Introduction

   It has been reported that movement disorders including akinetic mutism, tremor, dystonia and chorea could develop in hydrocephalus,⁹⁾ only a few cases of parkinsonism associated with hydrocephalus have ever been described in the literature.^{1)3)4)10)12)13)14)} We experienced a case of parkinsonism with hydrocephalus those clinical presentation was masked before cerebrospinal fluid(CSF) diversion.

Case Report

   A 42-year-old man was admitted due to progressive mental deterioration, apathy, urinary incontinence, poor oral intake and gait disturbance. He had undergone a craniotomy for ruptured anterior communicating artery aneurysm about one month before. He had neither focal neurological deficits other than above symptoms nor clinical features corresponding movement disorders. Brain CT showed dilatation of the ventricles with periventricular low densities and loss of gyral marking indicating increased intracranial pressure(Fig. 1A). Those symptoms were considered to be caused by the hydrocephalus. Ventriculo-peritoneal shunting was performed with a Medtronic PS medical low pressure flow control valve.
   After shunt operation, the patient showed a gradual improvement of symptoms of hydrocephalus such as urinary incontinence, gait disturbance and memory disturbance. CT scans revealed a shrinkage of the ventricles and the proximal catheter tip was placed appropriately(Fig. 1B). Three days later, the patient presented gradual swallowing difficulty, dysphonia, drooling and masked face. He had the clinical features of Parkinson's disease such as cogwheel rigidity in left upper extremity, slowness in initiation and execution of movements, festination, reduced spontaneous movements, dysarthria and sialorrhea. There was no symptom like resting tremor, respiratory insufficiency, psychological symptoms except mild depression associated with symptom of dysphagia.
   CT and Magnetic resonance imaging(MRI) scans were repeatedly performed but failed to show any sign of the shunt malfunction or abnormal finding(Fig. 2). Serum thyroid hormone, muscle enzyme and ionized calcium level were all within normal limit. The other laboratory data showed no combined systemic illness. Consult to psychiatric and dental department confirmed that there is no association with major depressive disorder or intrinsic mastication muscle problem. 
   SPECT(single-photon emission computed tomography) images of the brain showed reduction of radioisotope uptake in right basal ganglia which represented relative low perfusion in corresponding lesion(Fig. 3). Levodopa/carbidopa (Sinemet^® 250/25 mg P.O. TID) was challenged under diagnosis of parkinsonism. Initial Unified Parkinson's Disease Rating Scale was corresponded to a score of 49 and became 7 two weeks later after medication. He had made marked improving progress in speed of movement, facial expression, verbal output, dysphagia and slowness of walking. At discharge, the patient could independently complete his basic activities of ambulation and diet.

Discussion

   There were several reports about parkinsonism caused by normal pressure hydrocephalus(NPH),⁷⁾¹³⁾ obstructive hydrocephalus due to idiopathic aqueductal stenosis^1)10)14) and NPH accompanied by special disease such as empty-sella syndrome.¹¹⁾
   The pathophysiology of hydrocephalus inducing parkinsonism is still poorly understood. However, several possible pathophysiologic mechanisms were introduced. It has already suggested that parkinsonism associated hydrocephalus may be presented as the result of dysfunction of the nigrostriatal dopaminergic system or damage to those system favored by underlying weakness of the basal ganglia due to hydrocephalus.⁴⁾⁷⁾ Corticostratial and/or thalamocortical connections in the basal ganglia system would be involved.⁶⁾ Possible causes of this insult to basal ganglia probably combined mass effect^2)7)14) by enlarged ventricles and varying degree of ischemia.¹³⁾ Direct immediately reversible compression of the basal ganglia has been speculated to exert an inhibitory effect upon dopamine release, thus resulting in a parkinsonian syndrome.^2)7)14) And chronic intermittent mild hydrocephalus may cause temporary levodopa deficiency reversible over a period of weeks or months.¹⁴⁾ Recurrent basal ganglia and midbrain compression due to hydrocephalus can therefore cause an extrapyramidal and pretectal syndrome either by direct pressure or more chronically by impairment of blood flow to neuronal transport in the striatum resulting in dopamine deficieny which gradually reversible with time.²⁾⁴⁾⁷⁾
   As mentioned above in our case, brain SPECT of this patient demonstrated decreased regional cerebral blood flow(rCBF) in the right caudate and putamen. Decrease in CBF might be caused by distortion of the periventricular vessels due to ventricular dilation and the increase in blood flow resistance caused by compression of the arteriolar and venular blood vessels.⁵⁾¹¹⁾ It has been announced that dopamine has a vasodilatory effect on the striatal vessels, increasing local blood flow.⁸⁾ Thus marked improvement after dopamime administration is convinced that this isotope tracer finding may be correlated with his clinical presentation. Also, decreased perfusion in basal ganglia may probably have influenced on cerebral metabolism in nigrostriatal system.¹⁰⁾
   Parkinsonism usually occurred many months or years after the initial presentation of hydrocephalus and often followed repeated episodes of shunt failure.^1)10)14) However, in our case, there was initial clinical improvement after shunt operation, then subsequently he had parkinsonian features with no evidence of shunt failure that suggest comparatively short period of hydrocephalus. Usually stretch reflex or rigidity in this syndrome is bilateral but this case showed marked rigidity on unilateral extremity as two cases in previously reported.⁷⁾¹⁰⁾
   Previously reported cases of this syndrome had good prognosis, usually with total, or near total, resolution with the administration of dopaminergic therapy^1)3)10)14) although some cases responded to shunting alone.¹²⁾¹³⁾ From these data it can be assumed that there are two types of causal relationship between hydrocephalus and parkinsonism. One is hydrocephalus with parkinsonian features just as a clinical presentation of hydrocephalus which improve after shunt,¹²⁾¹³⁾ and the other is parkinsonism caused by hydrocephalus which need dopaminergic prescription with or without shunt.^1)4)10)14) Krauss et al. reported in a prospective study about adult hydrocephalus presenting movement disorders,⁹⁾ thirteen of 118 patients(11%) presented with a Parkinsonism, which consist of parkinsonism secondary to NPH in five patients and the other coexisted with Parkinson's disease. Our case would be included in former group. There is less possibility of preexisting Parkinson's disease in this case because that there were no significant symptoms or signs of Parkinson's triad before developing of hydrocephalus. His memory disturbance and bladder dysfunction improved after shunting, while the new parkinsonian symptoms had been raised and the patient continues to be dependent on dopaminergic therapy. This clinical course suggests that newly developed parkinsonian features were aggravated by altered CSF dynamics and were masked because of more severity of the symptoms of hydrocephalus. Although the question has been remained whether preexisting preclinical Parkinson's disease could predispose to the development of hydrocephalus even though he was in a high risk group for hydrocephalus after aneurymal subarachnoid hemorrhage. It could not be ruled out that concurrence could be possible through a threshold phenomenon；preclinical Parkinson's disease might be unmasked by active hydrocephalus.⁹⁾ 

Conclusion

   This report illustrates a patient with hydrocephalus who present hypokinetic movement disorder or has clinical feature like parkinsonism. If a patient with hydrocephalus develops clinical features of parkinsonism and those symptoms are not improved even after shunt operation without any evidence of shunt malfunction, the possibility of hydrocephalus induced parkinsonism-like syndrome should be considered.

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