Hydrocephalus - click Posttraumatic Hydrocephalus, a 2006 chapter in eMedicine by Scott Strum, MD.

The most common, treatable neurosurgical complication following TBI, can be detected by bedside measurement of head circumference or MRI, but must then be divided into one of two types: communicating, the most common following TBI, and noncommunicating.

1. Communicating Hydrocephalus, in which the different portions of the ventricular system are interconnected and CSF may exit the ventricular system to the cisterns and subarachnoid space
   • Symptoms of communicating hydrocephalus in TBI:
     • Enlargement usually involves all portions of the ventricular system
     • Elevated ICP may or may not be present. If present, there is usually headache, nausea, vomiting, lethargy, or decreasing mental status
     • Dementia
     • Urinary incontinence
     • Gait ataxia, in which there is decreased cadence, step height, and shoulder conterrotation relative to the pelvis, and an abnormal tendency to muscle contraction
     • Loss of upgaze
     • Akinetic mutism
     • Worsening or failure to progress adequately
     • Presence of meningitis, intracranial hemorrhage, or hypertension

   • Diagnosis:
     • CT scans of ventriculomegaly that show:
       • Enlargement of temporal horns, the third ventricle and its recesses during the first month postinjury
       • Convex shape of frontal horns, with widening of frontal horn radius and narrowing of ventricular angle
       • Progressive ventricular enlargement on serial CT scans
     • MRI scans show:
       • More anatomic detail, such as the Sylvian aqueduct and the foramen of Monro, as well as the fornix and corpus callosum (Ashikaga, et al 1997)
       • More sensitivity for transependymal fluid, which appears as an increased periventricular signal on T2-weighted imaging and which may be useful in determining treatment
         • Smooth, symmetric periventricular signal is more likely to respond to shunting
         • Irregular, asymmetric signal may be seen with demyelination or infarction due to longstanding hydrocephalus or unrelated causes
       • A better assessment of CSF flow and oscillation
       • SPECT and PET scans may be of value in determining periventricular flow. Improved flow can indicate a good outcome from shunting, whereas a low flow can indicate a poor outcome
       • Lumbar puncture may be of value:
         • To measure CSF pressure to determine treatment, e.g. pressure <100 mmHg can be a contraindication for shunting
         • To remove 40-50 ml of CSF to determine treatment, e.g. improvement in neurologic status indicates a potential for improvement with shunting
       • Radioisotope cisternography to determine ventricular pooling
       • Placement of a ventricular catheter may be of value to:
         • Monitor pressure and determine treatment, e.g. presence of B waves >5-10% of the time may indicate good outcome with shunting
         • Measure CSF absorption by infusing liquid via a lumbar or ventricular catheter and measuring drainage via a ventricular catheter and determine treatment, e.g. high CSF absorption indicates a shunt is not needed and will not help, whereas low CSF absorption indicates a shunt may help
       • Transcranial Doppler to detect decreased blood flow or increased pulsatility may be a useful screening procedure prior to invasive testing

   • Treatment:
     • Shunts - Placement of ventriculoperitoneal shunts in most cases, or ventriculoatrial, ventriculopleural, or lumboperitoneal shunts in some cases. Outcome following shunt implantation is mixed, with the best results occurring in patients with a good pre-operative status (Tribl and Oder, 2000). Symptomatic post-traumatic hydrocephalus patients are likely to improve when treated by shunting (Guyott & Michael, 2000). Complications of shunting can include:
       • Shunt failure or obstruction, the most common problem
         • Signs include rapid onset of headache, irritability, confusion, lethargy, and abdominal pain
         • Causes include proximal and distal occlusion, and, less frequently, valve failure
         • Treatment includes aspiration or transplanting the distal shunt
       • Infection, usually acquired during surgery, which can be diagnosed with tapping and treated with antibiotics and/or shunt removal or replacement
       • Seizures, although they may be due to an accompanying neurologic condition, and not the shunt
       • Problems due to overdrainage, such as subdural hematoma, hygroma, low-pressure syndrome, and slit ventricle syndrome, which may require tying off of the shunt or placing a higher pressure valve
     • Lumbar puncture if shunting is not indicated

2. Noncommunicating Hydrocephalus, in which there is obstruction, either between the ventricles or in exiting the ventricular system
   • Symptoms - enlargement usually involves only certain portions of the ventricular system, such as large lateral and third ventricles only, or unilateral hydrocephalus, which may occur with occlusion of the foramen of Monro
   • Diagnosis - injected contrast dye and MRI to confirm flow of CSF; lumbar puncture should be avoided
   • Treatment - stereotactic fenestration or placement of shunt catheters