Atrial natriuretic peptide response to postural change and medication in familial dysautonomia

A review of the oro-dento-facial characteristics of hereditary sensory and autonomic neuropathy type III (familial dysautonomia)

The oro-dento-facial features and dysfunction of children with hereditary sensory and autonomic neuropathy type III, known as familial dysautonomia or Riley-Day syndrome, was first described in the scientific literature in 1949. They include dental trauma; dental and soft tissue self-mutilation; normal dental age; normal sequence and timing of eruption and exfoliation of teeth; smaller tooth size; different and disproportional tooth components; normal alveolar bone height; small jaws, mild crowding, and malocclusions. These persons have craniofacial morphology that is different from accepted norms but they resemble norms of their ethnic origin. The subjects can have gray, pale, shiny faces with an asymmetric suffering expression; frontal bossing, with eventual hypertelorism and narrow lips; a low-caries rate; drooling, and hypersalivation. They can have changes in salivary composition and content, which influences plaque and calculus and increases the risk of gingival and periodontal diseases. They also have difficulty in controlling oral muscles; a progressive decrease in number of tongue fungiform papillae, accompanied by lack of taste buds; and specific dysgeusia, but a normal sense of smell.

A world without pain or tears

The world of the child with familial dysautonomia (FD), a genetic disorder affecting development of the sensory and autonomic nervous system, is not idyllic. However, over the last 35 years advances in supportive treatments have improved morbidity and mortality. Recent genetic breakthroughs have further expanded thinking about this disorder and suggested innovative approaches to modifying genetic expression. This article reviews the current supportive treatment modalities and their rationale, as well as the suggested new treatments that may alter the function and prognosis of an individual affected with FD.

Anesthesia management of familial dysautonomia

Familial dysautonomia (FD) is an autosomal recessive inherited disorder, predominantly affecting the Ashkenazi Jewish population that is characterized by sensory and autonomic neuropathy. The protean manifestations and perturbations result in high morbidity and mortality. However, as a result of supportive measures and centralized care, survival has improved. As surgical options are increasing to symptomatically treat FD, anesthesiologists need to be familiar with this disorder. Because the Dysautonomia Center at NYU Medical Center is a referral center for FD patients, we have attained considerable anesthetic experience with FD. This article reviews clinical features of FD that could potentially affect anesthetic management and outlines our present practices.

Familial dysautonomia: a review of the current pharmacological treatments

Treatment of familial dysautonomia, a genetic disorder affecting neuronal development and survival, has improved morbidity and survival for this disorder. Although this is primarily a neurological disorder causing sensory and autonomic dysfunction, there are secondary systemic perturbations affecting ophthalmological, gastrointestinal, respiratory, cardiovascular, orthopaedic and renal function. Penetrance is complete, but there is marked variability in expression. Preventative and supportive treatments have included measures to maintain eye moisture, fundoplication with gastrostomy, the use of central agents such as benzodiazepines and clonidine to control vomiting and the dysautonomic crisis, and fludrocortisone and midodrine to combat cardiovascular lability. With the identification of the familial dysautonomia gene, it has been suggested that it may be possible to treat patients by modifying production and expression of the genetic product.

Recurrent syncope, hypotension, asthma, and migraine with aura: role of metoclopramide

Migraine associated with asthma or symptomatic orthostatic hypotension is a particularly difficult subgroup to manage. Metoclopramide is a useful pharmacological agent for orthostatic hypotension. I present the case report of a migraine patient with asthma and recurrent hypotensive syncope. Metoclopramide relieved recurrent syncope as well as migraine attacks in this patient. Metoclopramide has a striking influence on arginine vasopressin (AVP) secretion. AVP promotes antinociception and influences vasomotor and behavior control, which actions possibly keep migraine in remission. Further studies are necessary to confirm the migraine prophylactic value of metoclopramide.

Assessing Efficacy of High-Frequency Chest Wall Oscillation in Patients With Familial Dysautonomia

STUDY OBJECTIVE

To determine the benefits of daily use of high-frequency chest wall oscillation (HFCWO) in familial dysautonomia (FD) patients with lung disease.

