Co-occurrence of Binswanger dementia with vascular Parkinsonism – A case report

INTRODUCTION AND BACKGROUND

Parkinsonism is known to be caused by a neurodegenerative process; however, the possibility of vascular mechanisms causing Parkinsonism has been entertained in medical literature. This condition, namely, vascular Parkinsonism (VP), is distinct from the idiopathic (sporadic) Parkinsonism, as it primarily exhibits gait abnormality. Binswanger disease is a slowly progressive, non-hereditary form of vascular cognitive impairment with cerebral small vessel changes such as thickening and narrowing of arteries in the brain, resulting in extensive white matter lesions (WML) and gradual subcortical ischemia. It is seen in elderly patients with dementia presenting with a prominent gait abnormality and, hence, was also known as “lower half Parkinsonism.” It is the second most common form of dementia after Alzheimer’s disease and is projected to increase in numbers among the geriatric population.^[1] The symptomatology of cognitive impairment, gait disturbances, focal neurological deficits, and urinary incontinence runs a close differential with other neurological conditions such as normal pressure hydrocephalus (NPH) and stroke,^[2,3] thereby making it pertinent to differentiate between the same.

VP was used to describe a clinical phenotype that predominantly consisted of a gait abnormality associated with a vascular pathogenesis affecting the subcortical white matter.^[4] Apart from WML, other brain lesions with a vascular pathogenesis were also known to cause VP. There are several case reports suggestive of unilateral Parkinsonian features seen following a brainstem ischemia, suggestive of stroke-induced Parkinsonism.^[5]

CASE REPORT

A 74-year-old elderly gentleman with a background of multiple vascular risk factors, such as hypertension, diabetes, stroke, and smoking, presented with slowness while walking for 3 years, which was rapidly progressive in nature and associated with falls. Family members had also noted disturbances in his gait in the form of short, shuffling steps, and occasional freezing episodes. They reported that over the past few years, his speech seemed slower, softer, and effortful. He had also gradually developed a need for assistance while performing activities of daily living (ADL) as he seldom encountered difficulty in carrying out day-to-day tasks. Patient attendants also reported that he easily gets distracted while solving puzzles which he earlier used to enjoy doing. His previous medical history was significant for a hospital admission 3 years ago in view of an acute onset left-sided hemiparesis, which was diagnosed as a left thalamocapsular bleed and was managed conservatively. On examination, there was no postural drop in blood pressure, and the patient was hemodynamically stable. He was conscious and readily obeying commands. Systemic examination was positive for slow saccades, masked facies, grade 3 bradykinesia and rigidity in lower limbs more than the upper limbs with a residual left upper motor neuron facial palsy and residual left hemiparesis. A short shuffling gait was noted.

Our patient was also subjected to a detailed cognitive assessment with screening tools such as the Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA). MMSE assesses orientation, memory, attention, calculation, language, and praxis. An MMSE score <24 indicates mild cognitive impairment (MCI), whereas a score <18 is indicative of severe dementia. Our patient scored 28 out of a total 30 MMSE points which were well within normal limits. Being a more comprehensive and specific test that is particularly adept at identifying MCI, MoCA was also performed. Our patient scored a MoCA score of 25 out of a total 30 points (patient lost points in clock drawing – [Figure 1]), which raised the possibility of a cognitive impairment.

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Figure 1:

Image demonstrating results of cognitive assessment test (unable to copy the diagram of clock).

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VP presents with distinctive clinical features such as an acute onset, rapidly progressive gait abnormality, with pyramidal signs, pseudobulbar palsy, and cognitive impairment in the backdrop of vascular risk factors. The most predominant clinical feature comprises lower-body Parkinsonism, which presents with lower limbs predominant rigidity and gait abnormality. Since our patient exhibited a multitude of these characteristics, a diagnosis of VP was strongly entertained.

With the presence of urinary disturbance with a backdrop of gait and memory abnormalities, NPH was considered as a differential; however, it typically lacks features of bradykinesia and rigidity. Multisystem atrophy was also entertained as a possibility in light of autonomic dysfunction; however, lower-body Parkinsonism and lack of cerebellar involvement made it less likely. In the discussion of vascular dementia (VaD) with neurological deficits and progressive cognitive decline, it is pertinent to consider cerebral amyloid angiopathy (CAA) as a risk factor, although a definitive diagnosis can be made only through pathological examination of brain tissue at postmortem. In line with the above thought process, we proceeded with neuroimaging to narrow down a radiological diagnosis with the above clinical picture.

