Table 2.

Description of the characteristics of the patients

Author and year (title)	Patient	COVID-19 symptom onset and method of diagnosis	Neuropathic pain/condition (presentation)	Investigations done	Interventions (drugs)	Results	Conclusions
Catherine Young Han et al. [11] Brachial plexopathy as a complication of COVID-19	Age: 52 years Gender: male Past history: hypertension and diabetes mellitus Place: USA	4 days before onset of neuropathic symptoms RT-PCR	Severe upper extremity weakness and neuropathic pain in the left hand and forearm	MRI, NCV, EMG	Gabapentin, oxycodone, acetaminophen, physical therapy. Wrist sprint	Neuropathic pain resolved and improvement in other symptoms also	Covid-19 induced hypercoagulability can cause microthrombotic complications in multiple organ systems. In this patient, microthrombi occluded vasa nervorum supplying the brachial plexus causing brachial plexopathy. Early investigations and therapy should be considered
Feyzullah Aksan et al. [12] A COVID-19 patient with intense burning pain	Age: 45 years Gender: female Past history: hypertension, obesity, COPD, asthma Place: USA	Six days before onset of neuropathic symptoms RT-PCR	Neck and back pain ranging from C1 to L5, encompassing the paraspinal and trapezius muscle areas	None	Acetaminophen, NSAID, oxycodone, tramadol, gabapentin	Gabapentin relieved pain and hypersensitivity to touch also improved	Infection caused neuropathic pain in this patient and gabapentin was effective
Andrew R. Shors [14] Herpes zoster and severe acute herpetic neuralgia as a complication of COVID-19 infection	Age: 49 years Gender: female Past history: nothing Place: USA	One week after the onset of neurological symptoms, COVID test was done RT-PCR	Itchy rash on trunk, several vesicles and papules on face. Skin burning, allodynia with sinus and tooth pain, severe neuralgia	None	Valacyclovir 1 g 3 times daily, gabapentin, topical lidocaine	Partial control of symptoms	In this patient, viral infection causes inflammation at the dorsal root ganglion and led to strong herpes response
Xueqin Cao et al. [13] Herpes zoster and postherpetic neuralgia in an elderly patient with critical COVID-19: a case report	Age: 70 years Gender: female Past history: diabetes, myasthenia gravis (on medications) Place: China	One and half month before the onset of neurological symptoms of pain. Diagnosis of COVID-19 is made RT-PCR	small red papules on the right side of waist with sharp pain (9 on 11-PNRS)	None	IV acyclovir and prednisolone (20 mg orally), infrared therapy, pregabalin, ibuprofen	Gradual relief in symptoms (took medicines for pain management for one and half month)	COVID-19 infection decreases T lymphocytes and myasthenia gravis also caused dysregulation of regulatory T cells and elevated IL-6. This caused immunosuppressive illness herpes zoster in this patient. Early anti-viral therapy helped the patient
Javier Molina-Gil MD et al. [15] Trigeminal neuralgia as the sole neurological manifestation of COVID-19: a case report	Age: 65 years Gender: male Past history: nothing Place: Spain	Three days after neurological pain started RT PCR, D-dimer	Sudden excruciating pain in the right V1 region triggered by light touch	Cranial Magnetic Resonance with MR angiography, blood count, infectious serologies, RFT, LFT, thyroid profile	Diazepam 10 mg and pregabalin 300 mg	Relief in pain	COVID-19 virus invades the CNS retrogradely and bind to angiotensin and convert it to enzyme type 2, presenting trigeminal Neuralgia
Mathew McWilliam et al. [16] Neuropathic pain post-COVID-19: a case report	Age: 61 years Gender: male Past history: none Place: UK	One week before the onset of neuropathic pain RT PCR	A brief sensation of burning throughout the body, followed by paraesthesia and scorching pain in both feet and hands	ESR, IgG, CBC, liver function, renal, folic acid, B12, glycated haemoglobin-bin(HbA1C), calcium,,cholesterol, vitamin D, thyroid function tests MRI brain, whole spine and brachial plexus, NCVs, CSF analysis	Amitriptyline, 10 mg; nortriptyline, 10 mg; ineffective Pregabalin 25 mg, minimal benefit Pregabalin 75 mg, continued	Pain score reduced to 2/20 from 7/10 score	This patient is suspected to have a post-infectious autoimmune small fibre polyneuropathy which is a sensory neuropathy that predominantly affects small fibres and their functions
Timo Siepmann et al. [17] Neuralgic amyotrophy following infection with SARS-CoV-2	Age: 52 years Gender: male Past history: none Place: Germany	One week before the onset of pain RT-PCR	Severe constant pain in the right shoulder intensified on shoulder extension, shifted distally with paraesthesia in fingers, followed by progressive weakness of the hand	NCV, EMG of the hand muscles and nerves, MRI and nerve ultrasound of the median nerve. CSF analysis	Oral prednisolone (1 mg/kg weight)	Little pain relief with no improvement in muscle power	This patient of mono-neuropathic brachial neuritis on the dominant side after SARS-CoV-2 infection suggests a probable link between neuralgic amyotrophy and COVID-19
Mario Cacciavillani et al. [18] Pure sensory neuralgic amyotrophy in COVID-19 infection	Age: 52 years Gender: male Past history: none Place: Italy	15 days before the onset of pain RT-PCR	Excruciating pain in the left upper limb followed by hypoesthesia and dysesthesia	NCV, EMG of left upper limb muscles and ultrasound of the left upper limb nerves	Acetaminophen	Pain resolved completely, hypoesthesia and dysesthesia was present	Neuralgic amyotrophy might manifest itself as pure sensory involvement. Infections like covid-19 that occur before or after an immune-mediated pathophysiologic process are thought to be probable triggers

RT-PCR Reverse Transcription-Polymerase Chain Reaction, MRI Magnetic resonance imaging, NCV nerve conduction velocity, EMG Electromyography, COPD chronic obstructive pulmonary disease, NSAID non-steroidal anti-inflammatory drug, 11-PNRS 11 point numeric rating scale, MRI magnetic resonance imaging, CMV cytomegalovirus, EBV Epstein Barr virus, HAV hepatitis A virus, AHBc anti-hepatitis B virus, HIV human immunodeficiency virus, IgM immune globulin M, CSF Cerebrospinal fluid, RFT Renal Function Test, LFT Liver Function Test, ESR Erythrocyte Sedimentation Rate