DESIGN

Pulmonary function tests, chest radiographs, and blood tests were performed on entry to the study. A retrospective chart review of 12 months prior to entry provided baseline data regarding respiratory illnesses, medications, doctor visits, hospitalizations, and absenteeism. Daily logs provided prospective data on these parameters as well as HFCWO usage. Evaluations were performed at 1, 3, 6, 9, and 12 months for pulse oximetry, spirometry, and log review. At the exit evaluation, blood tests and chest radiographs were repeated.

PATIENTS

Fifteen FD patients with history of lung disease requiring daily inhalation therapy (7 female and 8 male; age range, 11 to 33 years) were enrolled in a 1-year clinical trial of HFCWO therapy. Two subjects withdrew after 3 months and 6 months, respectively. Each individual served as his/her own control.

RESULTS

Oxygen saturation improved by 1 month (median, 97.5%; interquartile range [IQR], 96 to 98%; vs median, 94%; IQR, 89 to 96%) and was sustained at exit evaluation (median, 98%; IQR, 98 to 98%) [p = 0.004]. Median FVC and peak expiratory flow rate (PEFR) were the pulmonary function measures with sustained improvement from baseline to exit (p = 0.02 and p = 0.03, respectively). When retrospective and prospective data were compared, all measured health outcomes improved significantly, including pneumonias (p = 0.0156), hospitalizations (p = 0.0161), antibiotic courses (p = 0.0005), antibiotic days (p = 0.0002), doctor visits (p = 0.0005), and absenteeism (p = 0.0002).

CONCLUSION

In this limited study of FD patients, HFCWO effected significant improvements in all measured health outcomes and oxygen saturation; FVC and PEFR were the pulmonary function measures demonstrating sustained improvement.

Familial dysautonomia

Familial dysautonomia (FD) is a neurodevelopmental genetic disorder within the larger classification of hereditary sensory and autonomic neuropathies, each caused by a different genetic error. The FD gene has been identified as IKBKAP. Mutations result in tissue-specific expression of mutant IkappaB kinase-associated protein (IKAP). The genetic error probably affects development, as well as maintenance, of neurons because there is neuropathological and clinical progression. Pathological alterations consist of decreased unmyelinated and small-fiber neurons. Clinical features reflect widespread involvement of sensory and autonomic neurons. Sensory loss includes impaired pain and temperature appreciation. Autonomic features include dysphagia, vomiting crises, blood pressure lability, and sudomotor dysfunction. Central dysfunction includes emotional lability and ataxia. With supportive treatment, prognosis has improved greatly. About 40% of patients are over age 20 years. The cause of death is usually pulmonary failure, unexplained sudden deaths, or renal failure. With the discovery of the genetic defect, definitive treatments are anticipated.

Respiratory and cerebrovascular responses to hypoxia and hypercapnia in familial dysautonomia

Although cardiorespiratory complications contribute to the high morbidity/mortality of familial dysautonomia (FD), the mechanisms remain unclear. We evaluated respiratory, cardiovascular, and cerebrovascular control by monitoring ventilation, end-tidal carbon dioxide (CO2-et), oxygen saturation, RR interval, blood pressure (BP), and midcerebral artery flow velocity (MCFV) during progressive isocapnic hypoxia, progressive hyperoxic hypercapnia, and during recovery from moderate hyperventilation (to simulate changes leading to respiratory arrest) in 22 subjects with FD and 23 matched control subjects. Subjects with FD had normal ventilation, higher CO2-et, lower oxygen saturation, lower RR interval, and higher BP. MCFV was also higher but depended on the higher baseline CO2-et. In the FD group, whereas hyperoxic hypercapnia induced normal cardiovascular and ventilatory responses, progressive hypoxia resulted in blunted increases in ventilation, paradoxical decreases in RR interval and BP, and lack of MCFV increase. Hyperventilation induced a longer hypocapnia-induced apneic period (51.5 +/- 9.9 versus 11.2 +/- 5.5 seconds, p < 0.008) with profound desaturation (to 75.8 +/- 3.5%), marked BP decrease, and RR interval increase. Subjects with FD develop central depression in response to even moderate hypoxia with lack of expected change in cerebral circulation, leading to hypotension, bradycardia, hypoventilation, and potentially respiratory arrest. Higher resting BP delays occurrence of syncope during hypoxia. Therapeutic measures preventing hypoxia/hypocapnia may correct cardiovascular accidents in patients with FD.