T2-weighted sequences of magnetic resonance imaging (MRI) brain showed small vessel ischemic changes with symmetrical, periventricular, and basal ganglia WML. Presence of disproportionately enlarged subarachnoid space hydrocephalus, corpus callosum thinning, and temporal horn dilation and other such features suggestive of NPH were excluded. T2 and fluid-attenuated inversion recovery (FLAIR) sequences also demonstrated Fazekas grade 3 periventricular white matter hyperintensities with irregular periventricular signals extending into the deep white matter [Figures 2-4]. Furthermore, the absence of microhemorrhages and/or ventricular dilatation made CAA and NPH unlikely. Conventionally, vascular lesions in the brain are necessary to make a diagnosis of VP. However, the presence of WMLs on MRI brain alone is insufficient to label a patient as VP, as these lesions are common among elderly individuals who are unaffected by Parkinsonism. Several studies have drawn correlations between the severity and extent of WMLs and progression of gait impairment.^[6]

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Figure 2:

Magnetic resonance imaging brain T2 imaging sagittal section shows diffuse cortical atrophy with enlarged sulcal spaces. Arrow represents for predominant cortical atrophy in fronto-parietal region associated with subcortical white matter hyperintensities favour cognitive decline that is executive dysfuction.

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Figure 3:

Magnetic resonance imaging brain axial section shows fluid-attenuated inversion recovery hyperintensities in periventricular and deep white matter – Fazeka grade 3. Extensive, confluent periventricular and deep white matter hyperintensities (black arrows).

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Figure 4:

Magnetic resonance imaging brain coronal section shows bilateral symmetrical patchy changes in bilateral cerebral periventricular and basal ganglia. White matter hyperintensities in the deep grey matter and periventricular regions which contribute to alteration of nigrostriatal pathways predisposing to parkinsonism (black arrows).

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The patient’s baseline neurological deficits were scored according to the Unified Parkinson’s Disease (PD) Rating Scale, while ensuring that he was not on any anti-Parkinsonian medication. 250 mg of Levodopa was administered, following which the patient was reassessed after 1 h and scored accordingly. Less than 10% improvement was noted in the motor symptoms, prompting the conclusion of a negative Levodopa challenge test. This further reinstated the possibility of VP. Patient was managed with a transdermal rivastigmine patch, piracetam, and other supportive care. All his risk factors and comorbidities were addressed and corrected. Gait and balance training given.

During the course of hospital stay, after initiation of rivastigmine and piracetam, patient and family members reported significant improvement in mobility; however, his memory impairment did not show any drastic changes since admission. Objective evidence of improvement was noted with the Timed Up and Go test which improved from over 30 s on presentation to 18 s at the time of discharge. However, a modified Rankin score of 3 was observed during the entire course of the hospital stay. Considering the age and limitations in ADL of the patient, family members were initially distressed at his condition; however having understood the risk factors and pathophysiology of the disease process of VaD and VP, they understood the limitations in reversing his neurological impairment. Patient and family members were thoroughly counseled regarding the need to manage his comorbidities to prevent further neurological decline. However, they were also made aware of certain medical interventions and supportive therapy such as cognitive and gait training techniques to better manage this condition. They were discharged with a consolidative follow-up plan.

The patient was reviewed in the outpatient department on a bimonthly basis for 6 months following discharge, after which he was lost to follow-up. First two OPD visits were inconsequential for cognitive and/or motor decline. However, the third visit revealed a MMSE score of 22/30 and a MOCA score of 24/30 which were a decline from the initial assessment at presentation. The motor deficits remained largely unchanged during our observed period of follow-up.

DISCUSSION

NINDS-AIREN diagnostic criteria for VaD reinstate the need to establish a temporal relationship between stroke and dementia onset for a secure diagnosis of Binswanger disease and the importance of brain imaging to support clinical findings.^[7,8]

On retracing our patient’s clinical history, the onset of slowly progressive memory and cognitive impairment coincided with a few months of a cerebrovascular accident that he had suffered, with documented neurological deficits and radiological findings on neuroimaging. Radiologic findings in Binswanger’s disease include subcortical and periventricular hyperintense lesions visible on FLAIR, T2-weighted, and proton-density sequences, moderate-diffuse cerebral atrophy, and lacunar infarcts in the basal ganglia and thalami. Clinical findings favoring Binswanger’s disease include evidence of systemic vascular disease, evidence of focal cerebrovascular disease, and “subcortical” cerebral dysfunction. Accordingly, our patient presented with a history of stroke, with MCI, severe executive dysfunction, supportive MRI brain features with early gait and urinary disturbances, which were strongly favoring a diagnosis of a VaD such as Binswanger’s disease. However, this case was intriguing as the patient also complained of rapidly progressive slowness of movements associated with falls and rigidity involving the lower limbs more than the upper limbs. The possibility of an overlap between VaD and lower-body Parkinsonism was considered.

