Numbness of the Left Leg Caused by Perfusional Deficit in Right Parietal Lobe in a Case of Whiplash-Associated Disorder: Comparison of Imaging Tools for Diagnosis

Shan-Wen Lui; Kar-Wai Lui; Shin-Tsu Chang

doi:10.37871/jbres1978

ISSN: 2766-2276

General Science. 2024 August 16;5(8):983-988. doi: 10.37871/jbres1978.

Subject area(s)

Rehabilitation

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Case Report

Numbness of the Left Leg Caused by Perfusional Deficit in Right Parietal Lobe in a Case of Whiplash-Associated Disorder: Comparison of Imaging Tools for Diagnosis

Shan-Wen Lui¹, Kar-Wai Lui^2,3, and Shin-Tsu Chang^4,5*

¹School of Medicine, National Defense Medical Center, Taipei, Taiwan
²Department of Medical Imaging and Intervention, Chang Gung Memorial Hospital, Linkou, Taoyuan, Taiwan
³Department of Medical Imaging and Radiological Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan
⁴Department of Physical Medicine and Rehabilitation, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan
⁵Department of Physical Medicine and Rehabilitation, Tri-Service General Hospital, Taipei, School of Medicine, National Defense Medical Center, Taiwan

*Corresponding authors: Shin-Tsu Chang, Department of Physical Medicine and Rehabilitation, Kaohsiung Veterans General Hospital, Taichung and Department of Physical Medicine and Rehabilitation, Tri-Service General Hospital, School of Medicine, National Defense Medical Center, No. 161, Section 6, Minquan East Road, Neihu District, Taipei 11490, Taiwan E-mail:

Received: 10 June 2024 | Accepted: 15 August 2024 | Published: 16 August 2024

How to cite this article: Shan-Wen L, Kar-Wai L, Shin-Tsu C. Numbness of the Left Leg Caused by Perfusional Deficit in Right Parietal Lobe in a Case of Whiplash-Associated Disorder: Comparison of Imaging Tools for Diagnosis. J Biomed Res Environ Sci. 2024 Aug 16; 5(8): 983-988. doi: 10.37871/jbres1951, Article ID: jbres1757

Keywords

Whiplash-associated disorder
Numbness
Parieto-occipital hypoperfusion
Scintigraphy rehabilitation
Nociceptive-vascular hypothesis

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Abstract

Background: Since Whiplash-Associated Disorder (WAD) causes severe pain and even disability among patients, early diagnosis and therapy are essential to reduce personal and social costs. Traditionally, the diagnosis of WAD is mainly conducted through the examination of clinical symptoms and anatomical imaging with Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) but not Single-Photon Emission Computed Tomography (SPECT).

Case description: A 24-year-old woman reported having mild headaches and progressive left leg numbness six months after experiencing a whiplash injury during a rear-end motor vehicle crash. MRI, CT, and electromyographic examination of her left leg were all negative, but SPECT of her brain showed decreased activity in the right parieto-occipital lobes.

Conclusion: Our case highlights (1) the clinical significance of hypoperfusion in the parietal lobe inducing leg numbness instead of nerve dysfunction or nerve-to-muscle signal transmission, (2) the evolving usefulness of functional imaging patterns of SPECT, and (3) the concordance between clinical WAD symptoms and the functional imaging findings. We suggest that patients with WAD need study of nuclear scintigraphy of the brain for a more precise diagnosis.

Introduction

Whiplash-Associated Disorder (WAD) is commonly found among motorists who experience a motor vehicle crash. Recent publications show that approximately 30% of patients with WAD remain moderately to severely disabled [1,2], and up to 50% of patients never completely recuperate [3]. Because of the lack of specialized electrophysiological studies to diagnose WAD, patients with less or none grumble of pain or paresthesia or any radiologic substantiation of injury might be overlooked, resulting in substantial personal and social costs, including disability, work failure, and medical expenses [4].