Dermal microdialysis provides evidence for hypersensitivity to noradrenaline in patients with familial dysautonomia

OBJECTIVES

To use the technique of dermal microdialysis to examine sensitivity of skin vessels to noradrenaline (NA) in patients with familial dysautonomia (FD) and in healthy controls.

METHODS

In 14 patients with FD and 12 healthy controls, plasma extravasation, local laser Doppler blood flow, and skin blanching were observed before, during, and after application of 10(-6) M NA through a microdialysis membrane, located intradermally in the skin of the lower leg.

RESULTS

Maximum local vasoconstriction measured by laser Doppler blood flow did not differ between patients with FD and controls. In contrast, patients with FD had an earlier onset of vasoconstriction (p = 0.02). Moreover, reaction to NA was more prominent and prolonged in FD, shown by a larger zone of skin blanching around the microdialysis membrane (p < 0.001) and delayed reduction of the protein content in the dialysate after termination of NA application (p = 0.03).

CONCLUSION

These data support the hypothesis that peripheral blood vessels of patients with FD show a denervation hypersensitivity to catecholamines. This may be one mechanism contributing to the major hypertension that frequently occurs during "dysautonomic crises" in FD.

Sympathetic and parasympathetic pupillary dysfunction in familial dysautonomia

Objective assessment of autonomic dysfunction in familial dysautonomia (FD) is largely based on the analysis of cardiovascular responses to challenge maneuvers such as orthostatic stress. Infrared pupillometry (IPM) provides an additional reliable method for cranial autonomic evaluation and has the advantage of requiring minimal cooperation.This study was performed to determine whether IPM contributes to the assessment of autonomic function in FD patients. In 14 FD patients and 14 healthy controls, we studied absolute and relative light reflex amplitude, pupillary constriction velocity (v(constr)), pupillary diameter, early and late pupillary re-dilatation velocity (v(dil 1), v(dil 2)) after dark adaptation. Prior to IPM, all patients had an ophthamological examination to evaluate refraction and corneal integrity. In comparison to controls, patients had a significant reduction of the parameters reflecting parasympathetic pupillary function (absolute light reflex amplitude 1.34 +/- 0.21 vs. l.86 +/- 0.14 mm, relative light reflex amplitude 22.74 +/- 7.11% vs. 30.76 +/- 3.57%, v(constr) 3.75 +/- 1.09 vs. 5.80 +/- 0.59 mm/s) and of the parameters reflecting sympathetic pupillary function (diameter 5.69 +/- 0.66 vs. 6.35 +/- 0.60 mm, v(dil 1) 1.29 +/- 0.23 vs. 1.95 +/- 0.23 mm/s, v(dil 2) 0.64 +/- 0.13 vs. 0.72 +/- 0.l2 mm/s; Mann-Whitney U-test: p<0.05). The non-invasive technique of IPM demonstrates dysfunction not only of the cranial parasympathetic, but also of the cranial sympathetic nervous system and, thus, further characterizes autonomic dysfunction in FD.

Intranasal midazolam as a treatment of autonomic crisis in patients with familial dysautonomia

To evaluate the efficacy and safety of intranasal midazolam in the treatment of autonomic crises in children with familial dysautonomia, intranasal midazolam was administered at the hospital to six patients during nine episodes of autonomic crisis. Treatment was successful in seven of nine episodes of autonomic crisis in five of six patients, with a mean interval to response of 9.25 +/- 1.25 minutes. The parents of five patients in whom the treatment was successful were instructed to use midazolam at home. At home, 16 additional episodes were treated by the parents, with successful control achieved in 14 (87%). The mean interval to response was 12.8 +/- 2 minutes. No significant side effects were observed at the hospital or at home after intranasal administration of midazolam. Midazolam, given intranasally, is effective and safe in the management of autonomic crises in patients with familial dysautonomia, either in the hospital or at home by the parents after appropriate instruction.

