Clinical characteristics of and treatment strategy for hydrocephalus in patients with severe disorders of consciousness

Making an appropriate diagnosis and effective treatment for hydrocephalus in patients with severe disorders of consciousness (DOC) remains controversial and difficult. Given that the typical symptoms are usually concealed by the limited behavioral responsiveness of patients with severe DOC, hydrocephalus diagnosis is likely to be missed in the clinic. Even if not, the presence of hydrocephalus may reduce the likelihood of DOC recovery, posing a conundrum for clinicians. From December 2013 to January 2023, the clinical data and therapeutic schedule of hydrocephalus in patients with severe DOC at Huashan Hospital's Neurosurgical Emergency Center were studied retrospectively. Sixty-eight patients [mean age (± SD) 52.53 ± 17.03 years, 35 males and 33 females] with severe DOC had been included. The hydrocephalus was discovered after computerized tomography (CT) or magnetic resonance imaging (MRI) revealed enlarged ventricles in the patients. During the hospitalization, the patient underwent a surgical treatment that included a ventriculoperitoneal (V-P) shunt and/or cranioplasty (CP) implantation. Following the surgery, an individualized V-P pressure was established based on the patient's ventricle size and neurological function variation. To account for the improvement in consciousness in patients with severe DOC, the Glasgow Coma Scale (GCS) and the Coma Recovery Scale-Revised (CRS-R) assessments were performed before and after hydrocephalus treatment. All severe DOC patients have varying degrees of ventricular enlargement, deformation, and poor brain compliance. Approximately 60.3% (41/68) of them had low- or negative-pressure hydrocephalus (LPH or NegPH). 45.5% (31/68) of the patients had a one-stage V-P shunt and CP operation performed concurrently, while the remaining 37 patients had a single V-P shunt operation performed independently. Beside of two DOC patients developed surgical complications, 92.4% (61/66) of the survivors showed an improvement in consciousness after hydrocephalus treatment. In patients with severe DOC, LPH or NegPH was common. Secondary hydrocephalus in DOC patients had been largely ignored, hampering their neurological rehabilitation. Even months or years after the onset of severe DOC, active treatment of hydrocephalus can significantly improve patients' consciousness and neurological function. Meanwhile, this study summarized several evidence-based treatment experiences of hydrocephalus in patients with DOC.

Intraoperative monitoring of CSF pressure in patients with degenerative cervical myelopathy (COMP-CORD Study): a prospective cohort study

Degenerative cervical myelopathy (DCM) is hallmarked by spinal canal narrowing and related cord compression and myelopathy. CSF pressure dynamics are likely disturbed due to spinal canal stenosis. The study aims to investigate the diagnostic value of continuous intraoperative CSF pressure monitoring during surgical decompression. Prospective single center study (NCT02170155) with enrolment of DCM patients that underwent surgical decompression between December 2019 and May 2021. Data from N=17 patients were analyzed, symptom severity graded with the modified Japanese Orthopedic Score (mJOA). CSF pulsations were continuously monitored with a lumbar intrathecal catheter during surgical decompression. Mean patient age was 62±9 years (range 38-73; 8F), symptoms were mild-moderate in most patients (mean mJOA 14±2, range 10-18). Measurements were well tolerated without safety concerns. In 15/16 (94%) CSF pulsations increased at the time of surgical decompression. In one case, responsiveness could not be evaluated for technical reasons. Unexpected CSF pulsation decrease was related to adverse events (i.e., CSF leakage). Median CSF pulsation amplitudes increased from pre-decompression (0.52 mmHg [IQR 0.71]) to post-decompression (0.72 mmHg [IQR 0.96]) (P=0.001). Mean baseline CSF pressure increased with lower magnitude than pulsations, from 9.5±3.5 to 10.3±3.8 mmHg (P=0.003). Systematic relations of CSF pulsations were confined to surgical decompression, independent of arterial blood pressure (P=0.927) or heart rate (P=0.102). Intraoperative CSF pulsation monitoring was sensitive, timely, and specifically related to surgical decompression while in addition adverse events could be discerned. Further investigation of the clinical value of intraoperative guidance for decompression in complex DCM surgery is promising.

