Autonomics and Hypothalamus

Autonomic Insufficiency Syndrome

Key s/s of orthostatic hypotension, bowel/bladder dysfunction, impotence and sweating abnormalities

Horner’s Syndrome

This condition can arise from Cervical spinal cord injuries OR Lateral medullary syndrome

cerebral cortex

As the bladder fills, information about bladder fullness is relayed to the _________. The commands for micturition are issued as follows: frontal lobe → pontine micturition center (Barrington’s Nucleus) → thoracolumbar and sacral spinal cord.

sympathetics (L1-2)

promote storage: relax the detrusor and contract the internal sphincter

parasympathetics (S2-4)

promote release: contract the detrusor and relax the internal sphincter

somatic (pudendal nerve, S2-4)

voluntary control of skeletal muscle sphincters

Filling and holding phase

sympathetic + pudendal n (contracts voluntary sphincters)

Emptying phase

parasympathetics + relaxation of the voluntary sphincters

Stress incontinence

Signs/symptoms: leakage of small volume of urine with activities that increase intra-abdominal pressure (coughing, sneezing, bending over). Causes: weak sphincters — Neurogenic: trauma to pudendal n, spinal stenosis (weak voluntary sphincters); rare in men but may occur after pelvic surgery OR Loss of structural support of bladder neck and urethra (i.e. weakened pelvic floor – vaginal deliveries), may be associated with cystocele

Overflow incontinence

Signs/symptoms: involuntary emptying/leaking of an overfull bladder - frequent (and sudden) leakage of small volume of urine and (~painful) urinary retention (high residual volume). Causes: Neurogenic: impaired parasympathetic function, weak detrusor (dilated bladder, poor urine stream + incomplete emptying), difficulty in initiation of the micturition reflex (HYPOREFLEXIA, overfilling) and overflow; diabetic/autonomic neuropathy (prostatectomy), multiple sclerosis, spinal cord injury (+spinal shock). OR Structural: chronic outlet obstruction in men (prostate issues)

Urge Incontinence

Signs/symptoms: frequent urge to urinate (urinary urgency) and inability to delay voiding = sudden incontinence (medium to large volume); bladder HYPER-REFLEXIA (bladder fills to a low volume and reflexively empties). Causes: detrusor hyperactivity & hyper-reflexia = involuntary bladder contractions & frequent urination, Over active bladder, Irritation (cystitis, stones, bladder carcinoma), Loss of supraspinal inhibition to spinal micturition circuits: stroke, multiple sclerosis, Alzheimer disease, Parkinson disease, spinal cord injury (with spinal cord injuries/pathology there can be detrusor-sphincter dyssynergia (when the detrusor contracts, the sphincter also contracts) that results in an obstruction; can also coexist with impaired contractility: urgency, weak flow, residual urine

Outlet obstruction

Signs/symptoms: urgency, increased urination frequency, nocturia, dribbling incontinence after voiding, weak stream, incomplete emptying (residual volume).  Causes: benign prostatic hypertrophy, prostate cancer, uterine fibroid, cystocele, urethral stricture

sensory neurogenic bladder

Result of damage to peripheral ANS routes, can’t sense fullness/reduced urge: areflexia = overflow incontinence and urinary retention (infection risk!)

motor neurogenic bladder

Result of damage to peripheral ANS routes, normal sensation; flaccid bladder (increased capacity), areflexia (cannot empty bladder) = overflow incontinence; painful urinary retention of urine and impaired emptying because the detrusor cannot contract = infection risk!

Peripheral ANS damage

Can be caused by: trauma, tethered cord syndrome, lesions to cauda equina/conus medullaris, spinal stenosis, disc herniation, neuropathies, tabes dorsalis, diabetes mellitus, pelvic surgery (prostate)

parasympathetic innervation

loss of _______ following destruction of sacral spinal cord: overflow incontinence

voluntary control

loss of_______ following destruction of sacral spinal cord: stress incontinence

Sacral spinal cord

Destruction of ____ leads to loss of parasympathetic innervation, loss of voluntary control, intact sympathetic innervation, flaccid bladder (impaired emptying, increased capacity, urinary retention/distension (infection risk!)) + loss of urgency. Can be caused by trauma, conus medullaris syndrome, neural tube defects (spina bifida, etc), sacral syringomyelia

above lumbo-sacral segments

spinal cord injury ________ = S/S: bladder is initially flaccid and AREFLEXIC but becomes (after days to weeks) HYPER-REFLEXIC with increased tone and decreased capacity = the bladder fills to a low volume and reflexively empties. There is detrusor-sphincter dyssynergy = involuntary detrusor contractions without relaxation of the external urethral sphincter. Can be caused by multiple sclerosis, spinal cord trauma, syringomyelia, tethered cord syndrome