Assessing microcirculation in familial dysautonomia by laser Doppler flowmeter

Microcirculatory vasomotor responses to an alpha-adrenergic agonist and an antagonist were assessed in 11 familial dysautonomia and nine control subjects by laser Doppler flowmetry. Using two iontophoresis machines, blood flow in the midclavicular areas was continuously monitored by two channel laser Doppler flowmeter. Simultaneously, the alpha-antagonist (0.5 mM phentolamine hydrochloride) and a control solution (0.9% saline) were iontophoresed at 200 microA for 15 min. The alpha-agonist (0.5 mM norepinephrine bitartrate) was then iontophoresed (20 microA) to both pretreated areas for progressively longer pulses separated by 3-min observation intervals (15, 30, 60, 90, 120 s). The familial dysautonomia subject group had higher mean baseline perfusion with widely fluctuating baselines, especially on the phentolamine pretreated side (P = 0.03). Saline iontophoresis significantly increased perfusion in the control group, but not in the familial dysautonomia group (ANOVA: P = 0.02 and 0.15, respectively). There was > 100% increase in flow by the end of the saline observation period in seven of nine controls, but in only three of 11 familial dysautonomia subjects. Phentolamine iontophoresis differentiated familial dysautonomia subjects into responders and nonresponders by 7-8 min when all nine control subjects, but only five of 11 familial dysautonomia subjects, had > 200% increase in blood flow. Irrespective of pretreatment type, norepinephrine decreased blood flow in both familial dysautonomia and control groups (ANOVA: P < 0.0001), but the final mean change after saline was greater in the control group, P = 0.02. The final mean changes of flow after phentolamine pretreatment were not different between the two groups and were comparable to the familial dysautonomia group's smaller response after saline pretreatment. Higher baseline perfusion suggests dilation may be intrinsic to familial dysautonomia vasculature. Two populations of familial dysautonomia subjects are noted; those who like controls increase blood flow with iontophoresis of the alpha-antagonist and those who are refractory. In addition, in familial dysautonomia subjects, the microcirculatory constrictive response to alpha-agonist iontophoresis is less than that observed for controls. These data suggest that some familial dysautonomia subjects may have decreased or dysfunctional adrenoceptors as well as decreased innervation.

Pattern of plasma levels of catecholamines in familial dysautonomia

This report extends previous investigations of endogenous catecholamine levels in patients with orthostatic hypotension due to familial dysautonomia (FD), to define better the neurochemical phenotype and elucidate possible pathophysiological mechanisms. Ten FD patients (age 26.1 +/- 2.6 (SEM) years) and eight control subjects (age 29.5 +/- 3.7 years) were studied. Heart rate, blood pressure and venous blood samples were obtained while supine and after 5 min in the upright position. Plasma levels of dihydroxyphenylalanine (DOPA), noradrenaline (NA), adrenaline (A), dopamine (DA), dihydroxyphenylglycol (DHPG) and dihydroxyphenylacetic acid (DOPAC) were measured. When supine, the FD group had greater NA and DOPA levels, and lower DHPG levels. Plasma NA did not increase with erect posture in FD patients. Individual FD mean blood pressures were correlated positively with plasma NA levels when supine and with plasma DA and DOPAC when upright. In FD, DOPA:DHPG ratios were above the range found in normal subjects or that reported in patients with acquired forms of dysautonomia regardless of posture, whereas DOPAC:DHPG ratios remained normal. Thus FD patients have a characteristic neurochemical pattern which probably reflects either decreased vesicular storage of catecholamines or limited oxidative deamination despite normal or increased tyrosine hydroxylation.