Studies on acute disseminated encephalomyelitis produced experimentally in rhesus monkeys

The white cell count, total protein, gamma globulin, and percentage of gamma globulin in the cerebrospinal fluid of monkeys with acute disseminated encephalomyelitis produced by the injection of brain emulsions with adjuvants have been studied. The acute phase of the disease is characterized by a rise in the white cell count, total protein, and gamma globulin in the cerebrospinal fluid. In some instances the percentage of gamma globulin, to the total protein may be normal while in others it is elevated. As the acute process subsides, the total protein declines and animals frequently show an increase in the percentage of gamma globulin to total protein. The relation of the cerebrospinal fluid findings in acute disseminated encephalomyelitis in the rhesus monkey to those in human multiple sclerosis is discussed.

Blood clotting factors in cerebrospinal fluid

The activity of blood clotting factors has been investigated in cerebrospinal fluid. No cephalin-like activity was found in cerebrospinal fluid but prothrombin activity averaged about 0.5% of normal plasma activity. The activity of factor VII was negligible in almost all cases. The activity of antihaemophilic factors showed great variation but in the majority of cases it did not exceed 1% of normal plasma activity. High activity for factor V was found in almost all samples of cerebrospinal fluid.

Stimulation and sensitization of the isolated Venus heart by cerebrospinal fluid

5-Hydroxytryptamine was not detected in animal cerebrospinal fluid after amine oxidase inhibitors, reserpine, or both. Both human and animal cerebrospinal fluid can produce a stimulating effect on the clam heart which is not due to 5-hydroxytryptamine. Cerebrospinal fluid also has the property of increasing the sensitivity of the clam heart to 5-hydroxytryptamine.

Cerebrospinal fluid production and its relationship to cerebral metabolism and cerebral blood flow

The cerebrospinal fluid production has been studied in the dog under conditions of maximum obtainable flow rates from the cisterna magna. Under these conditions the fluid had constant composition and was assumed to represent the cerebrospinal fluid in the intact state. Cerebral blood flow and cerebral oxygen consumption were measured by the method of Kety and Schmidt. The only significant correlations found were with oxygen consumption when the CSF flow rate was in terms of brain weight and with cerebral blood flow and cerebral vascular resistance when CSF flow was in terms of choroid plexus weight. A combined regression equation was calculated which satisfactorily accounted for the observed CSF flow: CSF cu mm/min. = .128 x CMRO2 x brain wgt. + 0.15 x CVR x choroid plexus wt. This suggested separate physiological processes, one correlated with oxygen metabolism and one with hydrodynamic factors of the cerebral blood flow. The data demonstrated that the choroid plexus alone could not have accounted for the entire CSF flow and some must have come from another source, presumably the brain.

Urea transport in the central nervous system

The kinetics of urea transport in the central nervous system have been studied in rabbits during sustained intravenous and intracisternal infusions of C12 and C14 urea. The steady state content of urea in the water phase of the white matter and cord was approximately equal to its content in plasma water. However, the water of whole brain and gray matter had levels of urea which exceeded those in plasma by 7 and 18%, respectively, whereas the urea in cerebrospinal fluid (CSF) was only 78% of the plasma level. Its rate of penetration into nervous tissue was approximately one-tenth as rapid as into muscle. The intravenous infusion of urea caused a significant decrease in water content of the brain and cord. It was estimated that urea infused into the subarachnoid space penetrated the central nervous system (CNS) tissues at four to five times the rate of transport from blood to CNS tissues. These studies suggest that intravenous infusions of urea lower CSF pressure by decreasing the volume of the brain and cord. The major barrier to urea penetration into nervous tissue is at the capillary level, and not the plasma membrane of the glial or neuronal cells.