The diagnosis of WAD mainly relies on clinical symptoms including headache, visual disturbances, neck pain or stiffness, memory impairment, concentration problems, arm pain or paresthesia or both, and psychological distress, as well as radiographic imaging studies to detect anatomical abnormalities [5]. Although Single-Photon Emission Computed Tomography (SPECT) is not routinely used to diagnose WAD, recent SPECT studies have revealed brain hypoperfusion in patients with WAD [6,7]. The use of SPECT to link brain hypoperfusion to the clinical symptoms of a patient with a functional neurogenic disorder has been reported [8].

We report a patient with WAD for whom we used SPECT imaging of the brain to make the diagnosis, which brain hypoperfusion was compatible with the clinical symptoms.

Case description

A 24-year-old female motorcyclist experienced a rear-end motorcycle-car crash four years previously. The motorcycle compressed her left ankle, causing severe lower leg pain and difficult walking. Mild neck pain and bilateral blurred visions also bothered her.

After six months of conservative treatment plus ankle injection, her left ankle pain and disability still persisted. Although her neck pain and blurred visions regressed, she developed new symptoms of headache and progressive left leg numbness. She was unable to stand, so she sought help from our hospital clinic. She could fluently and logically communicate with her physicians. MRI, CT, and electromyographic images of the spine and legs were negative for nerve dysfunction and abnormal nerve-to-muscle signal transmission as the possible causes of leg numbness. Injection therapy with platelet-rich plasma in her left ankle was given twice, and her ankle pain was relieved. The patient was discharged, and follow-up rehabilitation was prescribed. Nonetheless, the patient returned six months later, still reporting of left leg numbness. We examined the 99 mTc-Ethylene-Diylbis-L-Cysteine Diethyl Ester (ECD) SPECT images of her brain, which showed normal in the bilateral thalami, but obvious decreased perfusion in the right parietal (superior region) and right occipital lobes (Figure 1). As timeline shown in figure 2, the examination with CT and X-ray of multiple sites showed no destructive damage.

Discussion

In this case as shown on SPECT, we found the association not only between the patient’s bilateral blurred visions and occipital lobe hypoperfusion, but also hypoperfusion in the right parietal lobe and left leg numbness.

The patient reported numbness in the left leg. EMG findings were negative for nerve lesions, muscle dysfunction, and problems with nerve-to-muscle signal transmission, which conclusively excluded dysfunction of the left sciatic nerve. Sterling M, et al. [9] had shown that when patients who have had persisted moderate to severe warning signs within 6 months of WAD that some brain changes in mechanisms regarding central pain processing could possibly cause hypersensitivity symptoms. Although our patient had similarly moderate symptoms and injury to the central nervous system, she developed hyposensitivity in her leg. Due to hypoperfusion in the right parietal region on SPECT, psychological factors of disabilities were definitively excluded. Based on the above findings and those of previous studies [7,9], we conclude that the decreased blood flow in the parietal region caused by WAD affected the neurogenic pathway, which resulted in constant numbness of the left leg. A comparison between the patients reported by Sterling M, et al. [9] and our patient was shown in table 1.

Table 1: Summary of the patient’s clinical characteristics and a published study of WAD.
	Severity	Injured area involved 6 months post-injury	Symptom	Precise anatomical structure	Psychological distress
Our case	Moderate	Central nervous system	Hyposensitivity to pressure, pain and touch	SPECT image revealed hypoperfusion in the right parieto-occipital region	Definitively excluded
Sterling, et al. [9]	Moderate to severe	Central pain processing mechanisms	Hypersensitivity to pressure, pain, and temperature	No images presented	Unable to exclude
WAD: Whiplash-Associated Disorders; SPECT: Single-Photon Emission Computed Tomography.

Discomforts from patient with WAD are often ignored, possibly due to the difficulty in detecting abnormalities with CT/MRI and the fact that neuropsychological disturbances following whiplash are typically borderline [10]. These disturbances often present as non-specific symptoms, for instance, concentration and memory disturbances, which are common in other central disorders [11]. Although MRI offers brilliant soft tissue contrast and shuns ionizing radiation exposure, and CT provides detailed images of bone or hard structures, both modalities are limited in detecting functional changes in the brain, which reduces their utility in this aspect. Poor correlation between MRI and clinical manifestation of WAD has been reported by Karlsborg M, et al. [12], who concluded the prognosis of WAD is also not always associated with post-injury MRI [13]. In contrast, using SPECT can earlier detect cerebral blood flow abnormalities, allowing for timely interventions such as intravenous laser therapy to enhance the oxygen-carrying capacity and flexibility of red blood cells [14,15].

