurred in 50% after a delay of 11 to 17 months. Differential diagnosis was identified in 58% of patients who had not responded to any therapy. For refractory CIDP, a retrospective study showed the possibility of functional improvement in 24% of cases after adjunction of an immunomodulatory agent; cyclosporine was associated with the highest rate of adverse events or side effects. In familial amyloidotic polyneuropathy, a multicentric controlled study against placebo with tafamidis, an akinetic stabilizer of transthyretin (TTR) 20mg/d, in early stage of Val30MetTTR showed efficiency in the evaluable group and led to marketing authorization by the EMA in stage 1 to slow the progression of the neuropathy. A Cochrane database system review showed that there are no randomized or quasi-randomized controlled clinical trials of treatment for POEMS syndrome, for neuropathies with anti-MAG antibodies, or multifocal motor neuropathy on which to base practice. This review underlines the usefulness of multicentric randomized trials to assess treatments in peripheral neuropathies.