Dialysis Disequilibrium Syndrome

Definition

Definition of Dialysis Disequilibrium Syndrome
In nephrology, dialysis disequilibrium syndrome, commonly abbreviated DDS, is the occurrence of neurologic signs and symptoms, attributed to cerebral edema, during or following shortly after intermittent hemodialysis.

Classically, DDS arises in individuals starting hemodialysis due to chronic renal failure and is associated, in particular, with "aggressive" (high solute removal) dialysis. However, it may also arise in fast onset, i.e. acute, renal failure in certain conditions.

Symptoms

Symptoms of Dialysis Disequilibrium Syndrome
The symptoms of DDS are caused by water movement into the brain, leading to cerebral edema. Two theories have been proposed to explain why this occurs: a reverse osmotic shift induced by urea removal and a fall in cerebral intracellular pH.

Causes

Causes of Dialysis Disequilibrium Syndrome

1. Cerebral edema resulting from urea removal from the blood more rapidly than from the CSF and brain tissue generating a urea osmotic gradient responsible for water moving into brain cells.
2. HD generates a CO2 gradient between plasma and CSF lowering the pH in the CSF and brain tissue.
   This change will promote an increase in brain cell osmolality due to the rise in H+ concentration and the in-situ generation of osmols (acid radicals from protein metabolism) resulting in brain edema.

Diagnosis

Diagnosis of Dialysis Disequilibrium Syndrome
Clinical signs of cerebral edema, such as focal neurological deficits, papilledema and decreased level of consciousness, if temporally associated with recent hemodialysis, suggest the diagnosis. A computed tomography of the head is typically done to rule-out other intracranial causes.

Treatment

Treatment of Dialysis Disequilibrium Syndrome
Dialysis must be discontinued until the seizure and vital signs have been stabilized. Antiepileptic drug (AED) therapy may help to reduce seizures. A drug not removed by dialysis should be selected.

Most often, phenytoin is used. It is effective for tonic-clonic and partial seizures, and it can be given intravenously in loading doses to maintain a desired plasma concentration (e.g., after hemodialysis). Therapy begins with a loading dose of intravenous phenytoin (15-20 mg/kg). After dialysis, additional intravenous loading doses of phenytoin may be administered, if necessary. (See Correction for drug loss during hemodialysis).

Prognosis

Prognosis of Dialysis Disequilibrium Syndrome
Consult with your doctor.

Prevention

Prevention of Dialysis Disequilibrium Syndrome
Hypocalcemic seizures may be controlled with calcium gluconate.