An increasing number of case analyses have focu-sed on the diffusion-weighted image (DWI)-negative stroke, specifically those correlated with posterior circulation ischemia or a small brainstem infarct¹. A common manifestation is dysphagia, a stroke-related symptom, that is associated with a poor prognosis post-stroke². Cricopharyngeal dysfunction (CPD) is a disease in which excessive tension of the upper eso-phageal sphincter appears in the pharyngeal phase of swallowing; it is known to cause dysphagia. The presence of CPD in a DWI-negative infarct can also play a crucial role in distinguishing a unilateral brain-stem lesion.

Video fluoroscopic swallowing studies (VFSS) have been performed for dysphagia in stroke patients, but no previous studies have focused on the natural course of CPD from its onset to resolution at short intervals. This study reports CPD in the patient with acute DWI-negative stroke and serial swallowing functional changes through VFSS.

The study participant provided informed consent. A 71-year-old man with a history of hypertension and myocardial infarction visited the gastroenterology de-partment for sudden-onset dysphagia that occurred 3 days prior. The patient refused a diagnostic evaluation and was prescribed medication for gastroesophageal reflux disease (GERD).

The patient visited the emergency room 6 days later with aspiration pneumonia, dysphagia, and dys-arthria, but there was no sore throat. Physical exa-mination revealed a decreased gag reflex, decreased hyolaryngeal excursion, delayed hyolaryngeal move-ment, and hoarseness. There were no signs of invol-vement of other cranial nerves or sensory and motor impairments in the limbs. Initial laboratory analysis revealed a high white blood cell (WBC) count of 12.4× 10³/μL and a high neutrophil count of 9.17×10³/μL. Laryngoscopy revealed left arytenoid mild swelling and hypomobility of the left vocal cord. Asymmetric thickening of the aryepiglottic fold was observed on neck computed tomography.(Fig. 1A) Acute lesions were not observed on brain magnetic resonance ima-ging.(Fig. 1B)

Figure 1. CT and MRI imaging results. (A) Neck CT shows asymmetric thic-kening of the left aryepiglottic fold (white arrow). (B) No definite acute lesion was shown in Brain MRI. Bra-in Diffusion Weighted Image (at admission). (C) Brain T2-FLAIR Image (10 days after admission). CT: computed tomography, MRI: magnetic re-sonance imaging, FLAIR: fluid attenuated inversion recovery.

On the 5th day following hospital admission, labo-ratory analysis revealed a normal WBC count of 7.1× 10³/μL and a normal neutrophil count of 4.37×10³/μL. On the 9th day following hospital admission, the first VFSS was performed, and the videofluoroscopic dys-phagia scale (VDS) was used to score the outcome³. In the pharyngeal phase, a delayed swallowing reflex, a large amount of residue in the vallecular fossa, impaired pharyngeal peristalsis, and decreased lary-ngeal elevation were observed. When he swallowed 5 cc of semi-solid food, significant pre- and post- swallowing aspirations were detected without coug-hing.(Fig. 2) The VDS score was 60 points.(Table 1) On the 10th day following hospital admission, a followup laryngoscopy was performed. Compared to previous laryngoscopy findings, mild swelling of the arytenoid persisted, and there were no findings suggestive of pharyngeal cancer. On the 12th hospital day post-admission, a follow-up brain magnetic reso-nance imaging showed no specific findings.(Fig. 1C) Nerve conduction studies and electromyography findings suggested left ulnar and median neuropathies, but no abnormal results were correlated with other causes of dysphagia. Among the various diseases that need to be differentially diagnosed, the course of the patient’s disease was too rapid and not progressive, so motor neuron disease was thought to be unlikely. Since dysphagia persisted even after all inflammation levels improved, the possibility of acute stroke with sudden- onset of dysphagia was considered to be higher than infection or inflammation. An acute stroke with sudden-onset dysphagia was condisdered as the possible cause of dysphagia.

Table 1 . Serial follow-up findings of the videofluoroscopic swallowing study.

Parameters of VDS (Time from symptom onset)	Initial VFSS (14 days)	Second VFSS (28 days)	Third VFSS (2 months)	Third VFSS with head positioning	Fourth VFSS (4 months)	Fourth VFSS with head positioning
Lip closure	0	0	0	0	0	0
Bolus formation	UC†	0	0	0	0	0
Mastication	UC†	0	0	0	0	0
Apraxia	0	0	0	0	0	0
Tongue-to-palate contact	0	0	0	0	0	0
Premature bolus loss	0	0	0	0	0	0
Oral transit time	0	0	0	0	0	0
Triggering of pharyngeal swallow*	4.5	4.5	0	0	0	0
Vallecular residue	6	6	6	2	2	0
Laryngeal elevation*	9	0	0	0	0	0
Pyriform sinus residue*	13.5	9	4.5	0	4.5	0
Coating on the pharyngeal wall	9	9	9	9	9	9
Pharyngeal transit time*	6	6	0	0	0	0
Aspiration	12	12	12	0	12	0
Total VDS score*	60	46.5	31.5	11	27.5	9

VFSS: videofluoroscopic swallowing study, VDS: videofluoroscopic dysphagia scale..

*Improved parameters in the follow-up VFSS..