Brainstem injury

flaccid paralysis that becomes spastic (urge incontinence, hyperactive, empties too frequently)

Cortical injury (paracentral lobule)

loss of voluntary cortical control: uninhibited, spastic/hyperactive bladder

nocturnal enuresis

Urination during the night. Caused by abnormal changes in bladder pressure?, delayed maturation of bladder; small bladder, possible link to ADH secretion? Overactive detrusor

erection

parasympathetic (S2-4) for vascular smooth muscle; pudendal (S2-4) for contraction of perineal muscles

emission

sympathetic (L1-2) for contraction of smooth muscle in ductus deferens

ejaculation

sympathetic (L1-2) for closure of internal urethral sphincter; parasympathetics (S2-4) for contraction of urethral smooth muscle and pudendal (S2-4) for contraction of perineal muscles

prostatic plexus

Autonomic nerves concerned with erection traverse the _______ (at risk during prostate surgery!) and cavernous nerves.

Spinal cord/CNS injury above T11

Reflexive erections: intact (circuit from pudendal nerve to sacral parasympathetic column is intact); Psychogenic erections: rare (depends on severity of injury; requires intact circuit from frontal lobe to cord); Spontaneous erections: intact but variable; Ejaculation: reflexive, possible

Spinal cord injury below T12

Reflexive erections: not possible if S2-4 circuit is disrupted; Psychogenic erections: possible but variable; requires intact circuit from frontal lobe to cord; Spontaneous erections: rare; depends on severity of injury; Ejaculation: rare

Retrograde ejaculation

caused by dysfunction of the urethral sphincter during ejaculation and results in reflux of seminal fluid into the bladder (instead on flowing into the urethra); may result from ANS dysfunction of numerous etiologies (diabetes, spinal cord injury, demyelinating disease, prostate/pelvic surgery, side effects of medications for high blood pressure or mood disorders)

Respirations

______ are controlled in the lower brainstem: medulla (dorsal and ventral respiratory groups, near solitary nucleus) and pons (parabrachial nucleus); these nuclei project to the phrenic nucleus at C3-5

Brainstem lesions/strokes

________ may be accompanied by abnormal respirations (e.g. Cheyne-Stokes)

Cushing’s Disease

ACTH-secreting pituitary adenoma

LH or FSH-secreting adenoma

s/s are hypogonadism and infertility

Kallmann Syndrome

underproduction of GnRH → low levels of testosterone/estrogen. Males: delayed puberty, underdeveloped testicles, micropenis; Females: delayed puberty, amenorrhea; Anosmia/hyposomia

Prolactin-secreting adenoma

s/s are amenorrhea in women, hypogonadism in men; galactorrhea, infertility, hair loss, decreased libido and weight gain in both sexes

Diabetes Insipidus

Lesion of the neurohypophysis. Lack of vasopressin and polyuria, polydipsia

Syndrome of Inappropriate Antidiuretic Hormone Secretion [SIADH]

ADH secretion; Characterized by concentrated urine with an osmolality above 300 mosm/L; If treated with rapid infusion of hypertonic saline → central pontine myelinolysis

Panhypopituitarism

Deficiencies of all pituitary hormones

Craniopharyngioma

Calcified, epidermal tumor derived from remnants of Rathke’s pouch. s/s are visual loss, diabetes insipidus, adiposity, developmental delay, headaches, papilledema

Precocious Puberty

abnormally early onset of androgen or estrogen secretion; hypothalamus or tumor of pineal, testes, adrenals or ovary

VM nucleus

“satiety center” in _______; lesion = overeating

VL nucleus

“appetite center” in _______; lesion = failure to eat

Gigantism

Excess GH in childhood

Acromegaly

Excess GH after closure of epiphyseal plates

preoptic area

Lesions of _______ = hyperthermia (by disruption of heat-dissipating mechanisms)

posterior hypothalamus

Lesions in _________ = hypothermia