VP is a form of atypical Parkinsonism, in which the Parkinsonian features are of vascular origin, in contrast to typical PD, which is neurodegenerative in etiology.^[9] Clinical diagnosis of VP can be made with the appearance of bradykinesia, rigidity, and postural instability within a year of clinical or neuroradiological evidence of cerebrovascular disease. Response to Levodopa in VP is uncertain;^[10] however, it is advisable to provide a trial with L-dopa in adequate dosage, for a sufficiently long period of time, before concluding an absence of response. Hence, our patient was given a trial of Levodopa with Carbidopa; however, no improvement of symptoms was noted. This unresponsiveness of VP to dopaminergic drugs helps differentiate it from idiopathic PD. Therefore, the crux of managing VP lies in addressing the vascular risk factors adequately to prevent its progression.

Binswanger’s dementia is a type of subcortical arteriosclerotic encephalopathy, associated with vascular risk factors such as hypertension, arteriosclerosis, and strokes. The disease usually presents between the 5^th to 7th decades, although exceptional presentation does exist^[11] and evolves with a step-wise or progressive decline in cognitive function. It involves executive functions such as attention deficit, changes in working and short-term memory with intact long-term memory, language, and visual-spatial functions. Patient usually presents with a history of stroke with neurological deficits, with a mixture of pyramidal, extra-pyramidal and pseudobulbar signs. On cognitive assessment, the MMSE score is often normal with the MoCA score indicating the possibility of cognitive impairment. The characteristic findings on neuroimaging include subcortical WMLs that present as large, white confluent hyperintensities on MRI. Binswanger dementia is a chronic, small vessel ischemia in the brain and presents with bilateral, symmetrical representation on neuroimaging. T2W1 and FLAIR sequences are significantly more sensitive imaging modalities compared to CT. Clinical evaluation and neurological assessment suggestive of cognitive decline (memory and executive dysfunction) and motor deficits such as gait disturbances with slowness of movements alongside radiological evidence of subcortical and periventricular WMLs satisfy the criteria for the diagnosis of Binswanger dementia. Management of this condition is variable and poses several limitations. Prevention and control of vascular risk factors such as hypertension play an important role. Symptomatic medication to address cognitive decline and motor deficit is limited and requires further research. Binswanger’s disease is irreversible and progressive, with no definitive cure. However, rehabilitation methods to improve cognitive and motor skills are essential in improving the quality of life of the patient. Therefore, therapeutic methods are individualized with a multi-modality approach with particular emphasis on patient education and motivation.

Binswanger’s disease and VP have overlapping clinical manifestations, risk factors, and neuroimaging findings, although they arise from a similar pathology. Little is known about the natural course of VP and VaD overlap^[12] caused by a small vessel disease; however, both of these are characterized by white matter damage due to small vessel ischemia secondary to vascular risk factors such as hypertension in Binswanger’s dementia and multiple small strokes and lacunar infarctions in VP. Small vessel changes and damage to basal ganglia and its related connections can present with Parkinsonian features. While VP can exist independently, it can also be seen as a part of Binswanger’s dementia.^[13] Overlapping clinical manifestations such as cognitive decline, gait disturbances, executive dysfunction, urinary disturbance, and Parkinsonian features are seen. WMLs can be seen on MRI in both conditions; however, more extensive lesions are seen in Binswanger’s disease. Another distinguishing feature between the two is the response to dopamine therapy seen in VP, although the response is less robust when compared to that with idiopathic PD.^[14]

We thereby report the case of an elderly gentleman with history of significant vascular risk factors, presenting with clinical features of cognitive impairment, gait disturbance, executive dysfunction and parkinsonian features. Radiological findings were consistent with that of Binswanger’s dementia. He showed good improvement with rivastigmine and piracetam,^[15] cognitive and gait rehabilitation, alongside strict control of risk factors.

CONCLUSION

This case demonstrated a rare overlap of Binswanger dementia with VP, with both of them stemming from a vascular origin. Since both of these conditions are stemming from the same entity and share similar risk factors and disease progression, patients should be counseled accordingly. For instance, a patient of Binswanger’s dementia should be made aware of his progressive cognitive decline, alongside the possibility of worsening gait abnormality. Similarly, a patient with features of lower-body Parkinsonism should be assessed for cognitive decline, alongside the physiologic process of aging.

Binswanger’s disease and VP cause loss of functional independence, thereby affecting the quality of life. Early diagnosis and prevention of risk factors play a key role in the management of the disease, alongside physiotherapy, gait training, and cognitive exercises.