^†UC: Uncheckable parameters as the study was halted over safety concerns of massive aspiration in the process of VFSS with a small amount of semi-solid..

Figure 2. The first video fluoroscopic swallowing study findings. (A) Pre-swallowing aspiration (arrow). (B) Post-swallowing aspiration (arrow).

On May 24th, 2022, the second VFSS showed mild improvement in the swallowing reflex and persistent moderate CPD. The VDS score was 46.5 points. From the anteroposterior view, the bolus was tolerated, and aspiration signs disappeared as the head was turned to the left and tilted to the right, indicating the role of a lateralizing lesion in symptom onset.(Fig. 3) Before the oral feeding initiation, Mendelsohn’s ma-neuver was performed. On June 28th, 2022, in contrast to the previous examinations, the third VFSS showed an improvement in CPD. The VDS score was 31.5 points when the head was in a neutral posture and 11 points when the head was in a specific pos-ture.(Fig. 4) Thus, the nasogastric tube was removed, and complete oral feeding was initiated. On August 23rd, 2022, the last VFSS showed gradual improve-ment in the vallecula and pyriform sinuses, as well as resolution of aspiration at a specific head posture. The VDS score was 27.5 points when the head was in a neutral posture, and 9 points when the head was in a specific posture.

Figure 3. The second video fluorosco-pic swallowing study findings show improvement in a specific position. (A) Lateral view with a neutral head position. (B) AP view with the head turned to the left and tilted to the right. (C) Lateral view with the head turned to the left and tilted to the right. AP: anteroposterior.

Figure 4. The third video fluorosco-pic swallowing study findings show improvement in a specific position. (A) Lateral view with a neutral head position. (B) AP view with the head turned to the left and tilted to the right. (C) Lateral view with the head turned to the left and tilted to the right. AP: anteropo-sterior.

This case report presented the natural resolution course for dysphagia in a patient with a DWI- negative stroke based on serial VFSS results. These findings can provide clues linking the mechanisms and the resolution course of CPD.

CPD can be caused by cerebral infarction, esopha-geal muscle enlargement, changes in nerve signaling pathways, scarring of the muscle, radiation, trauma, or GERD⁴. In the presence of CPD in a DWI-negative infarct, this can also be key to differentiating a uni-lateral lesion of the brainstem. According to a recent meta-analysis, DWI-negative infarct rates ranged from 4.9% to 9.3%, most of which occurred in the brain-stem and cerebellum⁵. Dysphagia in patients with a brainstem stroke presents with pharyngeal asymmetry, pharyngeal motility impairment, and CPD. The inci-dence of dysphagia in patients with a brainstem stroke is 70%, which is severe enough to require non-oral feeding. After an aggressive rehabilitation program, more than 80% of these patients resumed full oral feeding at long-term follow-up⁶.

The American Academy of Neurology has published that DWI has a sensitivity of 88% to 100% for ischemic infarction, making it essential for achieving the most accurate diagnosis of an ischemic stroke¹. However, it has been reported that the DWI-negative acute infarction syndrome exhibits stroke-related symptoms and is often associated with three major types: poste-rior circulation ischemia, small stroke specifically in the brain stem, and hyperacute ischemia¹. Even in the study by Chalela et al.⁷, which reported the advan-tages of acute stroke imaging diagnosis using MRI, false-negative DWI results, which are challenging to differentiate, did not separate brain stem lesions from surrounding artifacts and were not identified in sub-sequent examinations. Based on the symptoms and progression, these cases were diagnosed as stroke- related symptoms, and the patients reported two main factors: the presence of a brain stem lesion and an National Institutes of Health Stroke Scale (NIHSS) score less than 4⁷. In this case, the patient had the initial NIHSS score of only 2, indicating severe dysarthria, without any motor weakness at the initial assessment.

In this case, there exists a constraint in definitively confirming the diagnosis of dysphagia attributed to DWI-negative stroke; nevertheless, it is being regarded as one potential causative factor. Acute ischemic stroke symptoms caused by negative DWI are easily missed at the onset of illness, and delay in diagnosis and management can lead to lethal complications such as silent aspiration and malnutrition due to dysphagia. Following the diagnosis and acute mana-gement of stroke, early rehabilitation for dysphagia may result in significant improvement among patients with DWI-negative stroke. There is a need to esta-blish the significance of intensive dysphagia rehabili-tation including neuromuscular electrical stimulation therapy in patients clinically diagnosed with an acute stroke. Therefore, further case studies involving a larger population of patients with DWI-negative stroke with obvious acute symptoms of stroke, presenting with dysphagia, are warranted.

There are no conflicts of interest to declare.

None.

Hyun Woo Cho: Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Project administration, Resources, Validation, Visualization, Writing – original draft, review & editing.

Min Seung Kim: Data curation, Formal analysis, Investigation, Methodology, Project administration, Resources, Supervision, Writing – review & editing.

Yeon Jun Kim: Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Project administration, Resources, Validation, Visualization, Writing – review & editing.

Yeong Jae Kim: Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Project administration, Resources, Validation, Visualization, Writing – review & editing.

Soo Jin Jung: Data curation, Formal analysis, Investigation, Methodology, Project administration, Resources, Supervision, Writing – review & editing.

Jihyun Park: Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Project administration, Resources, Validation, Visualization, Writing – review & editing.