Pathogenesis of hepatic myelopathy
Hepatic myelopathy is a rare neurological complication as the spinal cord lesion in the later period of liver cirrhosis, clinical manifestation of which is spastic paraplegia, enhancement muscular power of two lower limbs, tendon hyperreflexia and positive pyramidal sign. This syndrome was reported firstly by Leigh and Card in 1949. In 1960, Zieve[1] in detail described the nervous pathological change of hepatic myelopathy by autopsy, and proposed that hepatic myelopathy is a demyelinated changes of pyramidal in the spinal cord.
The pathogenesis of hepatic myelopathy is correlative with severe hepatic cirrhosis (decompensate stage), the portosystemic split-flow, hepatic encephalopathy and blood ammine increase. It is the pathogenesis basis of demyelinated changes of pyramidal in spinal cord that is insufficiency of liver detoxication, which causes blood ammine increase, harmful substances and metabolism producers of protein without detoxication entering systemic circulation by the portosystemic split-flow. Hyperammonemia has a harmful effect on nervous system. The liver disease can cause metabolism disturbance of Vitamin B.
The two patients had the above characteristics: ① severe hepatic cirrhosis (decompensate stage); ② one patient had undergone splenectomy before 7 years, which caused the portosystemic split-flow severely; ③ hepatic encephalopathy was caused after upper gastrointestinal bleeding repeatedly; ④ broad form between portsystemic circulation; and ⑤ hyperammonemia.
Clinical manifestation of hepatic myelopathy
Hepatic myelopathy occurred in the later stage of all kinds of the liver cirrhosis. It is the main pathogenesis that the central nervous system was injured by harmful substances as the portsystemic split-flow[2]. The clinical manifestation includes two aspects: the former is the manifestation of liver cirrhosis (especially decompensate stage); the latter is the manifestation of neurous system as character of spastic paraplegia, which includes lower limbs tiredness, muscle stiff, walking difficulty, two knees adduction, two feet drooping and spastic gait. The muscular strength of two lower limbs was descended obviously. But the muscular tension was raised, the tendon reflex showed sthenia, knee or heel jerk and pathological reflex appeared positive. The reflexes of the abdominal reflex and the cremasteric were weakened or disappeared in the severe patient. The above symptoms are worse progressively and are not remitted normally, so as caused spastic paraplegia or limbsparalysis. The amyotrophy could be not seen normally. The deep or superficial sensation is normal, but the pallesthesia position sense is abnormal in a few patients, or with peripheral nervous lesion. But the sphincter function is not disturbed.
The syndrome was divided into three stages as the clinical manifestation: firstly, nervous presymptomatic stage, which mainly displayed as liver damage. Split-flow formed due to collateral circulation or post-shunt. Secondly, repeatedly encephalopathy stage: the main clinical manifestation is transient or repeated sense disturbance and mental symptom, such as emotional abnormality (euphoria, excitation and so on), behavior disturbance (unconsciousness hyperactivity and so on), intelligence abnormality (hypomnesia and disorientation), mental disturbance (paraphasia, confusion and mania), parasympathetic nerve symptoms (abnormal perspiration, tachycardia, skin redness and cold feeling in hand/foot), and the other neurous symptoms (dysarthria, asterixis, gutta serena and so on). Thirdly, spastic paraplegia stage: spastic paraplegia appeared, which the complete or uncomplete limbs paraplegia was. A few patients have pseudobulbarpalsy as the pyramidal tract lesion. It is worth noticing the imbalance in the spinal and brain symptom. The brain symptom was repeated and transient. The spinal symptom appeared slowly and progressively worse, exhibits extend spastic paraplegia in early stage and flexion spastic paraplegia in later stage.
Diagnosis and treatment of hepatic myelopathy
Hepatic myelopathy is rare, but the diagnosis is not difficult. ① the history of chronic hepatopathy or liver cirrhosis; ② repeated paroxysmal hepatic encephalopathy; ③ broad portosystemic collateral circulation and/or the history of portacaval shunt, splenectomy, lienectomy of stamach fundus-esophagus vein; ④ spastic paraplegia, without obvious hypomyotonia, amyotrophy and paraesthesia; ⑤ hyperammine; ⑥ cerebrospinal fluid normal and/or protein rise slightly; ⑦ except for multiple sclerosis, Wilson disease, spinal space occupying lesion, amyotrophic lateral sclerosis and so on.
There is not an effective method for treating hepatic myelopathy. The medical treatment includes restriction of protein intake, control of enteric bacteria growth, improvement of liver function, employment of decendens amminine agents and nerve cell nutrient agent[3]. The operation had been reported by the abroad scholar, which were colic free operation or ileal-rectal anastomosis for decreasing poisons intake. This operation could reduce blood amminine in a short period and improve the neurous symptom, but the satisfied effect could not be got, thus, the prognosis was poor[4-5]. Treatment of the liver disease can improve the symptom in the mild spastic paraplegia. However, hepatic myelopathy is the syndrome of irreversible and progressive spastic paraplegia, which normally appeared worse progressively. About 90% of patients would lose their walking function. As the progress of spastic paraplegia was slow, the hepatic myelopathy could not threaten patients’ life directly. The prognosis of hepatic myelopathy mainly depends on the degree of liver cirrhosis. A majority of patients would die of complications, including hepatic coma, upper gastrointestinal bleeding, hepatorenal syndrome, infective shock, canceration, pulmonary infarction, respiratory palsy, cerebral hemorrhage, or gastric perforation as gastric ulcer at 2-3 years after hepatic myelopathy.
Effect of liver transplantation on the recovery of hepatic myelopathy
For many years, doctors have been striving to find an effective therapeutic method for hepatic myelopathy. As the liver function of these patients has normally been in the end period, the treatments could only postpone the progress. There is not a decisive method for this syndrome. The liver transplantation is a new therapeutic method from the pathogen. The liver transplantation not only can solve decompensation of liver function, but also clean the toxic substances effectively, which can recover the homeostasis of body. This is an effective therapeutic method, which could not be replaced by the other therapeutic methods. As we know, if the nervous system was injured, the recovery period would be long and difficult. The improved degree was positively correlated with the interval between hepatic myelopathy and the liver transplantation[6].
Here, the two patients both could stand at 6 months after liver transplantation and walked with the aid of the supporter after 12 months. Currently, one patient could walk slowly without the supporter at 43 months after transplantation. The results show that liver transplantation has received an obvious therapeutic effect on treating hepatic myelopathy. However, the cases involved in this study were few, and the time observation was short, thus, the long-term effect still needs to be assessed progressively.
