Symptoms of autonomic dysfunction occur in many common conditions which affect both the parasympathetic and sympathetic pathways e.g. cerebrovascular disease.
The following arc less common disorders which primarily may affect the autonomic nervous system -
IDIOPATHIC ORTHOSTATIC HYPOTENSION
Two types of this condition are recognised:
1. Due to degeneration of sympathetic postganglionic neurons.
2. Due to degeneration of sympathetic preganglionic neurons of the intermediolateral column T1-T12 -SHY-DRAGER SYNDROME.
sphincter disturbance: pupillary abnormalities. The disorders may be separated pharmacologically; the postganglionic disorder shows hypersensitivity (denervation hypersensitivity) to noradrenaline infusion. Treatment
Drugs such as fludrocortisone increase blood volume and may prevent postural hypotension. DIABETIC AUTONOMIC NEUROPATHY
Bladder dysfunction - decreased detrusor muscle action - resulting in increased residual volume. Nocturnal diarrhoea.
G1 dysfunction - vomiting from gastroparcsis. Orthostatic hypotension.
These problems arise from damage to both sympathetic and parasympathetic postganglionic neurons. Treatment
Improve diabctic control and treat symptoms e.g. fludrocortisone for BP control.
POST-INFECTIOUS POLYNEUROPATHY - Guillain-Barré syndrome (see previous chapter). Autonomic involvement occurs commonly in this disorder and may present major problems in patient management. The lesion may involve the afferent or efferent limbs of the cardiovascular reflexes (baroreceptor reflexes) resulting in postural hypotension, episodes of hypertension and cardiac dysrhythmias. Occasionally the postinfectious neuropathy is purely autonomic.
HEREDITARY AUTONOMIC NEUROPATHY e.g. RILEY-DAY Syndrome
This autosomal recessive disorder occurs in persons of Jewish descent.
Features of autonomic dysfunction: postural hypotension, oesophageal reflux, hyperpyrexia - present from birth. Insensitivity to pain results with associated sensory neuropathy.
Autonomic involvement with orthostatic hypotension, impotence, diarrhoea and bladder involvement may accompany sensimotor neuropathy in the primary and hereditary forms. Amyloid infiltration affects autonomic ganglia.
A tonic pupil (page 140) associated with areflexia and occasionally widespread autonomic dysfunction, e.g. segmental hypohidrosis (absent sweating) and diarrhoea.
AUTONOMIC DYSFUNCTION IN QUADRIPLEGIA (autonomic dysreflexia)
A high cervical lesion which completely severs the spinal cord, e.g. traumatic cervical fracture/dislocation will isolate all but the cranial parasympathetic outflow. As a result, disturbed autonomic function is inevitable but variable.
Autonomic reflexes arc retained - Passive movement or tactile stimulation of limbs may result in blood pressure rise, bradycardia, sweating, reflex penile erection (priapism).
Pelvic nerves (nervi erigentes) \
i Hypogastric 4 nerve
bP,nal sphincter cord ^¿s
Function: somatic efferent
Detrusor muscle relaxation
Internal sphincter contraction
Hypogastric External Plexus sphincter ^^
Detrusor muscle contraction Internal sphincter relaxation
Origin: anterior horn cells S2,3,4 -Voluntary innervation corticai. control
Frontal lobe: paracentral lobe
- initiates micturition
- inhibits micturition
Afferent innervation parasympathetic sympathetic
Enter through posterior rami and terminate in anteromediolateral column T9-L2
Enter through \ posterior rami ^ and terminate in anterolateral \ column, S2,3,4.
Sensation of painful distension conveyed from bladder wall
Sensation of pain and distension conveyed from bladder wall and internal sphincter
The afferent pathways are responsible for the sensation of bladder fullness
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