As a neuroimaging tool, SPECT allows for a better evaluation of brain functional status than other imaging tools. SPECT demonstrates the pathophysiological changes of neurological disorders that are so-called psychodynamic lesions [8] that correlate with clinical symptoms for making an accurate diagnosis, as with our patient. In the same way, in patients with dementia with Lewy bodies, significant decreased perfusion has been found through ECD-SPECT in frontal, parietal, temporal, and thalamus regions compared to the control group [16]. ECD-SPECT can be a helpful tool to help us understand the underlying mechanisms of WAD by providing functional insights into physiological processes and biological pathways. For lesions with cerebral blood flow alterations, SPECT can play a role in monitoring the brain plasticity. WAD emerges to be of mild to moderate injury intensity, and commonly occurs in the occipital lobe amid other brain areas [17]. Imaging with SPECT is essential in detecting acute lesions of a WAD [18], but might also play a role in the logistic ratiocination of unrelieved pathology.

Regional perfusion alterations in the brains of patients with WAD have been reported [7,19]. In a comprehensive review of WAD [7], the production of hypoperfusion in the parieto-occipital region was attributed to the nociceptive-vascular hypothesis. Vasoconstriction of brain vessels occurs with increased vasopeptide production triggered by nociceptive afferent nerves origininated from the upper cervical spine, which is under chronic stress and pain. These publications and concepts enhanced our understanding that in our patient’s case, hypoperfusion in the parieto-occipital lobe correlated with WAD.

Brain SPECT-CT is an imaging technique by using hybrid method in scintigraphic rehabilitation that merges SPECT and CT imaging to deliver detailed significance regarding the combination of the function and structure of the brain [20-33]. It is a great clinical tool to detect cerebral blood flow impairment and differentiate an ischemic event after stroke onset [34,35].

Finally, there are still some shortcomings in the diagnosis of WAD, and the connection between symptoms and mechanisms remains unclear, necessitating further research on neuroimaging techniques in WAD. For instance, the hybrid images of SPECT and MRI might help diagnose soft tissue injuries in patients with WAD, which has not yet been studied. Additionally, functional MRI, which can detect blood oxygen levels and produce images, aids in indirectly measuring neural activity and mapping the affected brain regions [36]. Its role in diagnosing WAD has not been fully recognized. With these diagnostic tools, combined with brain SPECT-CT, we might be able to further validate the nociceptive-vascular hypothesis and elucidate the underlying mechanisms of the disease. A comparison of the characteristics for MRI,CT, and SPECT-CT was made in table 2.

Table 2: A comparison of the characteristics for MRI, CT, and SPECT-CT in brain pathology.
	MRI	CT	SPECT-CT
Principle	Using magnetic fields and radiofrequency pulses to produce images	Using computerized X-ray imaging from multiple angles to create images	Hybrid images with combination of SPECT and CT
Anatomical accuracy	Excellent	Excellent	Excellent
Soft tissue contrast	High	Low	Moderate
Radiation exposure	None	Moderate	Moderate
Functioning imaging	Absent	Absent	Simultaneous inspection of brain structure and corresponding location in the SPECT, but not real time
Cost	Most expensive	Less expensive than MRI	Less expensive than MRI
Manpower consumption	Low	Low	Moderate

In conclusion, our report provides insight into the evolving functional imaging patterns that can be seen with SPECT in contrast to anatomical images like those produced by CT and MRI. Additionally, we have shown that hypoperfusion in the parietal lobe can induce leg numbness instead of nerve dysfunction or nerve-to-muscle signal transmission, and most importantly, we have shown concordance between clinical WAD symptoms and the SPECT-CT functional imaging findings. We suggest that those patients with WAD and clinical symptoms discordant to anatomical image findings should undergo nuclear scintigraphy of the brain for a more precise diagnosis.