The primary aim of this study is to evaluate the relationship between the CONUT score, which reflects nutritional status, and balance performance in patients with chronic stroke. The secondary aims are to investigate the association between the CONUT score and functional status and stroke-specific quality of life, as well as to assess the relationships of mid-upper arm circumference, an anthropometric indicator of nutritional status, and ultrasonographic rectus femoris muscle thickness, which reflects muscle mass, with balance performance, functional status, and stroke-specific quality of life. In addition, the study aims to examine the relationships between bone mineral density and balance, functional status, and ambulation level in patients with chronic stroke.

Stroke is a clinical syndrome characterized by rapidly developing neurological deficits resulting from the sudden interruption or reduction of cerebral blood flow and remains one of the leading causes of mortality and long-term disability among adults worldwide. Following the acute phase, a substantial proportion of patients transition to the chronic stage, during which persistent functional impairments such as motor deficits, balance disorders, gait limitations, and dependence in activities of daily living frequently occur.

During the post-stroke period, the risk of malnutrition increases due to factors such as dysphagia, immobility, reduced oral intake, increased catabolism, and muscle loss, all of which may negatively affect functional recovery and rehabilitation outcomes. In particular, deterioration of nutritional status in patients with chronic stroke has been reported to be associated with reduced muscle strength, impaired postural control, and increased dependence in activities of daily living.

Balance disorders in patients with chronic stroke are closely associated with reduced postural control, decreased muscle strength, and impaired sensorimotor integration. Impaired balance increases the risk of falls during the chronic phase of stroke, reduces walking speed, and limits functional independence. In addition, malnutrition characterized by decreased muscle mass and muscle function has been reported to have adverse effects on postural stability and balance performance. Therefore, evaluating the relationship between nutritional status and balance performance in patients with chronic stroke is of considerable importance for clinical management and rehabilitation strategies.

In the assessment of nutritional status, anthropometric measurements, in addition to biochemical markers, provide valuable information regarding muscle and fat tissue reserves. Mid-upper arm circumference is a simple and reliable anthropometric parameter reflecting muscle mass and peripheral tissue reserves, and it has been shown to be associated with nutritional status and functional outcomes in chronic diseases. Considering muscle loss related to immobility and asymmetric loading in stroke patients, the use of mid-upper arm circumference as a complementary indicator in evaluating the relationship between nutritional status and balance and functional status is clinically meaningful.

The Controlling Nutritional Status (CONUT) score, used to assess nutritional status, is an objective nutritional assessment index based on serum albumin level, total lymphocyte count, and total cholesterol concentration, reflecting not only nutritional status but also immunological and metabolic conditions. Although the CONUT score was initially developed for hospitalized patients, it has been shown to be associated with functional outcomes and mortality in patients with stroke. Evidence suggests that nutritional status may deteriorate from the acute phase through the chronic stage and remains clinically relevant even during the chronic phase of stroke.

In recent years, ultrasonography has increasingly been used in clinical research for the assessment of muscle mass because it is a non-invasive, radiation-free, and reproducible method. Ultrasonographic measurement of rectus femoris muscle thickness, an important antigravity muscle of the lower extremity, has been reported to be a valid and reliable indicator of muscle mass and peripheral muscle reserve and to show significant associations with muscle strength, balance performance, and walking capacity. In stroke patients, pronounced thinning of the rectus femoris muscle, particularly in the paretic lower extremity due to immobility, has been demonstrated, and this muscle loss has been associated with impaired postural control, reduced walking performance, and decreased functional independence.

During the post-stroke period, marked reductions in bone mineral density may occur due to immobility, decreased weight bearing, and reduced mechanical loading. This loss has been reported to be more pronounced on the paretic side and particularly in the hip and proximal femur regions. Loss of walking ability and low levels of weight bearing have been associated with accelerated bone mineral density loss, whereas preservation or recovery of ambulatory capacity may help limit this decline. These findings suggest that the relationship between balance, functional mobility, muscle status, and bone health may be clinically important in patients with chronic stroke.

In light of these findings, the primary aim of the present study is to evaluate the relationship between the CONUT score, reflecting nutritional status, and balance performance in patients with chronic stroke. The secondary aims are to investigate the association between the CONUT score and functional status and stroke-specific quality of life, as well as to evaluate the relationships of mid-upper arm circumference, an anthropometric indicator of nutritional status, and ultrasonographic rectus femoris muscle thickness, reflecting muscle mass, with balance performance, functional status, and stroke-specific quality of life. Additionally, the study aims to examine the relationships between bone mineral density and balance, functional status, and ambulation level in patients with chronic stroke.

Inclusion Criteria:

• Being 18 years of age or older
• Having a diagnosis of ischemic or hemorrhagic stroke
• At least 6 months having elapsed since the stroke event (chronic phase)
• Being clinically stable
• Being able to participate in standing and balance assessments (walking with an assistive device is acceptable)
• Having sufficient cognitive capacity to understand and respond to the assessment scales used in the study
• Voluntarily agreeing to participate in the study and providing written informed consent

Exclusion Criteria:

• Acute or subacute stroke phase (< 6 months)
• Inability to administer assessment scales due to severe cognitive impairment or aphasia
• Presence of other neurological disorders that may significantly affect balance and functional status (e.g., Parkinson's disease, multiple sclerosis, peripheral neuropathy)
• Significant orthopedic conditions unrelated to stroke (e.g., advanced hip or knee osteoarthritis, lower extremity amputation)
• Presence of active infection, malignancy, or systemic inflammatory disease (as these conditions may affect the CONUT score)
• Cerebellar localization of the cerebrovascular event
• History of major surgery or intensive care unit admission within the past 3 months
• Inability to safely perform balance tests due to severe visual or hearing impairment
• Patients with incomplete laboratory data or insufficient information to calculate the CONUT score

A total of 47 patients with chronic stroke, aged between 18 and 85 years, who were followed in the Physical Medicine and Rehabilitation and Neurology outpatient clinics of Marmara University Pendik Training and Research Hospital and met the study inclusion criteria.